Exo Cruiser

Aerospace Goodies

2012-01-19T09:50:00.001Z

I put here a link to the TU Delft (Netherlands) website:

View Larger Map

"Aerostudents website is made primarily for the students of the bachelor phase of the faculty of Aerospace Engineering at the TU Delft. It contains a lot of summaries which help students with their studies. If you're new here, take a look at the About This Website section for more information about this website."

http://www.aerostudents.com/info/home.php

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How to Build a Car PC

2011-12-19T03:38:00.000Z

Three part video about how to build a car PC.

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What flaps can do?

2011-11-26T11:05:00.010Z

Some videos about what flaps can do and how much the zero lift angle of attack moves when using them.

BTW: These full span flaps look very much like those patented 1952 by Youngmann. See more in the following link:

http://dodlithr.blogspot.com/2009/01/rt-youngman-full-span-flaps.html

And here is a diagram about what flaps can usually do for the lift coefficient. Using for example type (7) configuration the wing is generating 2.4 time more lift than the wing alone and 1.4 times more than the plain flap (2) alone. The reduction of the wing size (and drag) is proportional to that although the less clean wing adds some drag but we have to remember that most designs can not benefit so much about the cleanness of the wing. /1/

From Loftin, NASA Sp 468, 1985

Typical values of airfoil maximum lift coefficient for various types of high-lift devices: (1) airfoil only, (2) plain flap, (3) split flap, (4) leading-edge slat, (5) single-slotted flap, (6) double-slotted flap, (7) double-slotted flap in combination with a leading-edge slat, (8) addition of boundary-layer suction at the top of the airfoil.

REFERENCES

/1/ http://www.dept.aoe.vt.edu/~jschetz/fluidnature/

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Form, Lift, Drag and Propulsion

2011-11-20T16:47:00.001Z

Some videos from the University of Iowa: /1/

"In the fifth video of the series, emphasis is laid upon the role of boundary-layer separation in modifying the flow pattern and producing longitudinal and lateral components of force on a moving body. Various conditions of separation and methods of separation control are first illustrated. Attention is then given to the distribution of pressure around typical body profiles and its relation to the resulting drag. The concept of circulation introduced in the second film is developed to explain the forces on rotating bodies and the forced vibration of cylin dri cal bodies. Structural failure of unstable sections is demonstrated."

"Introduction to the timeless educational series by brilliant German aeronautical engineer Dr. Alexander Lippisch, explaining the phenomena and physics of of flight in an understandable and engaging manner. Produced in 1955 by the University of Iowa."

REFERENCES

/1/ http://www.youtube.com/user/universityofiowa#g/u

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What plane?

2011-11-18T19:09:00.003Z

This picture was in a magazine taken before 1927. The question was what is the plane with that strange over the wing motor installation?

Since it is a monoplane before 1927 and the guy (pilot) smoking on the right looks very much like Anthony Fokker it must be some prototype of the Fokker F VII. Here are some additional pictures and videos of the F VII model.

On the left Anthony Fokker sitting in a cockpit frame

Last flight of a Fokker F.VIIa

Fokker F.VII was also the first airplane to fly over the north pole.

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Ray Hopper and Dave Grant, Spruce Goose Designers Interview

2011-11-17T20:40:00.003Z

Ray Hopper and Dave Grant were designers and engineers of the Howard Hughes flying boat Spruce Goose. Here is an interview of them in 6 parts.

Some pictures about the Howard Hughes HK-1 (H-4) Hercules ("Spruce Goose").

REFERENCES

/1/ http://en.wikipedia.org/wiki/Hughes_H-4_Hercules

/2/ http://news.google.com/newspapers?nid=2206&dat=19791105&id=lNYzAAAAIBAJ&sjid=dOsFAAAAIBAJ&pg=3058,1725498

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A Wooden Wing Failure in 1931 (TWA Flight 599)

2011-11-16T16:41:00.006Z

Fokker F.10A Trimotor

Early wooden wings had some mishaps which promoted the use of the (at that time) new full aluminium wing. Here is the story of the Fokker F.10 (TWA Flight 599) as told in the Popular Mechanics, Dec., 1971. Not only did the wooden wings have problems, also two Lockheed Electras crashed in 1959 and 1960 due to flutter in the now fully aluminium wing.

These planes were built in America by the Fokker Aircraft Corporation and not in Europe as one might believe when Fokker name is mentioned. /2/

"The weather was inauspicious. So much so that Anthony Fokker would later angrily argue that the flight should never have gone ahead." /4/

March 31, 1931 - Bazzar, Kansas , Fooker 10A Trimotor , Trans Continental and Western Air flight number 599.

"Heathman, who was 13 years old at the time he discovered the plane crash with his father on March 31, 1931, was the last living witness to the plane crash." /3/

Video about Fokker F.10

"Fokker Trimotors were manufactured out of wood laminate; in this instance, moisture had leaked into the interior of one wing over a period of time and had weakened the glue bonding the structural members (called struts or spars) that prevented the wing from fluttering in flight. One spar finally failed; the wing developed uncontrolled flutter and separated from the aircraft." /1/

Anthony Fokker (center) in the F.10A (Image: Dutch Aviation)

So to say that sensitive wooden structures should be protected against moisture also inside and tested agains flutter (and go around bad weather).

REFERENCES

/1/ http://en.wikipedia.org/wiki/TWA_Flight_599

/2/ Popular Mechanics, Dec. 1971

/3/ http://en.wikipedia.org/wiki/James_Heathman

/4/ http://www.irishlegends.com/pages/reflections/reflections49.html

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Composite Construction Techniques

2011-11-07T02:06:00.006Z

Some YouTube videos about composite airplane manufacturing:

Aero-TV: Composite Construction -- The Cirrus... by AeroTVNetwork

Aero-TV: Under The Skin -- How Cirrus Builds... by AeroTVNetwork

Some one time methods:

Some mold making ideas:

And some videos about using those molds:

Here are the vacuum bagging steps again. In the video they vacuum bagged it twice; once before the honeycomp was laid and second time with all layers.

0 - Mold (see separate videos for mold making)
1 - 4 layers carbon
1.1 - 0 layer
1.2 - 45 layer
1.3 - 45 layer
1.4 - 0 layer
2 - peel-ply
3 - breather/bleeder
4 - bagging film + vacuum
5 - honeycomp
6 - 3 layers carbon
6.1 - 0 layer
6.2 - 45 layer
6.3 - 0 layer
7 - peel-ply
8 - breather/bleeder
9 - bagging film + vacuum

("Molds should have at least 3 times more layers than parts to be pulled out of them.")

The following video from the same source is also very informative (in 8 parts).

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Horten H IX (or Ho 229 or Gotha Go 229) Construction Details and Story

2011-10-30T18:26:00.050Z

The Horten Ho 229 V.3 is Currently been Restored and Preserved

Horten Ho 229 (IX) V.3, June 2011

"Early in June 2011, staff of the Paul E. Garber Preservation, Restoration and Storage Facility slowly and carefully moved the center section of the Horten H IX V.3 all-wing jet fighter from storage into the restoration and preservation shop." /4/

General

"The H IX was a single seat fighter bomber of 16 m span with twin jet engines, being a further development of the H V and H VII designs. The following figure is a general arrangement drawing made from a wooden model found at Gottingen 1945 (Gotha, Friedrichroda), where the first two of the type were built." /6/

General arrangement drawing made from a wooden model found at Gottingen

"Four (actually 6) aircraft of the H IX type were started, designated V.1 to V.4 (V.6). V.1 was the prototype, designed as a single seater with twin B.M.W. 003 jets, which were not ready when the airframe was finished. It was accordingly completed as a glider (not reproducible) and extensively test flown." /6/

("V" - German word "Versuch" literally test or experiment)

V-1 was completed as a glider (no turbines)

"D.V.L. (Deutsche Versuchsanstalt für Luftfahrt) instrumented it for special directional damping tests to determine its suitability as a gun platform."

V.2 (later crashed)

"V.2 was completed (also at Gottingen) with two Jumo 004 units and did 2-hours flying before crashing during a single engine landing. The pilot (Ziller) apparently landed short after misjudging his approach. (Ziller was killed)"

V.3 was never flown (photo by Allied troops that captured the factory at Friedrichroda)

"V.3 was being built by Gotha at Friedrichsrodal as a prototype of the series production version (and later shipped to USA)."

V.4 (The V4 had received the engines and the works had begun to create the wood structure.)

"V.4 (V5 and V.6) did not get beyond the project stage. V.4 was to be a two-seater night fighter with an extended nose to house the extra man." /6/

V.5 (An American soldier standing by the side of the V5 prototype)

"In shape, the H IX was a pure wing with increased chord at the center to give sufficient thickness to house the pilot and the jet units, which were placed close together on either side." /6/

Gothaer Waggonfabrik

"Gothaer Waggonfabrik (Gotha, GWF) was a German manufacturer of rolling stock established in the late nineteenth century at Gotha. During the two world wars, the company expanded into aircraft building." /9/

Gotha logo

"February 24th and July 20th, 1944 the factory was 80% destrayed in air-raids. Nevertheless the production of Horten prototypes moved to Gotha, Friedrichroda in 1945. After the war 1949 the company was state owned using the name VEB Waggonbau Gotha." /10, 11, 12/

The Gothaer Waggonfabrik, AG, Gotha, Germany was bombed February 24th and July 20th, 1944. /11/

Northrop-built reproduction /1/

Video about Northrop's Ho 229 reproduction techniques

"After the war, Reimar Horten said he mixed charcoal dust in with the wood glue to absorb electromagnetic waves (radar), which he believed could shield the aircraft from detection by British early warning ground-based radar known as Chain Home. A jet-powered flying wing design such as the Horten Ho 229 will have a smaller radar cross-section than conventional contemporary twin-engine aircraft. This is because, with wings blended into the fuselage, there would be no large propeller disks or vertical and horizontal tail surfaces to provide a typical identifiable radar signature." /1/

Reimar und Walter Horten

"Reimar, Walter and Wolfram Horten were three brothers who were born and raised in the Germany of the early 20th century. Wolfram was killed (shot down) early in the World War II (20. May 1940) over Dünkirchen in a Heinkel He 111." /2/

The National Air and Space Museum (NASM) of the Smithsonian Institution holds the largest collection of historic aircraft and spacecraft in the world

"Engineers of the Northrop-Grumman Corporation had long been interested in the Ho 229, and several of them visited the Smithsonian Museum's facility in Silver Hill, Maryland in the early 1980s to study the V3 airframe. A team of engineers from Northrop-Grumman ran electromagnetic tests on the V3's multilayer wooden center-section nose cones. The cones are three quarters of an inch (19 mm) thick and made up of thin sheets of veneer. The team concluded that there was indeed some form of conducting element in the glue, as the radar signal slowed down considerably as it passed through the cone." /1/

"In early 2008, Northrop-Grumman paired up television documentary producer Michael Jorgensen, and the National Geographic Channel to produce a documentary to determine whether the Ho 229 was, in fact, the world's first true "stealth" fighter-bomber. Northrop-Grumman built a full-size reproduction of the V3, incorporating a replica glue mixture (see below for details) in the nose section. After an expenditure of about US$ 250,000 and 2,500 man-hours, Northrop's Ho 229 reproduction was tested at the company's classified radar cross-section (RCS) test range at Tejon, California, where it was placed on a 15-meter (50 ft) articulating pole and exposed to electromagnetic energy sources from various angles, using the same three frequencies in the 20–50 MHz range used by the Chain Home in the mid-1940s." /1/

Tejon Ranch RCS Facility

"The Northrop facility goes by the name of Tejon Ranch (pronounced tay-on) or Tejon Ranch RCS Facility, and is sometimes referred to as the "Tehachapi Ranch." It is located in the foothills of the Tehachapi mountains, at the mouth of Little Oak Canyon, about 25 miles northwest of Lancaster, California, and 18 miles due west of the town of Rosamond. It is not under restricted airspace. Although publicly said to be a cattle ranch, no livestock are visible anywhere on the property. The long, wide surfaces said to be visible in aerial photos are not runways, though there are said to be white-painted diamond-shaped features on these surfaces. A white pylon is visible in the center of one diamond shape, and a pylon "rack" and antenna array are located near the main buildings." /5/

Wings of V.3

"RCS testing showed that a hypothetical Ho 229 approaching the English coast from France flying at 885 km/h (550 mph) at 15–30 metres (50–100 ft) above the water would have been visible at a distance of 80% that of a Bf 109. This implies an RCS of only 40% that of a Bf 109, from the front at the Chain Home frequencies. The most visible parts of the aircraft were the jet inlets and the cockpit, but caused no return through smaller dimensions than the CH wavelength. However, the speed of the aircraft, combined with the 20% advantage created by its stealth characteristics, would have made it a serious threat, able to begin an attack before defenses could be brought into play and continuing at a speed too fast for conventional fighter aircraft to nullify." /1/

The Horten Ho 229 replica in the San Diego Air and Space Museum

"With testing complete, the reproduction was donated by Northrop-Grumman to the San Diego Air and Space Museum. The television documentary, Hitler's Stealth Fighter (2009), produced by Myth Merchant Films featured the Northrop-Grumman full-scale Ho 229 model as well as CGI reconstructions depicting a fictional wartime scenario where Ho 229s were operational in both offensive and defensive roles." /1/

The Ho IX Twin Jet /3/

Hermann Göring was a veteran of World War I and an ace fighter pilot

"In a speech before representatives of the aircraft industry, Reichsmarshall Goering had announced that no new contracts would be given, unless the proposed aircraft could carry 1000 kg bombs, fly 1000 km /h, and have a penetration depth of 1000 km; penetration depth being defined as the total range."

MK-101 30mm aircraft cannon

"The Fighter Division requested that the aircraft also be fitted with 30 mm machine guns, something that would lessen the machine's efficiency as a bomber."

"We (Horten brothers) started drawing and calculating without a contract. Our plan was to build two full size prototypes. The initial penetration depth would only be 800 km, since the fuel proof glue necessary for the full wet wing, was not yet available. On the other hand, the smaller fuel load allowed a doubling of the bomb load, so we went ahead and submitted our proposal."

Horten H IX (Ho 229 or Gotha Go 229) V.3 cutaway

"A contract was awarded with the demand that the first flight be made in six months! Since the jet engine was not yet ready, the first machine would be a glider. The previously deactivated Air Force Command IX was reactivated, and ordered to proceed with the project. Fortunately, the preliminary work that we did without a contract, put us sufficiently ahead, so the six month deadline locked feasible."

"There were several reasons for choosing wood as the building material. Duraluminum required more energy to produce; over 3000 KWH, versus less than 3 KWH for wood per ton. The required labor for aluminum production was also much higher; 5000 hr/ton against 200 hr/ton for wood. In addition, aural was difficult to find, and skilled sheet metal workers in short supply. Unskilled workers could easier be trained to work with wood."

A triangular piece of spruce, sandwiched between two plywood sheets

"Typically, a nose rib was built from a triangular piece of spruce, sandwiched between two plywood sheets, all scrap wood. Production time: 10 minutes. After the glue dried, the rib was simply roused out along a master template in less that 5 minutes. The rest of the wing was built in a similar crude fashion, to pave the way for mass production by unskilled workers."

Wings

"The main box spar contained all cables and control rods, to free the remaining space in the wing for fuel. That, we planned to pump right into the wing itself, without tanks or bladders. To do this, we needed the fuel-proof glue, that could be used to coat the inside surfaces as well. The glue allowed additional gluing to dissolve and adhere to already coated surfaces, which greatly simplified construction."

Charcoal

"The skin was very thick: 17 mm, all plywood; three times the necessary strength. On the production aircraft, this would be replaced by two 1.5 mm plywood sheets, with a 12 mm layer of sawdust, charcoal and glue mix, sandwiched in between."

17 mm sandwich with 12 mm layer of radar absorbing material inside

"The charcoal in this much lighter skin would diffuse radar beams, and make the aircraft "invisible" on radar."

Sawdust

"Finally, should a 20 mm shell explode inside the wing, a relatively harmless hole would result, whereas a metal wing would balloon out and lose its lift."

"The H IX wing was designed with 3 geometric and 1.5 aerodynamic twist, to give it the desired bell shaped lift distribution with all controls neutral."

Different aileron (elevon) types

"The Frise-nose on the elevons had proven to be unsatisfactory, so we decided to use blunt nose elevons instead. The sharply enlarged wing root chord served mainly to eliminate the middle-effect. The maximum thickness line (T-4 line) therefore made a sharp bend in the middle, which resulted in the characteristic pointed tail. As this would affect stability, a test aircraft with large aspect ratio, that had the control surface far outside the test area, was needed. The H Vl would serve this purpose, while other preliminary tests were made with a H II and a H III."

Heinkel He 45

"The H IX V-1 took off right on schedule on March 1, 1944 in Gottingen. The small He 45 towplane barely got off the ground, so test pilot Scheidhauer released, and landed straight ahead, after only a short hop. Five days later, he was off again on a snow covered runway behind an infinitely more powerful He 111. He released at 12000 feet, made an uneventful glide back to the airport, then faced problems during landing when the drag chute did not function. As the end of the runway approached, he retracted the nose wheel, and skidded to a stop with only minor damage."

Heinkel He 111

"The second aircraft, scheduled to fly three months later, was awaiting its engines, promised in March. Several weeks passed, and then... Disaster!"

The engine diameter was 20 cm too large

"The engines arrived with an accessory section added to the case, making the cross section oval, and the diameter 20 cm greater! No one had bothered to inform us! Now, just six weeks before the first flight, we were faced with the problem of fitting an 80 cm engine into an aircraft with a 60 cm hole in the spar! It meant that the wing would have to be made thicker." (Junkers Jumo 004 had larger diameter than the BMW 003 turbine)

"To maintain the aerodynamic qualities of our design, we would have to increase the span from 16 to 21.3 meters, and the wing area from 42 m2 to 75 m2. Such an aircraft would never reach the targeted performance, even with higher engine thrust. We choose instead to do the best we could with patchwork modifications. The wings remained the same. Another root rib was added 40 cm outside the original, making the center section 0.8 m wider. The new airfoil was 13% thicker than before, and the bend in the T-4 line became much larger. The thicker center section lowered the critical Mach number to 0.75, or a maximum speed of 920 km/h."

Heinkel He 177 "Greif"

"The ratio of movement between the control column and the elevons could be reduced to by the pilot for high speed flight. A small high speed drag rudder was supplemented by a larger one that deployed after the smaller was fully extended. Many parts were scrounged from other aircraft left at the test facility in Gottingen. The nose wheel, for instance, came from the tail wheel of a He 177 heavy bomber. We were even able to use the strut and retract cylinder!"

"The men of Air Force Command IX did their utmost to complete the aircraft before the end of 1944, sometimes working more than 90 hours per week."

Lt. Erwin Ziller

"I remember that Lt. Erwin Ziller made the first flight about December 18th, 1944, but his log book indicates that the first flight occurred on February 2nd., 1945. I am quite sure the first flight of the H IX was also his first in a jet. Our leaders had little concern for such risks."

"Satisfied with the initial flight, the Air ministry ordered 40 aircraft to be built by the Goetha Waggonfabrik under the designation 8 -229."

Ziller in V.2

"It appears that the H IX V-2 had flown three or four times before tragedy struck on February 18th. The many versions of the story have a few things in common. The weather was overcast, the ground soft and muddy. The visibility marginal for a test flight, as Lt. Ziller took off, retracted the gear and disappeared. We received a report that one engine had failed, and that the H IX was returning to Oranienburg. Due to the low ceiling, a shallow approach to the airport was initiated. Since the hydraulic pump was on the dead engine, gear and flaps were extended by the emergency compressed air system. Once down, they could no. be retracted. To maintain his glide slope, Lt. Ziller added power. to overcome the extra drag, and found to his horror that he could" no longer maintain directional control; the fully developed drag rudder unable to overcome the asymmetrical thrust. Rather than lose control, he retarded the throttle to land short of the runway. The aircraft touched down in a field, slid into an embankment and flipped over, crushing its pilot."

The cockpit did not offer any protection for the pilot if it flipped over

"The Third US Army Corps reached the Goetha plant on April 14th 1945. Here they found the H IX V.3 intact and nearly completed, and also the V.4, V.5 and V.6 in various stages of completion."

Possible later picture of the V.1

"The Ninth US Armored Division found the H IX V.1 in good condition near Leipzig. Its fate is unknown."

V.3, 1945

"The H IX V.3 was later 1945 shipped to USA, and is now in the Smithsonian collection, awaiting restoration." /3/

V.3, 2011

"Early in June 2011 the center section was slowly and carefully moved from storage into the restoration and preservation shop." /4/

Aerodynamic Design

"The H IX started as a private venture and the Hortens were very anxious to avoid failure so they avoided aerodynamic experiments wherever possible. A lower sweepback was used than on the H V and H VII and laminar flow wing sections were avoided as a potential source of trouble. Wing section at the junction with the center sections was 14% thick with maximum thickness at 30% and 1.8% zero Cmo camber line (Cmo, pitching moment coefficient). At the centerline thickness was increased locally to 16% to house the crew. The tip section was symmetrical and 8% thick. Horten also believed that since the compressibility cosine correction to drag was based on the sweepback of the maximum thickness line, the ordinary section would show little disadvantage." /6/

Large front landing gear carried 40% of the load, it retracted behind the pilot

"Wing twist was fixed by consideration of the critical Mach number of the underside of the tip section at top speed. This gave a maximum washout of 1.8°. Having fixed this, the CG was located to give trim at CL = 0.3 with elevons neutral. In deciding twist for high speed aircraft, CD values were considered in relation to local CL at operational top speed and altitude (10 km in the case of the H IX). Twist was arranged to give minimum overall drag consistent with trim requirements. The wing planform was designed to give a stall commencing at 0.3 to 0.4 of the semi-span." /6/

The center section (fuselage) was made of welded steel tube frame covered with plywood

Structure

"Wing structure comprised a main spar and one auxiliary spar of wooden construction with ply covering."

V.3 wing

"The center section ("fuselage") was built up from welded steel tube."

The welded steel tube center section of V.3

"Wing tips were all metal. The undercarriage was completely retractable and of tricycle type the front wheel folding backwards and the main wheels inwards."

V.2 landing gears

"The nose wheel was castering and centered with a roller cam. When resting on the ground, wing incidence was 7° and the nose wheel took about 40% of the total weight." /6/

Engine Installation

"The jet engines (BMW 003 or Junkers Jumo 004) were installed at -2° to the root chord and exhausted on the upper surface of the wing at 70% back from the nose."

"To protect the wings the surface was covered with metal plates aft of the jet pipe and cold air bled from the lower surface of the wing by a forward facing duct and introduced between the jet and the wing surface. The installation angle was such that in high speed flight the jest were parallel to the direction of flight." /6/

BMW 003 jet engine

"Specifications (BMW 003A-1)

Type: Non-afterburning turbojet

Length: 3,530 mm (139 in)

Diameter: 690 mm (27 in)

Dry weight: 562 kg (1,240 lb)

Compressor: 7-stage axial compressor

Combustors: Annular

Turbine: Single-stage

Fuel type: 87 Octane petrol

Maximum thrust: 800 kgf (7.8 kN; 1,760 lbf) at 9,500 rpm

Specific fuel consumption: 14.4 kg/(kN·h) (1.44 lb/(lbf·h))

Thrust-to-weight ratio: 13.9 N/kg (1.42)"

Hermann Östrich

"The BMW 003 began development as a project of the Brandenburgische Motorenwerke (The Brandenburg Motor Works, known as "Bramo ") under the direction of Hermann Östrich and assigned the RLM designation 109-003 (using the RLM's "109-" prefix, common to all jet and rocket engine projects). Bramo was also developing another turbojet, the 109-002. In 1939, BMW bought out Bramo, and in the acquisition, obtained both engine projects. The 109-002 had a very sophisticated contra-rotating compressor design intended to eliminate torque, but was abandoned in favour of the simpler engine, which in the end proved to have enough development problems of its own."

Junkers Jumo 004 jet engine

"Turbojet, Junkers Jumo 004 B

Junkers Flugzeug- und Motorenwerke AG, Dessau, Germany, 1944

The first large-scale production of turbojets began with the Jumo 004B at the end of 1943. The development of the 004 engine was directed by Anselm Franz in Dessau from 1939 onwards. Series-production of Jumo 004A engine, designed for test purposes, started in sommer 1942.

8-stage axial-flow compressor, single stage turbine, 6 combustion chambers

Static thrust: 8.9 kN

Number of revolutions: 8700 rpm

Fuel consumption 1273 kg/h

Specific consumption 143 kg/kNh

Air flow: 21.2 kg/s

Compression ratio: 3.1"

Dr. Ing. Anselm Franz

"Dr. Ing. Anselm Franz, director of the gas turbine engine development at Junkers in Germany from 1940 to 1945 came to the US with Operation "Paperclip" in 1946 and became vice president and assistant general director at AVCO Corp. Lycoming Division in Connecticut were he continued his management efforts developing gas turbine engines. Most of the Lycoming gas turbine engines were designed by Franz and his team of engineers."

"Dr. Anselm Franz was place in charge of developing a new gas turbine engine for helicopters in 1952. The result was the T53, a light, powerful design that became Lycoming's most popular engine. T53s later drove the Bell UH-1 Huey and AH-1 Cobra helicopters and Grumman OV-1 Mohawk reconnaissance aircraft." /15/

Control System

V.3 Controls

"Lateral and longitudinal control was by single stage elevon control flap with 25% Frise nose and compensating geared tap balance. (This system was also used on the Horten VII)."

V.3 cockpit

"The pilots control column was fitted with a variable hinge point gadget, and by shifting the whole stick up about 2” the mechanical advantage could be doubled on the elevons for high-speed flight." /6/

Drag rudders in V.2

"Directional control was by drag rudders. These were in two sections, slight movements of the rudder bar opening the small (outboard) section and giving sufficient control for high speed. At low speeds when courser control was necessary the large movement also opened the second spoiler, which started moving when the small one was fully open. By pressing both feet at once, both sets of spoilers could be operated simultaneously; this was stated to be a good method of steadying the aircraft on a target when aiming guns."

V.1 cockpit

"The Hortens stated that the spoilers caused no buffeting and claimed an operating force of 1 kg for full rudder, with very little variation in speed. The operating mechanism is illustrated in the following figure. A change was made from the original Horten VII parallel link system to improve the control force characteristics. With the new system, aerodynamic forces could be closely balanced by correct venting of the spoiler web, leading the main control load to be supplied by a spring. The cover plate of the spoilers was spring loaded to form an effective seal with the rudders closed; this device was used on most Horten spoiler and dive brake designs." /6/

V-3 Drag rudder

"On further models of the H IX it was proposed to fit the “trafficator” type rudder tried experimentally on the H VII." (Possible due to the "one engine out" crash of V.2?) /6/

V.3 Control System

"Landing flaps consisted of plain trailing edge flaps (in four sections) on the wings, with a 3% chord lower surface spoiler running right across the center section, which functioned as a glide path control. The outer pair of plain flaps lowered 27° and the inner pair 30° – 35° on the glider version V.1. On V.2 mechanical trouble prevented the inner pair operating and all flying was done with the outer pair only." /6/

Center section spoiler

"The center section spoiler could be used as a high speed brake and gave 1/3 g at 950 km/h. No dive recovery flap was considered necessary." /6/

Performance

"Proper performance tests were not done on V.2 before its crash and top speed figures were calculated values, checked by Messerschmitts. The following figures were remembered by Reimar Horten:" /6/

Dimensions /6/

All Up Weight, Incl. Ammunition and Armor 8,500 kg (18,700 lbs.)
All Up Weight, Excl. Ammunition and Armor 7,500 kg
Wing Area 52 sq.m (566 sq.ft.)
Wing Loading 33 lb./sq.ft.
Fuel (I2 Crude Oil) 2,000 kg (4,400 lbs.)
Performance at 7,500 kg (16,500 lbs.)
Takeoff Run 500 m
Takeoff Speed (10° Flap) 150 km/h (95 mph)
(Note: This corresponds to a CL of 1.30 which is the stated stalling CL of the aircraft.)
Top Speed (at Sea Level) 950 km/h (590 mph)
(CDo estimated to be 0.011)
Calculated ceiling was 16 km (52,000’).
Engines would not work above 12 km as the burners went out.
Rate of Climb at Sea Level 22 m/sec (4,300 ft/min)
(Note: This has been checked roughly by observation.)

"In tests against the Me 262 speeds of 650-700 km/h (400-430 mph) were obtained on about 2/3 throttle opening. This appears to be the only flight test figure available." /6/

"Messerschmitt sent performance calculators to the Horten works to check their estimates. The method suggested by D.V.L. for getting the sweepback correction to compressibility drag was to take an area of 0.3 x the root chord squared at the center section as having no correction applied, and then apply full cosine correction over the outer wing. Sweepback angle was defined as that of the quarter chord locus. Test data was available for CDv. for zero sweepback." /6/

"The Messerschmitt method was to base sweepback on the max t/c locus and to scale Mach number by the square root cos Ø." /6/

Stability and Control

"The H IX V.1 was flown by Walter Horten, Scheidhauer and Ziller. Scheidhauer did most of the flying (30 hours) at Oranienberg, Horten and Ziller flew for about 10 hours." /6/

Heinz Scheidhauer, pilot of Horten IX V.1 (Göttingen 1944)

"D.V.L. (Deutsche Versuchsanstalt für Luftfahrt) instrumented the aircraft for drag and directional stability measurements. No drag results were obtained because of trouble with the instrument installation – apparently an incidence measuring pole was fitted which could be lowered in flight and glide path angle was obtained from the difference between attitude and incidence measurements. One day they landed without retracting the pole. Directional oscillation tests were completed successfully and an advance report was issued (10 pages of typescript) by Pinsker and Lugner fo D.V.L." /6/

"The essence of the results was that the lateral oscillation was of abnormally long period – about 8 sec. At 250 km/h and damped out in about 5 cycles. At low speeds the oscillation was of “dutch roll” type but at high speed very little banking occurred. Many fierce arguments took place at D.V.L. on desirable directional stability characteristics , the Hortens naturally joining the “long period” school of thought. They claimed that the long period would enable the pilot to damp out any directional swing with rudder and keep perfectly steady for shooting. It was found that by using both drag rudders simultaneously when aiming, the aircraft could be kept very steady with high damping of any residual oscillation." /6/

"Lateral control was apparently quite good with very little adverse yaw." /6/

"Longitudinal control and stability was more like a conventional aircraft than any of the preceding Horten types and there was complete absence of the longitudinal "wiggle" usually produced by flying through gusts. Tuft tests were done to check the stall but the photographs were not good enough for much to be learned. Handling was said to be good at the stall, the aircraft sinking on an even keel. There seems to be some doubt, however, as to whether a full stall had ever taken place since full tests with varying CG and yaw had not been done. Although the stick was pulled hard back, the CG may have been too far forward to give a genuine stall." /6/

"Directional stability was said by Scheidhauer to be very good, as good as a normal aircraft. He did not discuss this statement in detail as he was obviously very hazy about what he meant by good stability and could give very little precise information about the type and period of the motion compared with normal aircraft." /6/

Me 163 Komet

"Scheidhauer had flown the Me 163 as a glider and was obviously very impressed with it; he was confident enough to do rolls and loops on his first flight. We asked him how the Horten IX V.1 compared with the 163; he was reluctant to give an answer and said the two were not comparable because of the difference in size. He finally admitted that he preferred the 163 which was more maneuverable, and a delight to fly (he called it “spielzeug”)." /6/

"The Horten IX V.2 with jet engines was flown only by Ziller and completed about 2 hours flying before its crash. This occurred after an engine failure – the pilot undershot, tried to stretch the glide and stalled. One wing must have dropped, for the aircraft went in sideways and Ziller was killed. Before the crash a demonstration had been given against an Me 262; Horten said the H IX proved faster and more maneuverable, with a steeper and faster climb." /6/

"In spite of the crash, Horten thought the single engine performance satisfactory and said the close spacing of the jets made single engined flying relatively simple." /6/

Video about Horten glider tests 1935

(This text is not a political statement, but rather a source of historical information. It is to be a reference for Aviation enthusiats, and not taken as an expression of sympathy for any Neo-Nazi or Right wing hate Group.)

REFERENCES

/1/ http://en.wikipedia.org/wiki/Horten_Ho_229#Northrop-built_reproduction

/2/ http://www.nurflugel.com/Nurflugel/Horten_Nurflugels/horten_nurflugels.html

/3/ http://www.nurflugel.com/Nurflugel/Horten_Nurflugels/ho_ix/ho_ix_blurb/body_ho_ix_blurb.html

/4/ http://blog.nasm.si.edu/2011/06/24/preserving-and-displaying-the-%E2%80%9Cbat-wing-ship%E2%80%9D/

/5/ http://www.globalsecurity.org/military/facility/tejon-ranch.htm

/6/ The Horten Tailless Aircraft by K.G. Wilkinson, B.Sc. D.I.C.
http://www.twitt.org/Farnborough_05.html

/7/ http://jpcolliat.free.fr/ho9/ho9-1.htm

/8/ http://wwiiarchives.net/servlet/document/index/115/0

/9/ http://en.wikipedia.org/wiki/Gothaer_Waggonfabrik

/10/ http://home.arcor.de/heuer.c/gothawagen/vorgaenger/gotha1883.html

/11/ http://wwiiarchives.net/servlet/document/index/115/0

/12/ http://de.wikipedia.org/wiki/Gothaer_Waggonfabrik

/13/ Some drawings Arthur L. Bentley: http://www.albentley-drawings.com/

/14/ Some pictures: http://www.luftarchiv.de/

/15/ http://www.fundinguniverse.com/company-histories/Textron-Lycoming-Turbine-Engine-Company-History.html

* * *

Avro Canada CF-105 Arrow

2011-10-30T16:58:00.000Z

"The Avro Canada CF-105 Arrow was a delta-winged interceptor aircraft, designed and built by Avro Aircraft Limited (Canada) in Malton, Ontario, Canada, as the culmination of a design study that began in 1953. Considered to be both an advanced technical and aerodynamic achievement for the Canadian aviation industry, the CF-105 held the promise of Mach 2 speeds at altitudes exceeding 50,000 ft (15,000 m), and was intended to serve as the Royal Canadian Air Force's (RCAF) primary interceptor in the 1960s and beyond." /1/

Nice video about AVRO Arrow design and construction early 1950's.

RESOURCES

/1/ http://en.wikipedia.org/wiki/Avro_Canada_CF-105_Arrow

* * *

Small "Solar" Turbines

2011-10-29T05:54:00.004+01:00

An interesting Solar turbine T62 (usually an APU) and its use in a small helicopter. /1/

Solar T62-16B 75 hp Turbine

T62-32 only 142 Ibs / 65 kg (dry)

T62-32 in a helicopter

T62-32 in a helicopter (160shp/61,091 rpm/sea level)

REFERENCES

/1/ http://www.propeng.com.au/catalog/product_info.php?cPath=&products_id=182

/2/ http://www.technologie-entwicklung.de/Gasturbines/Solar_T-62/solar_t-62.html

* * *

Launch Date Today; Galileo IOV 2 First Satellites

2011-10-20T20:38:00.010+01:00

Galileo IOV (In Orbit Validation) 2 first satellites should be launched today or tomorrow in Guiana Space Centre, French Guiana using Russian Soyuz ST-B launcher with Fregat-MT upper stage. /1/

Galileo IOV Satellite

These 2 satellites are the first two satellites of the actual Galileo system consisting of 30 satellites. Until now different tests have been going on with preliminary type Galileo satellites.

Satellites waiting on a Soyuz launch vehicle to be launched

Soyuz - Galileo IOV launch delayed

At the moment: 20 October 2011, following an anomaly detected during fueling of the Soyuz launcher’s third stage, the final countdown has been interrupted. Soyuz and its two Galileo IOV satellites, along with the launch facility, have been placed in a safe mode. A new launch date will be announced later today. /2/

And here it goes

Here is more about the Galileo and factors affecting its accuracy.

RESOURCES

/1/ http://www.esa.int/SPECIALS/Galileo_IOV/SEM7DEITPQG_0.html

/2/ http://www.esa.int/SPECIALS/Galileo_IOV/

* * *

Saturn Fly-through

2011-10-15T18:14:00.005+01:00

"The following video is not some CGI or 3D models but the real space how it is, only Cassini photographs used." /1/

5.6k Saturn Cassini Photographic Animation from stephen v2 on Vimeo.

"The above captivating natural color view was created from images collected shortly after Cassini began its extended Equinox Mission in July 2008. It can be contrasted with earlier images from the spacecraft's four-year prime mission that show the shadow of Saturn's rings first draped high over the planet's northern hemisphere, then shifting southward as northern summer changed to spring (see PIA06606 and PIA09793). During this time, the colors of the northern hemisphere have evolved from azure blue to a multitude of muted-colored bands." /2/

Cassini's position 15.10.2011 (CGI image). Launch date was 15.10.1997 (exactly 14 years before this position)

More about the source:
http://photojournal.jpl.nasa.gov/catalog/PIA11141

RESOURCES

/1/ http://www.outsideinthemovie.com/

/2/ http://photojournal.jpl.nasa.gov/catalog/PIA11141

/3/ http://ciclops.org/?js=1

* * *

Yuneec 81 hp (60 kW) Direct Drive Brushless DC Motor (and Some Testing)

2011-10-14T23:35:00.008+01:00

With low rpm (2400 1/min) this is an interesting direct propeller drive motor for the next generation fully electric aircraft. On top of all you get the whole power pack from the same company, including motors, controllers, chargers and batteries.

Here is more information:

http://www.yuneec.com/PowerMotor_Tech_spec.html

Here is an interesting video about a kit been tested in an old VW.

and an other controller driving 3-phase AC motor from DC.

in an airplane application you might not want to have any shutdown circuits even if the drive might be getting hot .. you just slow down so much that the circuit cools down and give a warning light.

* * *

English Electric Canberra

2011-10-14T14:56:00.009+01:00

E. E. Canberra is a bomber and spy plane with an exceptionally long service history.

"Evidence of the importance of Kapustin Yar (V-2 test site in Soviet Union) was obtained by Western intelligence through debriefing of returning German scientists and spy flights. The first such flight reportedly took place in mid-1953 using a high flying Canberra aircraft of the RAF. Numerous circumstantial reports suggest this flight took place, using either a Canberra B2 or a PR3, but the UK Government has never admitted such a flight took place nor have any of the supposed participants provided direct evidence" /1/

Here is some information about the airplane.

REFERENCES

/1/ http://en.wikipedia.org/wiki/Kapustin_Yar

* * *

Apollo Guidance Computer (AGC) Software

2011-10-12T12:51:00.409+01:00

"By 1963, designers determined that the Apollo computer software would have a long list of capabilities." /1/

Tasks of LEM's AGC

"The software should act as backup to the Saturn booster (Saturn had its own computer, the Saturn Launch Vehicle Digital Computer [LVDC], and software), controll aborts, target, do all navigation and flight control tasks, attitude determination and control, digital autopilot tasks, and eventually all maneuvers involving velocity changes. Programs for these tasks had to fit in the memories of two small computers, one in the CM and one in the LEM. Designers developed the programs using a Honeywell 1800 computer and later an IBM 36O, but never with the actual flight hardware which was only used for testing in some simulated environments. The development computers generated binary object code and a listing. The tape containing the object code would be tested and eventually released for core rope manufacture. The listing served as documentation of the code." /1/

Honeywell 1800 (1960's)

"Defining requirements is the single most difficult part of the software development cycle. The specification is the customer's statement of what the software product is to do. Improperly prepared or poorly defined requirements mean that the resulting software will likely be incomplete and unusable. Depending on the type of project, the customer may have little or a lot to do with the preparation of the specification. In most cases, a team from the software developers works with the customer." /1/

IBM 360 (1964...)

"MIT worked closely with NASA in preparing the Guidance and Navigation System Operations Plan (GSOP), which served as the requirements document for each mission. NASA's Mission Planning and Analysis Division (MPAD) at the Manned Spacecraft Center provided detailed guidance requirements right down to the equation level." /1/

Johnson Manned Spacecraft Center

"Often these requirements were in the form of flow charts to show detailed logic. The division fashioned these requirements into a controlled document that contained specific mission requirements, preliminary mission profile, preliminary reference trajectory, and operational requirements for spacecraft guidance and navigation. NASA planned to review the GSOP at launch minus 18 months, 16 months, 14 months and then to baseline or "freeze" it at 13.5 months before launch. The actual programs were to be finished at launch minus 10.5 months and tested until 8 months ahead, when they were released to the manufacturer, with tapes also kept at MIT and sent to Houston, North American (CM manufacturer), and Grumman (LEM manufacturer) for use in simulations. At launch minus 4 months the core ropes were to be completed and used throughout the mission." /1/

A video from the Mission Planning and Analysis Division of the Manned Spacecraft Center in Houston, Texas (now the Johnson Space Center [JSP]).

"Even during the early 1960s, the cycle of requirements definition, design, coding, testing, and maintenance was followed, if not fully appreciated, by software developers. The main point of the Bellcomm report (and the thrust of software engineering) was that software can be treated the same way as hardware, and the same engineering principles can apply." /1/

David G. Hoag, technical design director at the MIT laboratory, examines the IMU (Inertial Measuring Unit) of Apollo.

"However, NASA was more used to hardware development than to large-scale software and, thus, initially failed adequately to control the software development. MIT, which concentrated on the overall guidance system, similarly treated software as a secondary occupation. This was so even though MIT manager A.L. Hopkins had written early in the program that "upon its execution rests the efficiency and flexibility of the Apollo Guidance and Navigation System". Combined with NASA's inexperience, MIT's non-engineering approach to software caused serious development problems that were overcome only with great effort and expense. In the end NASA and MIT produced quality software, primarily because of the small-group nature of development at MIT and the overall dedication shown by nearly everyone associated with the Apollo program." /1/

A video from the Mission Planning and Analysis Division of the Manned Spacecraft Center in Houston, Texas (now the Johnson Space Center [JSP]).

"In the Apollo program, with an outside organization developing the software, NASA had to provide for quality control of the product. One method was a set of standing committees; the other was the acceptance cycle." /1/

Dr. Von Braun, Dr. J.P. Kuettner and Warren J. Northleft at the NASA Manned Spacecraft Center, now the Johnson Space Center (Oct.14.1964)

"Three boards contributed directly to the control of the Apollo software and hardware development. The Apollo Spacecraft Configuration Control Board monitored and evaluated changes requested in the design and construction of the spacecraft itself, including the guidance and control system, of which the computer was a part. The Procedures Change Control Board, chaired by Chief Astronaut Donald K. Slayton, inspected items that would affect the design of the user interfaces. Most important was the Software Configuration Control Board, established in 1967 in response to continuing problems and chaired for a long period by Christopher Kraft. It controlled the modifications made to the on-board software. All changes in the existing specification had to be routed through this board for resolution. NASA's Stan Mann commented that MIT "could not change a single bit without permission"." /1/

Dr. Von Braun looking computer consoles (Oct.14.1964)

"NASA also developed a specific set of review points that paralleled the software development cycle. The Critical Design Review (CDR) resulted in acceptance of specifications and requirements for a given mission and placed them under configuration control. It followed the preparation of the requirements definition, guidance equation development, and engineering simulations of the equations. Next came a First Article Configuration Inspection (FACI). Following the coding and testing of programs and the production of a validation plan, it marked the completion of the development stage and placed the software code under configuration control. After testing was completed, the Customer Acceptance Readiness Review (CARR) certified that the validation process resulted in correct software. After the CARR, the code would be released for core rope manufacture. Finally the Flight Readiness Review (FRR) was the last step in clearing the software for flight. The acceptance process was mandatory for each mission, providing for consistent evaluation of the software and ensuring reliability." /1/

"With respect to units, the LGC was eclectic. Inside the computer we used metric units, at least in the case of powered-flight navigation and guidance. At the operational level NASA, and especially the astronauts, preferred English units. This meant that before being displayed, altitude and altitude-rate (for example) were calculated from the metric state vector maintained by navigation, and then were converted to feet and ft/sec. It would have felt weird to speak of spacecraft altitude in meters, and both thrust and mass were commonly expressed in pounds. Because part of the point of this paper is to show how things were called in this era of spaceflight, I shall usually express quantities in the units that it would have felt natural to use at the time." (Don Eyles) /3/

"In software engineering practice today, the specification document is followed by a design document, from which the coding is done. Theoretically, the two together would enable any competent programmer to code the program. The GSOPs contained characteristics of both a specification and design document. But, as one of the designers of the Apollo and Shuttle software has said, "I don't think I could give you the requirements for Apollo and have you build the flight software". In fact, the plans varied both in what they included and in the level of detail requirements. This variety gave MIT considerable latitude when actually developing the flight software, thus reducing the chance that it would be easily verified and validated." /1/

The AGC Operating System

"The AGC was a priority-interrupt system capable of handling several jobs at one time. This type of system is quite different from a round-robin executive. In the latter programs have a fixed amount of time in which to run before being suspended while the computer moves on to the remaining pending jobs, thus giving each job the same amount of attention. A priority-interrupt system is always executing the one job with the highest priority; it then moves on to others of equal or lower priority in its queue." /1/

AGC and DSKY

"The Apollo control programs included two related to job scheduling: the Executive and the Waitlist. The Executive could handle up to seven jobs at once while the Waitlist had a limit of nine short tasks. Waitlist tasks had execution times of 4 milliseconds or less. If a task ran longer than that, it would be promoted by the Waitlist to "job" status and moved to the Executive's queue. The Executive checked every 20 milliseconds for jobs or tasks with higher priorities than the current ones. It also managed the DSKY displays88. If the Executive checked the priority list and found no other jobs waiting, it executed a program called DUMMY JOB continuously until another job came into the queue." /1/

AGC's placement in the LM

"The Executive had other duties as part of controlling jobs. One solution to the tight memory in the AGC was the concept of time-sharing the erasable memory. No job had permanent claim to any registers in the erasable store. When a job was being executed, the Executive would assign it a "coreset" of 12 erasable memory locations. Also, when interpretive jobs were being ran (the Interpreter is explained below), an additional 43 cells were allocated for vector accumulation (VAC). The final lunar landing programs had eight coresets in the LEM computer and just seven in the CM. Both had five VACs. Moreover, memory locations were given multiple assignments where it was assured that the owning processes would never execute at the same time. This approach caused innumerable problems in testing as software evolved and memory conflicts were created due to the changes." /1/

Programming Tools

"The AGCs in the LM and CM were programmed in two languages. The one we called "Basic", but more properly "Yul", was an assembler language of about 40 operations, authored by Hugh Blair-Smith. "Interpretive" was a list-processing interpretive language (essentially a set of subroutines) designed to facilitate guidance and navigation calculations involving double precision (30-bit fixed-point) vectors and matrices — at the cost of being very slow. The Interpreter was written by Charles Muntz." /3/

"The memory-cycle time for the AGC was 11.7 microseconds. A single-precision addition in the assembler language took two memory cycles. A double-precision vector cross-product programmed in Interpretive took about 5 milliseconds. One of the challenges in programming the AGC was juggling the two languages to obtain the best blend of speed and compactness for the given situation." /3/

"The interpreter got a starting location in memory, retrieved the data in that location, and interpreted the data as though it were an instruction. Instead of having only the 11 instructions available in assembler, up to 128 pseudo instructions were defined. The larger number of instructions in the interpreter meant that equations did not have to be broken down excessively. This increased the speed and accuracy of the coding." /1/

Some of the MIT staff /3/

"The MIT staff gave the resulting computer programs a variety of imaginative names. Many, such as SUNDISK, SUNBURST, and SUNDIAL, related to the sun because Apollo was the god of the sun in the classical period. But the two major lunar flight programs were called COLOSSUS and LUMINARY. The former was chosen because it began with "C" like the CM, and the latter because it began with "L" like the LEM97. Correspondence between NASA and MIT often shortened these program names and appended numbers. For example, SOLRUM55 was the 55th revision of SOLARIUM for the AS501 and 502 missions. BURST116 was the 116th revision of SUNBURST98. Although these programs had many similarities, COLOSSUS and LUMINARY were the only ones capable of navigating a flight to the moon. On August 9, 1968, planners decided to put the first released version of COLOSSUS on Apollo 8, which made the first circumlunar flight possible on that mission." /1/

Restart Protection

"An Apollo restart transferred control to a specified address, where a program would begin that consulted phase tables to see which jobs to schedule first. These jobs would then be directed to pick up from the last restart point. The restart point addresses were kept in a restart table. Programmers had to ensure that the restart table entries and phase table entries were kept up to date by the software as it executed. The restart program also cleared all output channels, such as control jet commands, warning lights, and engine on and off commands, so that nothing dangerous would take place outside of computer control ." /1/

"A software failure causing restarts occurred during the Apollo 11 lunar landing. The software was designed to give counter increment requests priority over instructions. This meant that if some item of hardware needed to increment the count in a memory register, its request to do so would cause the operating system to interrupt current jobs, process the request, and then pick up the suspended routines. It had been projected that if 85,000 increments arrived in a second, the effect would be to completely stop all other work in the system. Even a smaller number of requests would slow the software down to the point at which a restart might occur. During the descent of Apollo 11 to the moon, the rendezvous radar made so many increment requests that about 15% of the computer systems resources were tied up in responding. The time spent handling the interrupts meant that the interrupted jobs did not have enough computer time to complete before they were scheduled to begin again. This situation caused restarts to occur, three of which happened in a 40-second period while program P64 of LUMINARY ran during descent106. The restarts caused a series of warnings to be displayed both in the spacecraft and in Mission Control. Steven G. Bales and John R. Garman, monitoring the computer from Mission Control, recognized the origin of the problem. After consultation, Bales, reporting to the Flight Director, called the system GO for landing. They were right, and the restart software successfully handled the situation. The solution to this particular problem was to correct a switch position on the rendezvous radar which, through an arcane series of circuitry, had caused the analog-to-digital conversion circuitry to race up and down. This incident proved the need for and effectiveness of built-in software recovery for unknown or unanticipated error conditions in flight software-a philosophy that has appeared deeply embedded in all NASA manned spaceflight software since then." /1/

"Cut to a time about a year before Apollo 11, when we software engineers, who thought we already had enough to do, were requested to write the lunar landing software in such a way that the computer could literally be turned off and back on without interrupting the landing or any other vital maneuver! This was called "restart protection". Other factors than power transients also caused restarts. A restart was triggered if the hardware thought the software was in an endless loop, or if there were a parity failure when reading fixed memory, or for several other reasons. Restart protection was done by registering way points at suitable points during the operation of the software such that if processing happened to jump back to the last way point, no error would be introduced." /3/

"Following a restart, such computations could be reconstructed. For each job, processing would commence at the last registered waypoint. If multiple copies of the same job were in the queue, only the most recent was restarted. Certain other computations that were not considered vital were not restart-protected. These would simply disappear if there were a restart." /3/

"Restart protection worked very well. On the control panel of our real-time "hybrid" simulator in Cambridge was a pushbutton that caused the AGC to restart. During simulations we sometimes pushed the button randomly, almost hoping for a failure that might lead us to one more bug. Invariably, once we got the restart protection working, operation continued seamlessly." /3/

SDS 9300 digital computer and a COMCOR CI 5000 analog computer

"The hybrid simulator in Cambridge combined SDS 9300 digital and Beckman 21331 analog computers with a real AGC and realistic LM and CM cockpits."/3/

Conclusion

"NASA did successfully land a man on the moon using programs certifiably adequate for the purpose. No one doubted the quality of the software eventually produced by MIT nor the dedication and ability of the programmers and managers at the Instrumentation Lab. It was the process used in software development that caused great concern, and NASA helped to improve it143. The lessons of this endeavor were the same learned by almost every other large system development team of the 1960s: (a) documentation is crucial, (b) verification must proceed through several levels, (c) requirements must be clearly defined and carefully managed, (d) good development plans should be created and [53] executed, and (e) more programmers do not mean faster development. Fortunately, no software disasters occurred as a result of the rush to the moon, which is more a tribute to the ability of the individuals doing the work than to the quality of the tools they used." /1/

REFERENCES

/1/ http://history.nasa.gov/computers/Ch2-6.html

/2/ http://www.ibiblio.org/apollo/LVDC.html

/3/ http://www.doneyles.com/LM/Tales.html

/4/ E-2066, HYBRID SIMULATION OF THE APOLLO GUIDANCE, NAVIGATION AND CONTROL SYSTEM, Philip G. Felleman, December 1966

* * *

ACES II Ejection Seat

2011-10-09T22:07:00.007+01:00

"The ACES II (Advanced Concept Ejection Seat) is considered a smart seat since it senses the conditions of the ejection and selects the proper deployment of the drogue and main parachutes to minimize the forces on the occupant. The seat is a derivative of the Douglas Escapac seat. Removal from the aircraft is by a three part pyrotechnic sequence. A gun catapult provides the initial removal of the seat from the aircraft. A rocket sustainer provides zero/zero capability to the seat. To prevent the seat from tumbling when the aircraft is in a roll maneuver or there is a center of gravity imbalance, another (smaller) rocket called a STAPAC is attached to a gyroscope. This senses the motion and attempts to keep the seat from spinning by automatically providing a correcting force.

F-16 ejection sequences

Once clear of the aircraft, the pitot - static system on the seat measures the conditions and selects one of three operating modes depending on the conditions present at egress."

"Mode 1 - Low speed (<250 knots) and low altitude (<15 000 feet) operation. The main parachute deploys as the seat clears the rails. Drogue parachute remains undeployed to prevent line tangle."

"Mode 2 - Moderate speed (250-650 knots) and low altitude (<15 000 feet) operation. Drogue parachute deploys as the seat leaves the rails. Main parachute deploys 0.8 to 1.0 seconds after the drogue. Drogue chute is then released to prevent line tangle."

"Mode 3 - High speed (250-650 knots) and high altitude (>15 000 feet) operation. Drogue parachute deploys as the seat leaves the rails. The pitot - static system senses the conditions and delays the main parachute until mode 2 conditions are met. Then the main parachute deploys after 0.8 to 1.0 seconds. Drogue chute is then released to prevent line tangle. " /3/

ACES II parts and controls

"The Advanced Concept Ejection Seat (ACES) Was developed to provide a standard Ejection seat to be utilized in all United States Air Force jets from the mid-1970s. It was first flown in a A-10 Thunderbolt II from the Fairchild Republic Co. at the Farmingdale Long Island (N.Y.) plant in April 1978. The driving reasons for the development of the ACES II were to standardize on one type of ejection seat*- this would lead to reduction in training of both mechanics and pilots, also the design was intended to provide better performance in low altitude/adverse attitude conditions as well as to improve high speed seat stablity. It also allowed the government to purchase larger lots of spare parts." /1/

http://www.lifesupportintl.com/products/ACES_II_Ejection_Seat_Survival_Kit_SSK_Upgrade-1596-282.html

"The ACES-II ejection seat produced by McDonnell Douglas Aerospace is the seat installed in the F-16. The same seat is also used in the F-15, F-22, F-117 and A-10 but has small differences, mainly because the F-16 has the flightstick located at the right side, while the other aircraft have the stick located at the center, between the pilot's legs." /2/

"The ACES-II is a Zero-Zero seat. That means that the seat is still capable of ejecting the pilot at a 0 kts speed. The seat has the following parts: the case itself, the control-electronics, the parachute container that holds the pilot's parachute, the survival kit assembly according to the area of operation, the emergency oxygen assembly and the ejection mechanism itself." /2/

"The seat is installed in the cockpit in a 30 deg. angle. This position allows the pilot a better resistance to pulled G's as the position is not completely vertical." /2/

REFERENCES

/1/ http://www.ejectionsite.com/acesii.htm

/2/ http://www.xflight.de/pe_org_par_ace.htm#Elements

/3/ http://www.avitop.com/interact/ejection.htm

/4/ http://www.clubhyper.com/reference/acesiiss_1.htm

* * *

Apollo Guidance Computer (AGC), Its Emulators (ISAGC) and Space Environment Simulators

2011-10-09T16:32:00.031+01:00

Apollo AGC

"Early in the development of the Apollo simulators, a problem arose that would have had critical consequences if not solved. The importance of the on-board computer to the guidance and navigation of a moon-bound spacecraft was obvious. Crews interacted with the computer thousands of times in a typical mission; its keyboards contained the most used switches in the spacecraft." /1/

Eldon C. Hall with an Apollo Guidance Computer

"In August 1961, NASA contracted the MIT Instrumentation Laboratory (later called the Charled Stark Draper Laboratory) to develop the Apollo guidacnce, navigation and control system. Eldon C. Hall (shown above) was selected to lead the development team, and astronaut David Scott was chosen as the interface between the designers and the users." /8/

David Scott

"Between 1963 and 1969, Raytheon Corporation churned out approximately 75 rectangular chunks of metal, plastic, and silicon. Bigger than a breadbox but significantly smaller than a UNIVAC, the Apollo Guidance Computer had been designed by the MIT Instrumentation Laboratory to safely guide the Apollo astronauts and spacecraft to the Moon and back." /7/

AGC and DSKY (Display and Keyboard)

"Initially, the Apollo Guidance Computer (AGC) for both the command module and the lunar module were simulated functionally, just like the rest of the spacecraft hardware. This meant that the major components of the Apollo modules existed as software in a DDP-224 rather than in their physical form in the simulator." /1/

"The Apollo Guidance Computer (AGC) provided onboard computation and control for guidance, navigation, and control of the Command Module (CM) and Lunar Module (LM) spacecraft of the Apollo program. It is notable for having been one of the first IC-based computers." /2/

MIT AGC

MIT DSKY (pronounced "Diskey")

3C (Honeywell) DDP-224

"As a result of a study and the continued concern of the Apollo Spacecraft Project Office, W. B. Goeckler of the Systems Engineering Division of the program asked James L. Raney of Computational Analysis to do a feasibility study of using a Honeywell DDP-224 to simulate the AGC. Goeckler thought it might be possible to make the Honeywell computer think it was the MIT computer and execute the MIT code, thus eliminating the need for rewriting the programs and solving the time problem." /1/

"In 1966 3C (Computer Control Company) was sold to Honeywell, Inc. As the Computer Controls division of Honeywell, it introduced further DDP-series computers, including DDP-224." /3/

3C DDP-24 Computer (Later Honeywell)

3C (Computer Control Company) card rack 1964.

"Raney suggested both hardware and software modifications to the DDP-224. He specified a switch to disable the machine's floating-point capability. Instructions were added to enable more efficient table searching and other operations that the AGC did well. To handle the different word sizes, Raney let the right-most 14 bits of the DDP word be the value of a corresponding AGC word. The left-most bit was always set to zero to indicate that it was an Apollo word, and the intervening bits matched the sign bit of the original word. Words that could not be translated (i.e., executed one for one), had to be executed by interpretive subroutines written for the purpose and stored in the lower part of the Honeywell memory. Raney figured that since the DDP had a 10-to-1 advantage in execution speed over the AGC, several instructions could be used to do one Apollo instruction without slowing down the program. He used the index registers in the Honeywell DDP to act as the Fixed Bank Register, which kept track of which core rope memory module the AGC was currently using, as well as the address of the next instruction. Finally, to store the AGC code, the flight program was put in the upper half of the 64K words of core, with the interpreter used in the AGC to execute its own instructions in an area in lower core. The contents of the AGC's 2K erasable memory and the 8K of common core addressable by all the simulator computers also was in lower core, along with Raney's interpretive subroutines24." /1/

Video of the CM Computer Human Interface

"Despite Raney's careful evaluation of the situation and proposed solution, many Apollo project personnel opposed it, simply feeling it was unworkable. In desperation, NASA approved the attempt at an interpretive simulator and bought the modified computers. In the end, the simulation within a simulation was spectacularly successful. Even though Raney and his team took care to time the subroutines so that they matched execution of the actual Apollo code, the simulated computer was faster than the real article. Following the Apollo 9 earth-orbiting mission that tested the command module and lunar module rendezvous techniques, pilot Dave Scott complained that he had up to 12 seconds less time to react when the computer signaled for a maneuver to begin. This was adjusted for later flights." /1/

Video: NASA Computers 1960's

"The sidelight in here that I want to talk about is this Software Development Laboratory. There really wasn’t such a thing in Apollo. They had the computers that did simulation mainframes, they did their assembly language assembling on big machines. The crew trainer for Apollo, you know, the simulators that the astronauts train in, actually ran an interpretively simulated Apollo guidance computer. ISAGC it was called. A fellow named Jim [James L.] Raney, who was around for a long time, I think he’s still around somewhere, created that, ended up working all the way through Station, in fact, on onboard software." (John R. "Jack" Garman) /4/

Lunar Module AGC or LGC was located at the aft of LM

"I'd become so embedded in the Station Program that they sent some of that work with me, particularly the SSE project, and that gave me the opportunity to grab a couple of other people. One of them that would be very worthwhile chatting with is Jim [James L.] Raney. Jim was the guy that built the ISAGC, the Interpretively Simulated Apollo Guidance Computer." (John R. "Jack" Garman) /4/

DSKY was located in the middle of the front section

"Developing the interpretively simulated AGC had several impacts on the program. MIT could use the simulator as a field test of its code before flight. Since MIT used tape rather than core rope to send the programs to Houston and the Cape, errors discovered could be corrected and then the corrections tested in a "real" situation. Crews could react to the way the software worked with them. Also, the simulator cost just $4.6 million, compared to an estimated $18 million for functionally simulating the programs." /1/

DSKY in the lower middle

"Actually, the Apollo Mission Simulators were the last of their type in that the analog environment of the spacecraft that dictated hybrid and functional simulations changed to a digital environment that lent itself to full digital simulations for the Shuttle program. Evolution to full digital simulation, including digital imaging of window scenes, meant even more dependence on digital computers. Making the Shuttle a more autonomous and thus more complex spacecraft contributed to a massive increase in the size of the computer systems needed to support simulations." /1/

The AGC in the LM controlled almost everything simultaneously

AGC In-flight Use

"Shortly after liftoff of Apollo 12, two lightning bolts struck the spacecraft. The current passed through the command module and induced temporary power failure in the fuel cells supplying power to the AGC. During the incident the voltage fail circuits in the computer detected a series of power trenches and triggered several restarts. The computer withstood these without interruption of the mission programs or loss of data." /10/

Apollo 12 Struck by Lightning

"The Apollo 11 overload (1202 alarm) resulted from the rendezvous radar being set in the wrong mode during the lunar landing phase (?pilot in the loop?), waisting computer memory cycles and overloading it. The AGC operating system was responding to overloads as designed (lower priority tasks were delayed)." /10/

CM Simulator

"The Command/Service Module simulator (CSM) consists of a generalpurpose digital computer (SDS 9300) with 32K words of memory: two analog computer consoles (Beckman 21331, interface equipment (40 A/D, 56 D/A channels) and a complement of flight hardware (real and special-purpose simulators). The heart of the flight hardware is the on-board guidance computer (CMC) which contains the programs for guidance, navigation, and control of the spacecraft. In the simulator, a real CMC is used, but the fixed memory is replaced by a core rope simulator (which operates with the CMC and has all erasable memory). This allows modification of the flight programs before they are manufactured into modules. The entire contents of the fixed memory is recorded onto magnetic tape and can be loaded into the core rope simulator in a few minutes. Individual memory locations may be altered or monitored as well. This simulator also allows control of the CMC, by providing address stop, step-by-step operation, etc." /11/

SDS 9300 digital computer and a COMCOR CI 5000 analog computer

"The inertial measurment unit (IMU) is simulated by two devices, the gimbal angle simulator and the accelerometer simulator (PIPA simulator). The gimbal angle simulator accepts three dc inputs corresponding to the three gimbal angles (which relate the inertial axes to spacecraft orientation) and by means of three servos, positions the gimbal resolvers. These resolvers are interfaced to the coupling data units (CDU), as in the flight system, which digitize the gimbal angle information for the CMC. Each CDU also has a D/A section for converting CMC output to. either 800-cps or dc voltages for use in the system, e.g. to position the SPS engine, display attitude errors, position optics, etc. The accelerometers are simulated by a special purpose device which generates pulses to the CMC as a function of the applied input voltage (dc). This device interfaces directly with the CMC." /11/

Beckman EASE 2133

"The down-telemetry output and up-telemetry input of the CMC are interfaced through special purpose devices to the SDS 9300. For down telemetry, the device converts serial data to the parallel format which is acceptable to the SDS and these data are stored for later processing. The up-telemetry is generated in the SDS and serial pulses are sent to the CMC in the appropriate format. The uplink is used to intialize the CMC prior to a simulation." /11/

"Both the flight hardware and the hybrid computer are interfaced with a cockpit mockup which contains displays and controls. Many of the discrete input signals to the CMC originate in the cockpit, e.g. mode control, attitude and translation control, etc. In addition, the lower equipment bay of the cockpit contains the optics simulators and controls which provide star fields for navigation and alignment of the TMU. These optics simulators interface with the CMC through the CDU's." /11/

LM Simulator

"The Lunar Module (LM) simulator consists of essentially the same complement of equipment with certain other special-purpose devices added and the deletion of the optics simulator. In particular, rendezvous radar and landing radar simulators are used to generate radar data to the guidance computer (LGC) with the rendezvous radar angle data interfacing through the CDU. There is also a LM Visual Display device which projects a lunar landscape to the left window or the LM cockpit and which is driven by the SDS/Beckman computer. This device allows simulation of a manually controlled lunar landing maneuver with a realistic display of the scene as would be seen from the vehicle." /11/

Modern ISAGC

Here is a link to the virtual AGC which is a modern version of the original ISAGC.

http://www.ibiblio.org/apollo/

"Virtual AGC is a computer model of the AGC. It does not try to mimic the superficial behavioral characteristics of the AGC, but rather to model the AGC's inner workings. The result is a computer model of the AGC which is itself capable of executing the original Apollo software on (for example) a desktop PC. In computer terms, Virtual AGC is an emulator. Virtual AGC also provides an emulated AGS and (in the planning stages) an emulated LVDC. "Virtual AGC" is a catch-all term that comprises all of these." /5/

Modern AGC's

John Pultorak has constructed an AGC out of 74LS-series low-power Schottky TTL devices. Here is more about that.

http://www.spaceref.com/exploration/apollo/acgreplica/

John Pultorak's AGC

There are also other AGC's running today. Here are some links.

"The AGC is the most interesting early computer because: a) it flew the first men to the moon; and b) it's the world's first integrated circuit (IC, or microchip) computer. It also has interesting architectural features." (John Pultorak)

Apollo Guidance System Documents

You'll find more information here.

http://klabs.org/history/history_docs/mit_docs/index.htm

REFERENCES

/1/ Computers in Spaceflight: The NASA Experience, Chapter Nine, Making New Reality: Computers in Simulations and Image Processing

/2/ http://en.wikipedia.org/wiki/Apollo_Guidance_Computer

/3/ http://en.wikipedia.org/wiki/Computer_Control_Company,_Inc.

/4/ http://klabs.org/history/bios/garman/garman_oral_history.htm

/5/ http://www.ibiblio.org/apollo/index.html#What_Virtual_AGC_Is

/6/ http://klabs.org/history/apollo_11_alarms/eyles_2004/eyles_2004.htm

/7/ http://authors.library.caltech.edu/5456/1/hrst.mit.edu/hrs/apollo/public/histintro.htm

/8/ http://ed-thelen.org/comp-hist/vs-mit-apollo-guidance.html

/9/ http://history.nasa.gov/afj/aohindex.htm

/10/ http://klabs.org/history/history_docs/mit_docs/1707.pdf

/11/ E-2066, HYBRID SIMULATION OF THE APOLLO GUIDANCE, NAVIGATION AND CONTROL SYSTEM, Philip G. Felleman, December 1966

* * *

Apollo Simulators

2011-10-09T06:52:00.007+01:00

Apollo simulators and their associated computer systems were crucial to the success of the Apollo program. No less than 15 simulators trained crews during the Apollo Program.

Among the plethora of simulators, use of the Command Module Simulators and Lunar Module Simulators nonetheless occupied 80% of the Apollo training time of 29,967 hours.

Here are couple of interesting stories of that time and area.

http://history.nasa.gov/computers/Ch9-2.html

http://klabs.org/history/apollo_11_alarms/eyles_2004/eyles_2004.htm

And some videos:

Some more recent test videos.

* * *

Some Aircraft Design Tools

2011-10-05T09:46:00.003+01:00

Just did some Google search for "neutral point" calculation and found a list of sofrtware tools. So I'll open here a new page and reprint the list of aircraft design software for those it might be of some interest. We have to remember that there is actually no such thing as **free** software due to the fact that you have to learn to use it and fix all the problems associated with it's use etc.

The software list was originally in "IBIS RJ.03 CANARD EXPERIMENTAL HOMEBUILT AIRPLANE PROJECT's Software Links" which might also be an interesting project for somebody to read:

RJ.03 IBIS "The French Canard" homebuilt aircraft project. Building a wooden two-seater RJ.03 IBIS experimental airplane.

And here is the list again (remember that any software can have errors and bugs in it and you can never be 99.9% sure that the results are useful for you).

CEASIOM

The CEASIOM application is a free Conceptual Aircraft design tool on MATLAB. It was developed within the frame of the SimSAC (Simulating Aircraft Stability And Control Characteristics for Use in Conceptual Design) Specific Targeted Research Project (STREP) approved for funding by the European Commission 6th Framework Programme on Research, Technological Development and Demonstration.

CEASIOM runs under either Windows or Linux, and its only requires a MATLAB® license.

XFoil

XFOIL is an interactive program for the design and analysis of subsonic isolated single-segment airfoils. It was written at MIT by professor Mark Drela.

XFLR5 Airfoil and Wing analysis tool

XFLR5 uses XFOIL as its computation kernel and adds a graphical user interface for Windows operating systems. You still need the XFOIL manual to find your way around. XFLR5 also offers a 3D wing design capability, using two different calculation schems. The one similar to MIAReX (described further down below) uses the built in XFOIL kernel to determine local wing section properties. Highly recommended!

AVL - Athena Vortice Lattice Method

Yet another design program by professor Mark Drela and Harald Youngren. AVL is an extended vortice lattice method (VLM) software that supports aircraft configuration development by offering aerodynamic analysis, trim calculation and dynamic stability analysis, among other things.

MIAReX

A calculation method for Xfoil and multi-airfoil wings, based on formulae developed by James C. Sivells & Robert H. Neely in NACA TN-1269 (1947). Basically it takes 2D wing section data and integrates the various 2D section properties across the span to arrive at a 'semi-3D' solution.

TORNADO Vortex Lattice Method

A Vortex Lattice Method (VLM) implemented in MATLAB. The code is intended for linear aerodynamic wing design applications, in conceptual aircraft design or in aeronautical education. Among other things it can do such nice things as computing and displaying the Treffz plane velocity vector field. Known Cessna C-172 data was used to validate the code agains other codes such as AVL, VIRGIT and CMARC.

CalculiX A Free Software Three-Dimensional Structural Finite Element Program.

With CalculiX Finite Element Models can be build, calculated and post-processed. The pre- and post-processor is an interactive 3D-tool using the openGL API. The solver is able to do linear and non-linear calculations. Static, dynamic and thermal solutions are available. Both programs can be used independently.

Elmer

Elmer is an open-source computational tool for multi-physics problems (FEA/FEM/CFD). It has been developed in collaboration with Finnish universities, research laboratories and industry. Elmer includes physical models of fluid dynamics, structural mechanics, electromagnetics, heat transfer and acoustics.

* * *

Computer Mechanization of 6-DOF Flight Equations (1960's style)

2011-09-28T13:18:00.023+01:00

(http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19730061294_1973061294.pdf)

1. INTRODUCTION

Solution of the six-degree-of-freedom flight equations for aircraft and missiles continues to represent one of the most important application areas for analog, hybrid, and digital computer systems. Important computer requirements such as accuracy and speed are very much dependent on the choice of axis system for the translation equations of motion. In this connection it is well known that the flight-path axis system (or wind-axis system) makes much lower accuracy and speed demands on the computer than does the body-axis system. /1/, /2/

Flight-path or wind axis (w), stability axis (s) and body axis (b)

Despite this, a number of current computer mechanizations continue to use body axes for solving the translational equations of motion. Because of this, unnecessary demands on accuracy or frequency response are placed on the computer, and many mechanizations which could be all-analog or all-digital have shifted to hybrid implementation. Even if the mechanization is hybrid from the outset, there is considerable advantage to be gained by using an efficient axis system. The purpose of this paper is to point out again the advantages of flight path axes and to summarize the overall equation requirements for solving the six-degree of freedom flight equations.

2. BODY-AXIS TRANSLATIONAL EQUATIONS

For comparison, we present first the body-axis translational equations. The body axes Xb, Yb, and Zb are defined as a right-hand set fixed to the vehicle with the Xb axis along the longitudinal axis and the Zb axis directed downward for normal level flight. The components of the total vehicle velocity vector Vp along the Xb, Yb , and Zb axes, respectively, are Ub, Vb, and Wb (see figure 2.1).

The components of the body-axis angular velocity vector Ω (and hence the vehicle angular velocity vector) along the Xb, Yb, and Zb axes are Pb, Qb, and Rb, i.e., roll rate, pitch rate, and yaw rate, respectively. Here we assume Vp and Ω represent vehicle translational and rotational velocity vectors as viewed from an inertial (nonaccelerating) frame of reference. If we denote the external forces along a set of coordinate axes by X, Y, and Z, respectively, then Euler’s translational equations of motion, which are obtained by summing forces along the coordinate axes, are the following:

where m is the mass of the vehicle.

The inefficiency of these equations in body axes is immediately apparent when one considers the approximate size of the various terms. Let the vehicle be, say, a Mach 2 aircraft with Vmax = 2000 feet per second. A reasonable upper limit on pitch-rate Q, might be 2 radians per second. Thus, the term UbQb in equation (2.3) might be as large as 4000 ft/s2 or 125 g’s. On the other hand Zb/m, the normal acceleration due to the external force (primarily gravity and aerodynamic lift) may have an upper limit of several g’s. Hence artificial accelerations which are perhaps 20 to 50 times greater than the actual accelerations are introduced because of the high rotation rates which the body-axes experience. This means much less favorable computer scaling and hence much poorer solution accuracy for a given computer precision. Furthermore, the high-speed dynamics of the rotational equations are coupled into the translational equations, thus placing severe dynamic response requirements on the computer.

The use of flight-path axes greatly alleviates these problems. As we shall see in the next section, the flight-path axes allow a more efficient calculation of the aerodynamic angle of attack α (alpha) and the aerodynamic angle of side slip β (beta) than body axes allow. Using body axes and assuming that the ambient air mass is not moving relative to the inertial frame used to define Vp, then the following formulas can be used to obtain α, β, and velocity magnitude V, from the body-axis velocity components Ub, Vb, and Wb:

.

3. FLIGHT-PATH AXIS TRANSLATIONAL EQUATIONS

Next consider the flight-path axes Xw, Yw, Zw, shown in figure 3.1.

These differ from the body axes Xb, Yb, Zb by the angle of attack α and the angle of side slip β, as sh own in the figure. To rotate from body axes to flight-path axes one first pitches the body axes about Yb through -α. This defines an intermediate axis system Xs, Ys, Zs, called stability axes. One then yaws about Zs, through β, which defines the flight-path axes Xw, Yw, and Zw. Note that Vp is the Xw component of vehicle velocity; the Yw and Zw components are zero by definition. Let us define the Xw, Yw, and Zw components of flight-path angular velocity relative to inertial space by Pw, Qw, and Rw, and the components of external force along Xw, Yw, and Zw by Xw, Yw, and Zw, respectively. Then, since Uw = Vp and Vw = Ww = 0, the translational equations (2.1), (2.2), and (2.3) referred to the flight-path axes become

Solution of these three equations results in total velocity Vp, flight-path axis yaw rate Rw, and flight-path axis pitch rate Qw.

Next consider the formulas for α and β. Reference to figure 3.1 shows that α_dot is directed along Ys, with a component α_dot cos β along Yw. Thus α_dot cos β is equal to the difference between body-axis and flight-path axis angular rates along Yw. Therefore, from equation (3.3) we can write

where Pb_s is the body-axis (not stability axis) angular rate along Xs and is given by (3.5)

Similarly, reference to figure 3.1 shows that β_dot is directed along Zw and is equal to the difference between flight-path axis and body axis angular rates along Zw. Thus from equation (3.2) we get (3.6) where Rb_s is the body-axis angular rate along Zs and is given by (3.7). Note that Qb_s = Qb since the Yb body axis and Ys stability axis are coincident (3.8).

Equations (3.1), (3.4), and (3.6) can be integrated to yield total velocity Vp, angle of attack α, and angle of side slip β. They do not present the scaling difficulty of equations (2.1), (2.2), and (2.3) in the body axes. The body-axis velocity components Ub, Vb, and Wb can be obtained from Vp, α, and β by the formulas (3.9) -3.11). Similarly, the flight-path-axis forces Xw, Yw, and Zw can be derived from body-axis force components Xb, Yb, and Zb by the formulas (3.12)-(3.14) where Xs, Ys, and Zs are the intermediate stability-axis force components.

Frequently the aerodynamic force components are computed along stability axes, in which case the power plant and gravity forces, computed in body axes, would be resolved into stability axes where the aerodynamic forces are added; then the total forces would be resolved into flight-path axes to allow use of equations (3.1), (3.4), and (3.6).

It should be noted that we have assumed throughout this section that the translational and rotational velocity vectors are velocities relative to an inertial reference frame. If the atmosphere through which the vehicle is flying can be considered to be fixed with respect to this inertial frame, then the velocity magnitude Vp is the vehicle velocity relative to the atmosphere, and α and β represent the aerodynamic angle of attack and side slip, respectively. Using the approximation that the earth is flat, and with constant surface winds, it is possible to define the inertial reference frame as a frame attached to the atmosphere. Then all the formulas, as presented, are correct, and α, β and Vp can be used for computation of aerodynamic forces and moments.

Unfortunately, for a rotating spherical earth, axes fixed in the atmosphere are not inertial. If we consider such a frame to be inertial, we will make acceleration errors in equations (3.1), (3.2), and (3.3) of the order of V²/r0 where V is the vehicle velocity relative to an inertial frame with origin at the center of the earth and r0 is the radius of the earth. For illustration, consider a vehicle flying eastward in still air with a velocity Va relative to the atmosphere. Then V ~ Va + r0 ωn cos L, where ωn is the earth spin rate and L is the latitude. If the vehicle is flying westward, V ~ Va - r0 ωn cos L. For other headings V lies between these values.

For example, if Va = 3000 ft/s and L = 0 degrees, V ranges between approximately 1600 and 4400 ft/s. The corresponding acceleration error in equations (3.1), (3.2), and (3.3), given by V²/r0, ranges between approximately 0.1 and 1 ft/s2. For many flight vehicles this is a negligible error. On the other hand, for a supersonic transport cruising eastward at 3000 ft,/s this lowers the required steady-state lift by about 3per cent, which could lower the drag significantly and hence make a noticeable difference in maximum range.

There appears to the authors to be no simple way to take these accelerations into account and still use a flight-path axis system referenced to the atmosphere. One could add an approximate correction acceleration in the vertical direction given by V²/r0 to the translatory forces in equations (3.1), (3.2), and (3.3). In fact, one could further simplify the computation by adding the term only to equation (3.3), based on the argument that most of the time a supersonic aircraft will be in near-level flight at cruise and that a moderate acceleration error during transient conditions can be accepted.

In this case equation (3.3) becomes

Note that this equation will exhibit acceleration errors of the order of V²/r0 for conditions far from level flight.

4. ROTATIONAL EQUATIONS

The only reasonable axes to use for the rotational equations of motion are the body axes. If we let the external moment components along Xb, Yb, and Zb, be Lb, Mb, and Nb, respectively, then summation of moments about the three body axes of a body symmetrical about the XbZb plane leads to the equations:

Here Ixx, Iyy, and Izz are the moments of inertia about Xb, Yb, and Zb respectively, and Ixz is the product of inertia of the symmetrical body. Note in equations (4.1), (4.2), and (4.3) that the second term in each equation represents a nonlinear inertial coupling term. For flight vehicles such as large transport aircraft which do not generate relatively high angular rates these terms often can be neglected. For many flight vehicles the roll rate Pb has a maximum value which is considerably higher than pitch-rate Qb or yaw-rate Rb. Hence the QbRb term in equation (4.1 ) often can be neglected in comparison with the RbPb and PbQb terms in equations (4.2) and (4.3), respectively.

The third term in each of equations (4.1), (4.2), and (4.3) represents the effect of the product of inertia Ixz. If the x, y, z body axes have been chosen to be almost coincident with the principal axes, this term may be negligible in all three equations, since Izz will be very small compared with the principal moments of inertia. For relatively low angular rates the nonlinear terms (PbQb, Pb² - Rb², and QbRb) usually can be neglected and in any event Rb² frequently can be neglected as small compared with Pb² in equation (4.2).

5. COMPUTATION OF EULER ANGLES FOR A FLAT EARTH

Solution of equations (4.1), (4.2), and (4.3) results in computation of the body-axis angular velocity components Pb Qb, and Rb. These must be integrated a second time to obtain the orientation of the vehicle body axes with respect to the desired references axes, typically Euler axes which point north, east, and toward the center of the earth (Xe, Ye, and Ze in figure 5.1 ).

This orientation usually is expressed in terms of the conventional aircraft Euler angles, i.e., heading-angle Ψ (psi), pitch angle Θ (theta), and bank angle Φ (phi). These angles usually are computed from Pb, Qb and Rb by the following well-known equations:

Note that, since Pb, Qb, Rb are the body-axis components of the vehicle angular velocity relative to an inertial reference system, there is a small error introduced by the angular velocity of axes which point north, east, and down relative to a spherical earth. This small error can be corrected, if necessary, using equations (7.1)-(7.3) in the next section.

The well known singularity of the Euler angle system at Θ = ±π/2 can be avoided, if necessary, by computing direction cosines or quaternions /4/ instead of Euler angles, or by introducing a fourth angle. /3/

The use of quaternions rather than direction cosines should be considered if a system free of singularities is needed, since there are only four quaternions with a single redundancy as compared with nine direction cosines with six redundancies.

5.1 Additional notes about Euler angles /6/

The most popular application is to describe aircraft attitudes, normally using a Tait–Bryan convention so that zero degrees elevation represents the horizontal attitude. Tait–Bryan angles represent the orientation of the aircraft respect a reference axis system (world frame) with three angles which in the context of an aircraft are normally called Heading Ψ (psi), Elevation Θ (theta) and Bank Φ (phi). When dealing with vehicles, different axes conventions are possible.

Tait–Bryan Euler angles in aircraft application (all zero degrees yield normal flight attitude north)

When studying rigid bodies in general, one calls the xyz system space coordinates, and the XYZ system body coordinates. The space coordinates are treated as unmoving, while the body coordinates are considered embedded in the moving body. Calculations involving acceleration, angular acceleration, angular velocity, angular momentum, and kinetic energy are often easiest in body coordinates, because then the moment of inertia tensor does not change in time. If one also diagonalizes the rigid body's moment of inertia tensor (with nine components, six of which are independent), then one has a set of coordinates (called the principal axes) in which the moment of inertia tensor has only three components.

The angular velocity of a rigid body takes a simple form using Euler angles in the moving frame. Also the Euler's rigid body equations are simpler because the inertia tensor is constant in that frame.

"It is important to appreciate the range of the Euler angles:

−π ≤ ψ ≤ +π

−π/2 ≤ θ ≤ +π/2

−π ≤ φ ≤ +π

It is not obvious that pitch should be constrained to the range ±90◦. Consider a loop; as the pilot pulls up into the loop, the pitch increases to 80◦, then85◦, 86◦, 87◦, 88◦ and 89◦. At this point, the aircraft is still pointing forwards, but almost vertically upwards. In the next two degrees of motion, the aircraft passes through 90◦ and subsequently is pointing backwards, but at 89◦ to the horizon. Notice also that during this maneuverer, as the pitch angle passes through 90◦, the aircraft heading changes from forwards to backwards (an 180◦ instantaneous change in yaw) and also, the aircraft changes from upright to inverted (an 180◦ instantaneous change in roll)." /8/

German words: "Die Lage des körperfesten Achsensystems wird mit Hilfe der drei Eulerwinkel Ψ (Azimut, Gierwinkel), Θ (Längsneigung, Nickwinkel) und Φ (Hängewinkel, Rollwinkel) beschrieben." /7/

6. COMPUTATION OF VEHICLE POSITION FOR A FLAT EARTH

Once the orientation of the flight vehicle with respect to the Euler axes has been established e.g., by means of the Euler angles, then it is possible to compute the velocity north Ue, the velocity east Ve, and the velocity downward We, or its negative, the rate of climb h_dot. Direct integration then yields the vehicle position.

Determination of Ue, Ve, We is complicated by the fact that the vehicle velocity vector Vp lies along the x wind axis and therefore must be resolved from wind to earth axes. Unfortunately, the complete orientation of the wind axes is known only relative to body axes; hence it is necessary to perform the resolution of Vp into earth axes by first resolving it into body axes,. then from body axes to earth axes. The resolution of Vr from wind axes to body axes is accomplished by the transformation given in equations (3.9), (3.10), and (3.11 ).

The resolution of vehicle velocity from body axes to earth axes can be accomplished by using direction cosines. Thus let l1, l2, and l3 be the projections of a unit vector along the x body axis onto the Xe, Ye, and Ze earth axes, respectively. Similarly, let m1, m2, and m3 be the projections of a unit vector along the y body axis onto the Xe, Ye, and Ze earth axes, respectively. In the same way let n1, n2, and n3 be the projections of a unit vector the z body axis along the Xe, Ye, and Ze earth axes, respectively. Then by definition

It is easy to show that the direction cosines are related to Euler angles by the following formulas:

(Equivalent formulas for direction cosines in terms of quaternions are given in reference 4.)

An alternative mechanization of equations (6.1 ) through (6.6) avoids computation of the direction cosines by instead performing successive resolutions of the velocity components Ub, Vb, and Wb through the angles -Φ, -Θ, and -Ψ. Consider the intermediate axis system x’, y’, z’ in figure 5.1. Clearly the velocity components U’, V’, and W’ along x’, y’, and z’ are given by

Defining U", V", and W" as the velocity components along the intermediate axes x", y", and z", we have (6.8). Finally, from figure 4.1 we see (6.9).

Successive application of equations (6.7), (6.8), and (6.9) for U, V, and W to obtain Ue, Ye, and We requires fewer mathematical operations than using equations (6.1) through (6.6). It therefore has computational advantages using either an analog or digital mechanization. In computing ground coordinates from Ue and Ve in equations (6.1 ) and (6.2), or equation (6.9), it is important to note that Ue and Ve represent airspeed components north and east, respectively. To convert them to groundspeed components, the north component of wind Wz must be subtracted from Ue, and the east component of wind Wy must be subtracted from Ve. Thus if Sz and Sy represent distance traveled north and east, respectively, then

Equations (6.10) and (6.11) are valid only for steady winds, since the implicit assumption was made that axes stationary relative to the atmosphere are inertial. Equations (3.1), (3.2), and (3.3) are referred to inertial space and correction terms must be added if the reference axes are not inertial.

7. COMPUTATION OF VEHICLE EULER ANGLES AND POSITION FOR A ROTATING SPHERICAL EARTH

In the previous section we presented the formulas for computing vehicle position over a flat earth with steady winds. We can use the same position formulas to obtain velocity north Ue and velocity east Ve over a rotating spherical earth with radius r0 and angular rate ωN. However, Ue and Ve will represent airspeed components and must be corrected to yield groundspeed components Sx_dot and Sy_dot respectively. Furthermore, when a spherical earth is considered, it may be necessary to correct the vehicle angular rates used to compute Euler angles in order to take into account the rotating reference frame, as pointed out earlier in section 6. It can be shown that the body-axis components of the vehicle angular velocity relative to the Euler reference frame, Pbe, Qbe, Rbe are given by the following formulas: /5/

Here r is the radial distance of the vehicle from the center of the earth and is given by (7.4) where r0 is the radius of the earth and h is the vehicle altitude. In many cases we can substitute r0 for r in equations (7.1), (7.2), and (7.3) and still obtain sufficient accuracy.

The values of Pbe, Qbe, and Rbe in these equations are then used to compute the Euler angle rates. Thus by analogy with equations (5.1), (5.2), and (5.4)

In many cases the computations involved in equations (7.1), (7.2), and (7.3) can be neglected i.e., we can assume that Pbe ~ Pb, Qbe ~ Qb, Rbe ~ Rb. This is particularly true if the overall six-degree-of-freedom computation involves a control system (automatic or human) which attempts to maintain Ψ, Θ, and Φ at specified values. In any case the correction rates are the order of Vp/r0. For example, if Vp = 2000 ft/s, the correction rate is equal to approximately 0.005 degree per second. On the other hand, if the flight-vehicle problem includes a stable platform, the rate corrections given by equations (7.1), (7.2), and (7.3) may be important.

It should be noted that Sz_dot and Sy_dot in equations (7.1 ), (7.2), and (7.3) represent vehicle velocity components north and east, respectively, over the surface of a nonrotating earth with steady winds. On the other hand equations (6.1 ) and (6.2), or alternatively, equation (6.9), gives us Ue and Ve, i.e., vehicle velocity components north and east, respectively, relative to the inertial reference frame for the translational equations of motion. We made the approximation in section 3 that this reference frame is fixed relative to the ambient atmosphere. We can account for the linear velocity of the atmospheric reference frame (but not the angular velocity) by noting that relative to the surface of a nonrotating earth it is moving northward with the northerly component of wind and eastward with the sum of the rate due to earth spin and that due to eastward component of wind. Thus we can write the following equations:

It can also be shown /5/ that the time rate of change of latitude and longitude are given by the formulas (7.10) and (7.11).

It should be noted that motion of a flight-vehicle over a rotating earth can be treated exactly, /5/ but that the exact translational equations referred to axes fixed relative to the ambient atmosphere are very complicated. Thus many of the computer mechanization advantages for flight-path axes are lost, and the computation of α, β, and Vp is much less elegant. We have attempted in this section to describe how one can utilize the flight-path axis system and still correct approximately for the fact that the vehicle is flying over a rotating earth with surface winds. This approach should be adequate for all but the most exacting requirements, unless the vehicle reaches hypersonic speeds. For subsonic vehicles or supersonic vehicles traveling over relatively short distances the flat-earth equations in sections 3 through 6 should be adequate.

8. COMPUTATION OF AERODYNAMIC FORCES AND MOMENTS

Aerodynamic forces and moments for flight vehicles normally are computed in stability axes. Thus let Xa, Ya, and Za be the aerodynamic forces along the Xs., Ys, and Zs stability axes shown in figure 3.1. Here -Xa corresponds to drag D, and -Za corresponds to lift L.

In addition to aerodynamic forces the flight vehicle experiences propulsion and gravity forces. These are most conveniently defined in body axes. Let us denote the propulsion force components along the x and z body axes by Xp and Zp, respectively. The gravity force components along x, y, and z will by definition be mgl3, mgm3, and mgn3 respectively. The sum of the propulsive forces and gravity forces along body axes can then be resolved to stability axes, where the aerodynamic forces are added to obtain the total force component Xs, Ys and Zs along the stability axes. Using equations (6.4), (6.5), and (6.6) to express the direction cosines l3, m3, n3 in terms of Euler angles, we obtain:

Finally, reference to figure 3.1 shows that the force components Xw, Yw, and Zw along the flight-path axes can be computed using the formulas (8.4) - (8.6).

These force components are used to mechanize the translational equations given in section 3. If the aerodynamic forces are given in body axes rather than stability axes, the modification of equations (8.1 ), (8.2), and (8.3) is apparent.

The external moments acting on the flight vehicle consist of aerodynamic moments La, Ma, and Na, normally given in stability axes, and power plant moments Lp, Mp, and Np, given in body axes. The total moments L, M, and N in body axes become the following:

Again, if the aerodynamic moments are given in body axes, the simplification of equations (8.7), (8.8), and (8.9) is obvious (set α = 0). Figure 8.1 shows a block diagram of the over-all six-degree-of-freedom equations for the case of a flat earth.

Figure 8.1

L. E. FOGARTY

R. M. HOWE,

University of Michigan

(REPRINT of the original with minor fixes and additions.)

REFERENCES

/1/ Howe R M
Coordinate systems for solving the three-dimensional flight equations
WADC Technical Note 55-747 June 1956

/2/ Howe R M
Coordinate systems and methods of coordinate transformation for three-dimensional flight equations
Proceedings of the First Flight Simulation Symposium WSPG
Special Report 9 September 1957

/3/ Greenwood D T
An extended Euler angle coordinate system for use with all-altitude aircraft simulators
WADC Technical Report 60-372 August 1960

/4/ Robinson A C
On the use of quaternions in simulation of rigid-body motion
WADC Technical Report 58-17 December 1958

/5/ Fogarty L E, Howe R M
Analog computer solution of the orbital flight equations
SIMULATION vol 1 no 1 Fall 1963 pp R-41 through R-47

/6/ http://en.wikipedia.org/wiki/Euler_angles

/7/ http://tumb1.biblio.tu-muenchen.de/publ/diss/mw/2004/holzapfel.pdf

/8/ David Allerton,
PRINCIPLES OF FLIGHT SIMULATION, Department of Automatic Control and Systems Engineering, The University of Shefﬁeld

Flight Simulator or ICBM?

2011-09-24T04:27:00.012+01:00

You try to figure out what is the math inside a flight simulator and you end up with an intercontinental ballistic missile (ICBM).

The paper dates back to years 1959-1961 to the era when USA and Soviet Union were competing who is first to the space (and ICBM's). It is maybe partially influenced by the Mercury-Atlas rocket's autonomous guidance system which was used in 1962-63. The Atlas E and F had completely autonomous inertial guidance systems. Here is a link to the paper.

http://contrails.iit.edu/DigitalCollection/1961/ASDTR61-171volume03.pdf

Missiles had the first embedded computer systems. So we have to thank those early systems for the fact that we have now small microcomputers in every day use. The Minuteman-I Autonetics D-17 flight computer was used during 1960's. Autonetics was the associate contractor for the Minuteman (MM) guidance system, which included the flight and prelaunch software.

This software was programmed in assembly language into a D17 disk computer. TRW provided the guidance equations that Autonetics programmed and was also responsible for the verification of the flight software. When MM I became operational, the flight computer was the only digital computer in the system. The targeting was done at Strategic Air Command (SAC) Headquarters by the Operational Targeting Program developed by TRW to execute on an IBM 709 mainframe computer

* * *

Airplane's Body, Stability and Wind Axis

2011-09-21T04:35:00.009+01:00

Some preliminary notes

You should notice that what ever temporary alpha (angle of attack) or beta (angle of sideslip) is it has directly nothing to do with the flight path of the plane. Usually you use alpha and beta to control the amount of lift and side force the plane creates at any given moment. And after that when the force is created the plane might start to follow the given control and for example reduce these angles. So to say that alpha and beta are the steering angles but what the actual flight path will be is a different question.

What exactly is the airplane's stability axis?

It is the body axis when the angle of attack A.O.A or α (alpha) is zero. And you should not include the side slip β (beta) to that transformation. Here is an old picture which clarifies the definition.

"The body axis system is a right-handed set of mutually perpendicular axes whose origin is fixed with respect to the aircraft at the (35% M.A.C) point in the plane of symmetry. Aerodynamic forces and moments are given in terms of this fixed point. The x-stability axis is the projection of the velocity vector of the aircraft on the plane of symmetry. The angle between the velocity vector and the x-stability axis is defined as the slide slip β (beta). The angle between the x-stability axis and the x-body axis is defined as the angle of attack α (alpha). The z-stability axis is in the plane of symmetry of the aircraft.

The aircrafts manufacturer's aerodynamic data is usually presented in the stability axis system. This data is in the form of non-dimensional aerodynamic coefficients."

If you include the side slip in the system then it is the wind axis system. All three axes are shown in the following picture. The wind axis is also called the flight-path axis.

Wind (w), Stability (s) and Body (b) axis systems

Stability and Control Derivatives

There is a flight dynamics text book available from TU Delft, Delft, Nederland in the following link. It gives you methods to solve stability and control derivatives.

http://www.aerostudents.com/files/flightDynamics/flightDynamicsFullVersion.pdf

There is an Excel spreadsheet available that suppose to do the same from Cal Poly Flight Simulation Group, Aerospace Engineering Department, California Polytechnic State University, USA in the following links:

"Computes static and dynamic stability and control characteristics of aircraft based on geometric input. Implements DATCOM methods adapted from the Air Force as well as compiled solutions by Roskam."

http://aerosim.calpoly.edu/media/cms_page_media/15/Brad%20Beachler%20-%20SAD%20File%20Creator.pdf

http://aerosim.calpoly.edu/media/cms_page_media/15/Brad%20Beachler%20-%20SAD%20File%20Creator.xls

* * *

Orion Simulators and Mock-ups

2011-09-18T02:18:00.000+01:00

Some videos about the NASA Orion simulators and mock-ups.

* * *

How to Simulate Zero Gravity?

2011-09-17T23:46:00.008+01:00

If you need to simulate zero gravity you need to drop the simulator cabin. Obviously it is only possible to create a short period of zero gravity using this method on Earth. NASA's Vertical Motion Simulator does exactly that. Take a look at the following video.

VMS at NASA Ames

* * *

What is DAGR? (Newborn 1994 Magellan Trailblazer?)

2011-08-29T05:50:00.014+01:00

DAGR stands for Defense Advanced GPS Receiver (Rockwell Collins) and it looks much like my almost 20 years old and still running Magellan Trailblazer hand held GPS device. Seemingly DAGR has much more efficient battery and better display which were the weak points of Magellan Trailblazer.

DAGR

Also the slow start up of the Trailblazer was very annoying (it only had 8 channels). Once you had the first satellite position fix the batteries were empty and the unit said "good bye". So I hooked it up to my car battery and there it did a great job for many years. You could not see any moving map but I was able to get back to the same spot I had once entered in the memory of the unit.

(you could put the antenna outside your car using a cable)

("Searching" satellites, it really spent some time to find them)

Magellan Trailblazer handheld GPS device of the mid 90's
(the backdoor is "Gone with the Wind")

Magellan Trailblazer 1994

Vintage Magellan ad

DAGR seems to be much more efficient and it even can find any GPS jamming device if one is used near by.

More about DAGR can be found in the link below: This proves that if you have once invented a wheel it is hard to invent again.

http://www3.rockwellcollins.com/ecat/gs/DAGR.html

* * *

A Robot that Flies Like a Bird (FESTO)

2011-08-15T21:44:00.004+01:00

Finally it is reality - a machine that can fly like a bird! Very interesting development in the area of light structures and lithium polymer batteries.

Correcting James Cook's Map of the World 1784

2011-07-20T17:05:00.004+01:00

Captain James Cook FRS RN (7 November 1728 – 14 February 1779)

It is interesting to study how close to the truth James Cook actually was 1784 with his new map of the World.

Captain Cooks Map of the World, c. 1784

In the following picture the correct shore line is laid over the Cook's map. Blue arrows show the largest mistakes in the map. At that time the Antarctica was not yet known and it was assumed to be the Antarctic Ocean all together. Australia was called "New Holland" and it's west coast was shifted 300 km west. Similar shift can be detected with Central African west coast but 400 km east. Island's east coast was shifted and it was drawn 100 km too narrow. Russia's norhern parts were also less known. Tasmania was connected to the main land of Australia.

Same map compared to the actual shore line.

James Cook was know for his accurate mapping work and that is the reason so few errors exist on that map.

"Cook charted many areas and recorded several islands and coastlines on European maps for the first time. His achievements can be attributed to a combination of seamanship, superior surveying and cartographic skills, courage in exploring dangerous locations to confirm the facts (for example dipping into the Antarctic Circle repeatedly and exploring around the Great Barrier Reef), an ability to lead men in adverse conditions, and boldness both with regard to the extent of his explorations and his willingness to exceed the instructions given to him by the Admiralty."

Below is the description of the map:

"Captain Cooks Map of the World, c. 1784

"A New General Chart of the World", with Traces of Captain Cook's Voyages, by Conder

c. 1784, Map Print Entitled: "A NEW GENERAL CHART OF THE WORLD", Captain Cook's Map of the World, Engraved by T. Conder, Published by Alexander Hogg, London, England, Very Fine.
This uncolored copperplate engraving of the map of the world is titled "A NEW GENERAL CHART OF THE WORLD, Exhibiting the Discoveries made by Captn. James Cook in his First, Second, and Third Voyages; Within the Tracks of the Ships Under his Command." Measuring 15" x 19", including the wide margins, it also has engraved tracings of all three of Cook's voyages around the globe. The map has very light toning, some folds, and minor foxing.

James Cook (1728-1779) made three scientific and navigational voyages to the Pacific Ocean. Cook was the first to map Newfoundland prior to making three voyages to the Pacific Ocean during which he achieved the first European contact with the eastern coastline of Australia, the European discovery of the Hawaiian Islands, and the first recorded circumnavigation of New Zealand. He died in Hawaii in a fight with Hawaiians during his third exploratory voyage in the Pacific in 1779."

* * *

Yuneec E430 Electric Aircraft

2011-04-24T20:47:00.004+01:00

Another fully electric aircraft. Here are some videos and links.

Yuneec Electric Aircraft at Camarillo, CA from Tom Nalevanko on Vimeo.

* * *

Elektra One - New Battery Powered Airplane from Augsburg

2011-04-17T15:40:00.012+01:00

Continuing my series of battery powered flying there is a new plane Elektra One which just made it's maiden flight in Augsburg Germany (15.4.2011). Here are some links and videos of it.

* * *

New (Paraglider) Electric Motors and Controllers

2011-04-13T20:51:00.008+01:00

Some new ideas how to get more power to the propeller with less weight.

Werner Eck's motor

Electric Atos Hang Glider

This system gives 30 minute flight time and uses:

Electric Motor: PPSM - Brushless High Power Direct 10, without gearing, free of maintenance, developed by Dr. Ing. Werner Eck.

Controller: Motor Management System and Batterie Management system, developed by Geiger Engineering (Jochen Geiger).

Battery: 14 cells Lithium Ion Polymer, 31Ah, fast chargeable.

Propeller: Low Noise, high efficiency, 1.4 meter (55 inches) folded model developed by Dr. Ing. W. Eck. It spins at 1900 RPM.

Thrust: Static Thrust with "StartBoost" 61.5 kp (135 lbf), continuous 52.4 kp (116 lbf). Flight Thrust at 40 km/h (24.9 mph) 33.5 kp (73.8 lbf).

Weight: 21 kg (61.7 lbs) including battery, motor and harness. HG version weighs 28 kg.

Endurance: 30 minutes in still air with standard paraglider wing.

See also:
http://www.electricppg.com
http://www.geigerengineering.de/avionik/elektroantriebssystem/
http://www.flycocoon.com/
http://www.motorschirm-verband.de/forum/viewtopic.php?t=1052&sid=aa5f5dd0b335f7210e205aa7ea92bbbf
http://www.youtube.com/watch?v=y7xm4YE7y24&NR=1
http://www.youtube.com/watch?v=TMWyrzisRjY&feature=related

* * *

New Interesting Designs

2011-04-08T20:11:00.002+01:00

Here is a list of some new interesting designs:

Eagleeye by gyroscoop

First flight tests by gyroscoop

Helybaby Coax GYROSCOOP by gyroscoop

* * *

Konrad Zuse - the World's First Computers in 1930s

2011-03-25T11:50:00.033Z

Konrad Zuse

"In seeking to automate burdensome engineering calculations, the then 26 years old engineer Konrad Zuse developed a fully programmable mechanical calculating machine: the Z1, the world’s first computer. The machine operated with binary semilogarithmic floating-point numbers - something completely new - and the programs were developed using Boolean algebra. The original Z1 was destroyed in a bombing raid over Berlin. In 1989, Konrad Zuse reconstructed the Z1 for the German Museum of Technology."

"Today considered the Z1 is the first freely programmable computer of the world using Boolean logic and binary floating point numbers. It was completed in 1938 and financed completely from private funds."

"Several years before the Colossus in the U.K. and the ENIAC in the U.S., the Z3, built by Konrad Zuse in 1941, was crunching numbers in Germany. In a short article, the Register says the Z3 was the first programmable computer. Based on a binary floating-point number and switching system, it had all the attributes of today's computers, such as a control block, a memory, and a calculator. But it didn't have the ability to store the program in the memory together with the data because the memory was too small. It had a 64-word memory of 22 bits each and was able to handle four additions per second and to do a multiplication in about five seconds. And it was pretty big: five meters long, two meters high, and 80 centimeters wide. It was destroyed during WWII, and later rebuilt in 1960/1961."

"Zuse's machine saw use during the war, but not as a codebreaker. Instead it was used to perform statistical analysis of the stresses on aircraft wings, and in particular, a problem known as wing-flutter. This vibration of an aircraft's wing can cause a critical instability during flight. The calculations needed to overcome this design issue were incredibly complex, and it was this problem that the Z3 solved."

See also:

1914 Triodes as Logic Gates (see also) [Eric Tigerstedt] (video1 2)
1932 Drum Memory [Gustav Tauschek] (video)
1936 Computer Ideas: Turing, Zuse, Von Neumann, Church, etc.
1938 Zuse Z1 (video)
1938 Bomba / Bombe (video) [Enigma code breaker]
1941 Zuse Z3 (video)
1942 Atanasoff–Berry Computer (video)
1944 Colossus (video)
1946 ENIAC (video)
1948 Manchester Small-Scale Experimental Machine (Baby) (video)
1949 EDSAC Electronic Delay Storage Automatic Calculator (video)
1951 UNIVAC (video)
1951 Magnetic Core Memory (video)
1956 IBM 705 [tubes] (video)
1958 LGP 30 [tubes] (video)
1961 IBM 7030 [transistors] (video)
1961 Zuse 23 [transistors] (video)
1963 Timesharing (multiprocessing, multitasking) (video)
1964 IBM 360 (video)
1970 PDP 11 (video)
1974 Intel 8080 (video)
1977 Tandy TRS-80 (video)
1983 IBM PC XT (video)
1995 Dell Latitude, MS Windows 95, Internet, Mosaic Browser (video)
2007 Google 1 Million Servers, YouTube, Google Maps/Earth (video)
2011 TOP500 Supercomputers (video)

Here is a video of Zuse as a person:

* * *

Flying in Africa (Dornier Do 27)

2011-03-24T15:18:00.010Z

An interesting YouTube video the famous film of Bernhard Grzimek "Serengeti Shall Not Die" (German: Serengeti darf nicht sterben) is a 1959 German documentary film. It was written and directed by Bernhard Grzimek.

It was sad that his son, the cinematographer Michael Grzimek died on-location during the filming of the documentary. The film won the Academy Award for Best Documentary Feature in 1959.

On January 10 1959 the plane (Dornier Do 27) piloted by Michael collided with a vulture and he lost control over it.

A vulture

The crashed plane

Michael was killed in the crash. He was buried the same day on the top of the Ngorongoro Crater. Later the government of Tanzania erected a stone pyramid over his grave. Bernhard Grzimek was buried there after his death in 1987 as well.

Michael and Bernhard Grzimek

Pyramid of the father and son

To make the plane look natural to the animals it was painted with zebra stripes pattern.

The Grzimek's Dornier Do 27 can now be seen in Deutschen Technikmuseum Berlin.

Specifications (Do 27Q-5):

General characteristics
Crew: 1 or 2
Capacity: 4-6 passengers
Length: 9.60 m (31 ft 6 in)
Wingspan: 12 m (39 ft 5 in)
Height: 2.80 m (9 ft 2 in)
Wing area: 19.4 m² (208.7 ft²)
Empty weight: 1,073 kg (2,365 lb)
Max takeoff weight: 1,850 kg (4,080 lb)
Powerplant: 1× Lycoming GO-480-B1A6 6-cylinder piston engine, 201 kW (270 hp)
Performance
Never exceed speed: 333 km/h (180 kn, 207 mph)
Maximum speed: 232 km/h (125 kn, 144 mph)
Cruise speed: 211 km/h (114 kn, 131 mph)
Stall speed: 74 km/h (40 kn, 46 mph)
Range: 1,287 km (695 nmi, 800 mi)
Service ceiling: 3,290 m (10,800 ft)

* * *

Boeing 747-400 Autopilot

2011-01-10T00:10:00.001Z

An interesting lesson about 747 autopilot and how it is operated in different modes.

* * *

LEDs - The Most Efficient Modern Man Made Light Source (35%)

2010-12-26T23:13:00.008Z

They are now using LEDs everywhere and LEDs will replace most fluorescent lights in the future. Let's have a look what they can do.

BTW: Regardless of LED color, Cree advises users not to look directly at any LED lamp.

Here are a couple of videos.

Some LED safty factors:

"All light sources have the potential to be harmful to both the skin and the eyes through UV, blue light (410-480 nm) and IR emission. Independent photobiological testing of Cree visible light LED lamps has confrmed that the only health risk of visible light LED lamps signifcant enough to warrant advisory is viewing blue light with the eyes. LED lamps that emit blue light may be called multiple names, such as Blue, Royal Blue or Dental Blue. In addition, many white LED lamps, including Cree’s, are based on blue LED die and contain signifcant blue light content. Therefore, Cree has tested its Royal Blue, Blue and White LED lamps for eye safety.

Cree’s testing to date indicates that Royal Blue and Blue (450-485 nm dominant wavelength) LED lamps pose a higher eye safety hazard than White LED lamps. Other colors of LED lamps, such as Green or Red, do not pose a defned eye safety risk. Regardless of LED color, Cree advises users not to look directly at any LED lamp."

Cree® XLamp® XP Family LED

* * *

New Boeing 747-8

2010-12-22T17:13:00.003Z

New Boeing 747-8 properties shown in this video.

More interesting videos about the new Boeing in the following link:

http://www.boeing.com/videos/video.html?fr_story=fb12dd36c133ad4f3fb73d5195b3ab80b2a5fea4&fr_chl=92f816b0c0d4ca1c99f2d685e52e658cba0c9648

* * *

Cockpit Mock-ups

2010-12-18T19:37:00.015Z

Some links to wooden cockpit mock-ups:

Cockpit and Nose Mock-up

A wooden mock-up shell showing the electrical wiring of the Bombardier de Havilland Canada Dash 8 Q400 turboprop passenger plane.

http://www.flickr.com/photos/18378305@N00/4320337758/

70 percent P-39 cockpit and nosecone mock-up

http://www.eaa.org/experimenter/articles/2010-02_womb.asp

The museum's Lancaster cockpit mock-up was on hand at the fly-in.

http://www.bombercommandmuseum.ca/newsletter2004_2.html#index2004_2d

A wooden mock-up of Concorde was made at Filton in Bristol, 1963.

http://news.bbc.co.uk/2/hi/in_pictures/8492840.stm

Dornier Do-X Wooden Moch-up

"Dornier Do-X design work began in 1924 in Altenrhein, Switzerland and nearly a quarter million man-hours were expended over the next five years before full size wooden mockup of the aircraft was completed."

"A new feature was the division into three decks. The cockpit, the navigation and radio room and the machinery room were located on the upper deck, while the main deck with its luxurious furnishings provided seating for up to 66 passengers. The lower deck was used to store fuel and supplies. For the first time in the history of aviation, a one-to-one wooden mock-up of an aircraft was built. For the construction of the Do X, a special assembly hangar with a slipway had to be erected, the site selected being Altenrhein on the Swiss shore of Lake Constance."

* * *

Navigation Terminology

2010-12-17T19:51:00.005Z

After now using MNS (Master Navigator Software) for several years it is time to learn all those abbreviations used in the navigation terminology. Cross Track Error or XTE is the key word for the quality of guidance. If you can keep XTE at it's minimum it is proven that you made the shortest distance from point to point.

Picture: Cross Track Error (XTE)

Here is a typical MNS guidance screen.

Picture: MNS En Route Guidance Screen

XTE is shown on the right side blue window. At this moment we seem to be 898 meters left of the great circle between Nord and Npole (Nord and Npole are our waypoints) in this leg. When executing the route you should always keep XTE at it's minimum. The total leg distance is 920 km and it's true bearing is 0 degrees.

On the left side blue window you see several other parameters. Here they are explained:

WPT - Way point name
RTE - Route name
DST - Distance to way point or route end point
ETA - Estimated time of arrival to the way point or route end point
TTG - Time to go to the way point or route end point
VMC - Velocity made on course
CMG - Course made good
BRG - Bearing to the way point
LEG - Leg name
XTE - Cross track error (L/R = Left or right)
COG - Course over ground (Ground path direction)
HDG - Heading of the vehicle

Some more waypoint terminology in the following videos. MCDU stands for A320 Multifunction Control Display Unit.

* * *

Airbus A380 High Lift Devices

2010-12-03T18:13:00.018Z

An interesting video about A380 hi-lift devices. Notice that when using full flaps the small aileron becomes so inefficient that additional large span spoilers are needed. It is also interesting that the actual aileron is splitted to several parts and they seem to work sequentially: when one part is fully used the next part assists. The LAF (Load Alleviation Function) system must play a role here also.

Spoilers are sometimes called "lift dumpers". Spoilers that can be used asymmetrically are called spoilerons and are able to affect an aircraft's roll. For readers not familar with aircraft controls here is more basic information about it.

The flaps and slats are operated by long shafts and gear boxes from single motors located in the center of the fuselage as seen in the following picture. This is the noise heard in the videos.

SFCC stands for Slats & Flaps Control Computers.

Here is how the splitted aileron works and why it works as it does:

"The 380 has 3 ailerons per wing, an outer, mid, and inner, the inner aileron has an electrical back so the aircraft could be controlled even in the event of a total hydraulic failure.

For takeoff landing the ailerons deflect down a little, that is called the "Aileron Droop Function" (ADF), the objective of the ADF is to increase the high lift function performed by the slats and flaps. All the ailerons droop downwards (3 each side), when the flaps are extended. Ailerons and spoilers execute the roll function. Spoilers are needed at slow speed since ailerons only would be too unefficient for the roll function.

The ailerons also have another function called, "Load Alleviation Function" (LAF), the objective of the LAF is to reduce structure fatigue and static loads on the wing during manoeuvres and turbulence.Spoilers 6 to 8 and all the ailerons are involved in the LAF.

The LAF unloads the stresses on the wing by momentaraly deploying the flight spoilers and deflects ALL ailerons upward. The function is so fast that it is hardly noticable. I do not think that it makes the turbulance feel any worse though. The function seems to work very well.

These functions (apart from the electrical backup) are common on other Airbus types."

Some additional Airbus flight control documents (pdf format):

A380 Flight Controls Overview

Airbus flight control system

Airbus A330/A340 Flight Control System

Airbus Digital Electrical Flight Control System

* * *

CAN Networks

2010-11-21T20:02:00.008Z

Since Bosch introduced CAN bus in 1980's it has been utilized in several other than car environments. Marine electronics uses it and call it NMEA 2000. Airplanes use it and they will call it ARINC 825. Since it is so famous here is a small and very informative tutorial to NMEA 2000 which uses CAN.

West Marine NMEA 2000 Tutorial

Typical Isolated CAN Network Interface

***

Panasonic U1 Mobile PC

2010-09-05T18:29:00.003+01:00

There is a nice new mobile PC computer (running Windows) from Panasonic that is rugged and that is more flexible for several applications than a laptop. Check the following videos.

U1 Introduction

An Application that Opens Doors

U1 is also Airplane Approved

* * *

Airplane Parachutes

2010-07-31T11:30:00.013+01:00

BRS parachutes have saved about 250 lives to this day. One parachute for a 500 kg airplane costs about 4.500 $. The following video tells how it works.

BRS Parachute System

Here is one story about how the parachute saved four lives.

Technical Details

The rocket launch tube and the handles

The canister assembly

The parachute is attached to the airframe at three hard points. The harness and the parachute is packed into the canister and the rocket is installed next to it. The rocket and the canister are usually somewhere inside the fuselage. Here are some pictures about the installation.

Different types of harness terminations

BRS-1050 Canister Installation in Apollo Delta Jet Trike

* * *

High G Simulators

2010-07-18T07:55:00.027+01:00

Here is some information about high G simulators from USA. The Blue Angels tested the ATFS-400 Phoenix and their test video tells most of it. At some points it is a bit choppy but otherwise it is the best next to the real F-18C fighter aircraft.

Blue Angels Visit NASTAR Center

The most difficult region for any centrifuge type high G simulator must be the region around zero G. When flying it is easy to produce zero G (see the picture below).

Flying zero G

With a centrifuge the region between +1 and -1 G is impossible. As soon as the centrifuge turns the gondola upside down there will be -1 G without any smooth transition from +1 G. The only way to produce zero G for small time periods is to have such a gondola that can be dropped to a free fall. I am assuming that the gryphon (GL-6000) concept could address this issue by dropping the cockpit? But even with that it is only possible for small time periods (see the video for GL-6000 below).

GL-6000 Gryphon Concept Render

To make a long period zero G you would need a very high drop tower.

Somebody on Drop Zone

Of course you could put a centrifuge in a drop tower. But I don't know if that is done anywhere in that scale .

Drop Centrifuge Type High G Simulator

ATFS 400

"A revolutionary new technology called the Authentic Tactical Flight Simulator (Model ATFS 400) developed by Environmental Tectonics Corporation now offers pilots a ground-based simulator that provides more realistic tactical air combat experience at a much lower cost per event without the risk of airborne training. Deploying the new technology and transferring even a small fraction of airborne training to the ATFS 400 will save hundreds of millions of tax dollars, eliminate the ever-present risk of live combat maneuvering practice engagement - and save millions of gallons of scarce fuel."

ATFS-400 - Royal Malaysian Air Force

NASTAR Tactical Fighter Training Simulator

ATFS-400 Phoenix

GYROLAB GL-4000

"The GL-4000 is a high-fidelity, single seat interactive motion platform providing users with 360 degrees of continuous and simultaneous motion in 4 axes of motion (planetary, pitch, roll and yaw). Up to 6 Gs of motion stimuli are generated in the planetary axis. The GL-4000 can be used for flight training or research applications."

GL-4000

The same simulator is also used to train space flight.

NASTAR Launch featuring Buzz Aldrin, Anousheh Ansari, and Greg Olsen

* * *

How do you stop that?

2010-06-22T11:04:00.006+01:00

A funny video about a rollerblade man. The question is how do you stop that fast if you need to?

Grimsel Pass

Here seems to be an answer (at the end of the next video):

Palos Verdes

This looks also rather "hardheaded" but must be fun also.

* * *

Light Re-entry Space Suit or Device

2010-06-09T17:56:00.101+01:00

Or: How to Do a Re-entry?

The aerodynamic heating at the re-entry makes it difficult to produce a small and light weighted re-entry device. It is known that at some point if the weight compared to the structural volume of the re-entry configuration is low enough the re-entry temperatures will get lower. Also the selected path will affect to the heating.

It is possible to reject small objects from the space and rescue them. Corona was the first successful recovery of film from an orbiting satellite and the first mid-air recovery of an object returning from Earth orbit.

Fire proximity suits first appeared during the 1930s, and were originally made of asbestosfabric (hence also known as the asbestos suit). Today they are manufactured from vacuum-deposited aluminized materials that reflect the high radiant loads produced by the fire.

An old 3 part NASA study about the re-entry maximum heat is below. What is told to be important is the maximum surface temperature formula:

T^4 ~ sqrt( W / (CD*A*R))

This tells us that minimal weight (W) with maximal drag (CD), surface area (A) and surface radius (R) yield the minimium maximal surface temperature (T). The following videos have the whole story.

Part 1:
http://www.youtube.com/watch?v=XFDTq-sYtLA&feature=related

Part 2:
http://www.youtube.com/watch?v=UOgusbiWb-A&feature=related

Part 3:
http://www.youtube.com/watch?v=3Hr6PM5Xbk4&feature=related

Space Shuttle Re-entry

Angle of Attack

The following description about the physics of the space shuttle re-entry tells that the shuttle really uses lift to lower the descend speed and to lower the temperatures involved. The next question would be: Why the descend speed is still so high that special materials have to be used? Can't a device just keep descending so slow that it would take several rounds around the world to descend and that no special materials at all would be needed?

http://www.bbc.co.uk/dna/h2g2/A6381038

What is required to achieve that? Maybe the re-entry vehicle must fly very high in the atmosphere several rounds around the world until the speed is low enough and then dive in it. The main requirement would be not to dive too early and to be able to handle the plasma which at very high level does not yet have very much energy.

Next more about the shuttle re-entry. Here is a diagram which shows different parameters related to the shuttle re-entry:

STS-5 Re-entry Data

It is really shown that the shuttle drops very fast during the first 5 minutes from 120 km to 75 km where the peak heating (and most intense deceleration) also begins. Angle of attack drops from 40 degrees and the shuttle starts to fly. The energy levels above 75 km are not very high as the speed change is also very small. At an altitude of 85 km, the flight surfaces of the orbiter become usable when the air is dense enough.

So there is an usable flight region above 75 km at least until 85 km where a flying device could fly making turns and even generate lift. And this would be the region where the light re-entry device could be kept most of the time to loose it's excess speed and energy and finally just fly down to the earth. Of course it is another story how to do it.

The space shuttle for example is simply too heavy and does not generate lift enough to stay there at the angle of attack it uses at that point. It just passes through to denser air where the temperatures rise more rapidly. See the "peak heating region" in the previous graph. Actually it could stay there or even pounce back to the space if it used less angle of attack. That is not used since it is considered that it would just generate more heat to stay there longer. I am sure that at some point the heat would eventually start to drop but obviously the landing time would be too long then?

The General Electric MOOSE and the link "Early Reentry Vehicles" give some answers to these questions.

Blunt body entry vehicles

NACA made the counterintuitive discovery in 1951 that a blunt shape (high drag) made the most effective heat shield. Here is more about that.

Balloon Re-entry

The Rockwell Saver concept

The Rockwell Saver concept promised a compact, lightweight solution and allowed the possibility to modulate drag and re-entry loads during re-entry by changing the size of the balloon. It required new materials technology at it's introduction time for the nosecap and balloon material.

In 2002 Japan achieved a new record: an ultra-thin-film balloon named BU60-1 made of polyethylene film was launched from Sanriku Balloon Center at 6:35 on May 23, 2002. The balloon kept ascending slowly at a speed of 260 m/min and successfully reached the altitude of 53.0 km (174,000 ft), establishing a new world record for the first time in 30 years.

Balloon BU 60-1

http://www.isas.jaxa.jp/e/snews/2002/07_06.shtml

Other Ideas

Most of the re-entry ideas originate from the 1960's when the space boom was at its' hottest phase.

General Electric MOOSE

"MOOSE was perhaps the most celebrated bail-out from orbit system of the early 1960's. The suited astronaut would strap the MOOSE to his back, and jump out of the spacecraft or station into free space. Pulling a ripcord would fill an inflatable heat shield with polyurethane. The astronaut would use a small hand-held gas to orient himself for retro-fire, and then fire a solid rocket motor strapped to his chest to return to earth."

"General Electric conducted a number of technology proving tests. A heat shield was manufactured and folded. Test subjects were foamed into place with various formulae of polyurethane (it was found necessary to add a little castor oil to the formula to allow the pilot to extract himself from the foam). In a final test the test pilot jumped six meters from a bridge in Massachusetts and successfully survived water impact and floated downstream (a competitor claimed there was a little bit of a difference between 6 m and 500 km)."

There is a big list of different re-entry proposals in this link.

http://www.astronautix.com/craftfam/rescue.htm

More information:

Atmospheric Reentry

Heat Shields

Aerodynamic heating

Early Reentry Vehicles

Atmospheric Re-entry (pdf)

* * *

The Making of a Large Wooden Propeller

2010-05-25T00:07:00.004+01:00

"Footage from the early NACA era at NASA Langley Research Center. The NACA were unable to obtain contractors to complete the construction of the blades because of the unusual size and specifications that were required. These blades would fill the new tunnels the NACA were creating. The process is extremely interesting to watch as these modelmakers were taught how to make these large blades. Several men worked on a blade at one time making teamwork very important to the process."

Part 1:

http://www.youtube.com/watch?v=l9UbnJlhrHA&feature=related

Part 2:

http://www.youtube.com/watch?v=OR3e8waXuWk&feature=related

Part 3:

http://www.youtube.com/watch?v=WS-XqOsxBHY&feature=related

Here is some background music for that.. (open in another tab).

http://www.youtube.com/watch?v=GZbuA7r17uk&feature=PlayList&p=0FF7E914AABDD630&playnext_from=PL&index=0&playnext=1

* * *

The Lipo Powered Airplane

2010-03-22T06:08:00.010Z

In the near future (or today) it may be more efficient to put a small and simple electric motor and lipo (lithium polymer) batteries to an airplane than conventional fuel with a heavy internal combustion engine with reduction gears. Check the following video what can be done with a dedicated electric motor with lipo batteries.

Lipo battery powered paraglider.

Here are two links to LiPo battery guides:

http://exoaviation.webs.com/pdf_files/Lipo%20Battery%20Guide.pdf

http://exoaviation.webs.com/pdf_files/Lipo%20Battery%20Charging%20&%20Safety.pdf

An electric paraglider motor in England (Notice the small size of the motor and batteries).

Sonex has already tested this idea.

* * *

Bede BD-5 Transmission

2010-03-12T11:09:00.005Z

The Bede BD-5 airplane had a pusher propeller which was mounted in the aft fuselage.

Bede BD-5.

Before the final version the drive system changed several times after testing. Donald P. Hessenaur documented the whole story and it can be found in this link. Here are more details about the drive system.

The freewheel solved the vibration problems.

A typical freewheel clutch.

Honda or Hirth engine.

Drive system installed.

* * *

Airbus A400M Specifications

2010-01-09T15:18:00.021Z

According to Airbus Military the A400M is filling an operational AT gap. It gives more tactical capability than C-130 or C-160 and more payload/range than C-17, C-5, An-124 or IL-76/78. In England they know that the main wing is mostly made of carbon fiber. That is where the Airbus wing factory is located.

Airbus A400M capabilities: 30 tons 4500 km, 20 tons 6400 km. Ilyushin Il-76 can transport 40 tons to 5000 km.

Specifications

The cockpit looks good.

Airbus A400M Wikipedia page.

Download A400M Pocket Guide (pdf).

* * *

Airbus A400M Maiden Flight 11.12.2009

2009-12-12T01:02:00.009Z

Airbus A400M Maiden Flight Video

Link to the Airbus A400M site:

http://www.airbusmilitary.com/Home.aspx

* * *

"Retard, retard" (Is that an insult?)

2009-12-04T13:09:00.009Z

Is the autopilot insulting the pilots when an airplane lands? Press the play button below to listen the sound of an Airbus A320 during the round out and flare:

Here is an answer:

""French Insult?

Question:

Whenever I'm sitting in first class on an Airbus, I hear the computer call out the altitude just before landing. I also hear it say "Retard". What exactly does that mean? I thought it must be the signal to deploy spoilers and reverse thrust.

Answer:

No, it's nothing to do with the spoilers or reverse thrust. The word "retard" is a reminder to pilots to bring the thrust levers to idle during the landing maneuver, known as the "flare," just prior to touchdown. If the autothrottles are engaged, which they are most of the time on highly-automated aircraft such as the Airbus, the thrust will go to idle on its own just prior to touchdown on landing.

On Airbus planes, the thrust levers themselves don't move with the autothrottles engaged, so it’s a reminder for the pilot bring the thrust levers all the way back to idle to match the thrust setting of idle for landing. If the pilot ignores the directive, the thrust will still be at idle, however, regardless of the position of the thrust levers.

If the autothrottles aren’t on (they're left off sometimes for practice), then it’s telling the pilots to bring the thrust to idle by bringing the thrust levers back all the way. It’s basically the same directive as when the autothrottles are engaged, but in one case it’s a reminder that thrust is being reduced automatically, and in the second case it’s a reminder to the pilot to reduce the thrust manually.

Here's an interesting tidbit. I noticed during my eight years on the Airbus that the fact the throttles don't move when the autothrottles are engaged drives a lot of guys nuts, but, for whatever reason, the women I flew with didn't seem to mind. This held true for me as well. It didn't bug me that the thrust levers didn't move when the thrust was changing, but many of the guys I flew with said it just didn't seem right and they found it mildly disconcerting.

By the way, there is another theory that the word "retard' is said by the airplane to pilots as an insult by a French airplane to Americans who fly it, but it's conceivable our imaginations may be a tad too active. C'est la vie!""

Here is more about autoland procedures:

http://www.chipsplace.com/helpful/Airbus/CAT%20II.htm

(BTW: Do NOT click "Back to Table of Contents" on the bottom of that page since there is strange html code on those pages. What ever the linked page was ok.)

* * *

Autoland 2009 (CAT III B, Most Large Airports)

2009-12-01T02:45:00.024Z

CAT III B Autoland

Autolanding is categorised according to the amount of automation. The CAT III C is the highest with the following meaning.
"Category III C - A precision instrument approach and landing with no decision height and no runway visual range limitations. A Category III C system is capable of using an aircraft's autopilot to land the aircraft and can also provide guidance along the runway surface.

In each case a suitably equipped aircraft and appropriately qualified crew are required. For example, Cat IIIc requires a fail-operational system, along with a Landing Pilot (LP) who holds a Cat IIIc endorsement in their logbook, Cat I does not. A head-up display which allows the pilot to perform aircraft maneuvers rather than an automatic system is considered as fail-operational. Cat I relies only on altimeter indications for decision height, whereas Cat II and Cat III approaches use radar altimeter to determine decision height.

An ILS is required to shut down upon internal detection of a fault condition as mentioned in the monitoring section. With the increasing categories, ILS equipment is required to shut down faster since higher categories require shorter response times. For example, a Cat I localizer must shutdown within 10 seconds of detecting a fault, but a Cat III localizer must shut down in less than 2 seconds."

More info: http://en.wikipedia.org/wiki/Instrument_landing_system

Autoland Categories

"Autopilots in modern complex aircraft are three-axis and generally divide a flight into taxi, take-off, ascent, level, descent, approach and landing phases. Autopilots exist that automate all of these flight phases except the taxiing. An autopilot-controlled landing on a runway and controlling the aircraft on rollout (i.e. keeping it on the centre of the runway) is known as a CAT IIIb landing or Autoland, available on many major airports' runways today, especially at airports subject to adverse weather phenomena such as fog. Landing, rollout and taxi control to the aircraft parking position is known as CAT IIIc. This is not used to date but may be used in the future. An autopilot is often an integral component of a Flight Management System."

More info: http://en.wikipedia.org/wiki/Autopilot

Some more YouTube videos:

* * *

Autoland 1968

2009-11-27T00:40:00.003Z

GANDER TO LONDON - BOAC VC10 AUTOMATIC LANDING

A video about British BOAC VC10 Autoland System 1968.

The video tells that it is highly unlikely that anything could go wrong. The truth was that the autoland project was scrapped due to it's estimated reliability being too low. The actual story about that can be found in the following link.

http://www.vc10.net/Memories/radio_development.html

Here is part of the story duplicated. Chris Mitchell worked for BOAC/BA Engineering for 30 years and tells:

"A Cat 3 autoland system was designed by BAC for the VC10. This was a duplicate fully monitored system of Byzantine complexity. Remember this was before the digital age, it was all magnetic amplifiers and analogue computing. Effectively this meant that each function was done four times, and all had to work for the system to meet Cat 3 standards which of course they rarely did.

The Radio systems bore most of the blame at the monthly project meetings and as I was the sole wireless man at the meetings surrounded by twenty instrument and autopilot experts from BOAC and BAC I didn’t stand much of a chance. It was decided that the Radio Altimeters needed improving, not surprising really as they were made by STC to a design that must have been obsolete 20 years previously. The quote from STC for a modification package was horrendously expensive so I got lumbered to do it.

I replaced all the coax cable with a special low loss version with a silver plated foil screen that was almost impossible to work with. We must have scrapped more cable than we used. We matched all the mixer diodes by individual selection and redesigned the monitor system completely.

After about a year’s hard work the Radio Altimeters were working perfectly but the autoland system still did not perform. BAC then came up with a proposal for a package of modifications to all the other black boxes at a cost that made STC’s proposal seem small fry. By this time I felt a little more confident as I had proved the point with the Radio Altimeters and as I had some spare time I sat down at my desk and calculated the probability that all of the boxes would remain working for the four weeks required on average to certify an aircraft to Cat3 standard after a defect.

As I recall this worked out that on average a maximum of one aircraft in the fleet would be certified for half the time. I could not believe this result, so I rechecked the maths, re-read the books but could not get a better result. We had already spent millions on the system and were planning on spending several more. I could not believe that my sums were correct, but I wrote it up anyway and went thus armed to the next project meeting where the big mod package was planned to be agreed.

I dropped the bombshell at the start of the meeting by asking the BAC experts what their planned system reliability was. I got a few blank stares, they seemed to have experts there on everything except reliability, but it was agreed that they would show my workings to their specialists at Weybridge and find the errors.

Much to my surprise, the mod program decision was deferred. The next meeting they announced that my numbers were wrong, I had omitted to take into account the system wiring reliability so the situation was actually slightly worse than I predicted.

VC10 Autoland was promptly scrapped and work started on another mod program to save weight by removing all the surplus equipment. I never got any thanks for saving the corporation all those millions, possibly because I asked the Project Manager who had signed the contract; which had no guaranty that it would work or compensation if it didn’t. 'Me' he replied and walked away."

* * *

Rough Dimensioning with Fibre Composites

2009-11-11T15:29:00.011Z

There is a nice composite materials handbook, "R&G Handbuch Edition 06/2009, Composite Materials Handbook" (both in english and germany) available free on the network at the following address:

http://download.r-g.de/handbuch_edition_06_09.pdf

There starting page 80 you can find instructions how to estimate the airplane structures roughly:

Wing Spar Cutaway

"The simpliied example given shows how preliminary dimensions can be roughly calculated for fibre composite components. The values are based on material characteristics encountered in glider construction. Exact dimensioning may necessitate determining the material characteristics from case to case, which vary depending on the manufacturing method."

Basic Flight Mechanics Book

2009-11-02T18:22:00.005Z

There is a new book available that covers most of the math needed to do the flight mechanics calculations:

David G. Hull,

"Fundamentals of Airplane Flight Mechanics",

Springer-Verlag Berlin Heidelberg 2007

Here is a sample:

"Flight mechanics is the application of Newton’s laws (F=ma and M=Iα) to the study of vehicle trajectories (performance), stability, and aerodynamic control.

There are two basic problems in airplane ﬂight mechanics:

(1) given an airplane what are its performance, stability, and control characteristics? and

(2) given performance, stability, and control characteristics, what is the airplane?"

David G. Hull,

"Fundamentals of Airplane Flight Mechanics",

Springer-Verlag Berlin Heidelberg 2007

http://www.springer.com/engineering/mechanical+eng/book/978-3-540-46571-3

* * *