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Dec 12, 2009

Airbus A400M Maiden Flight 11.12.2009

Airbus A400M Maiden Flight Video

Link to the Airbus A400M site:

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Dec 4, 2009

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

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:

A320 50-30-20- Retard Retard sound bite

Here is an answer:

""French Insult?


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.


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:

(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.)

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Dec 1, 2009

Autoland 2009 (CAT III B, Most Large Airports)

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:

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:

Some more YouTube videos:

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Nov 27, 2009

Autoland 1968


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.

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."

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Nov 11, 2009

Rough Dimensioning with Fibre Composites

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:

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."

See also:

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Nov 2, 2009

Basic Flight Mechanics Book

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

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Jul 14, 2009

Aerial Photography

After doing some studies about  WW2 aerial photo shooting (spy cameras), it seems to be clear that most cameras  look very much the same. The focal length is usually under 1000 mm and you usually need 2 men to carry such a camera. Modern cameras are very much the same but the large film is mostly replaced by digital electronics. Some might have the ability to send the pictures directly and also have the possibility to take video.

There is an interesting history about American aerial photography here.

At the moment this list is not complete.

USA Camera Models

K-17 Camera 

K-24 Camera

K-7 A Camera World's Largest 1929

British Camera Models

F-24 Camera
F-52 Camera

German Camera Models

EK 16 Camera
Rb 50/18 Bomb rack Camera 
Rb 50/30 Camera
Rb 12.5/7x9 Camera

Russian Cameras

Unknown make and type
Maybe later than WW2
Focal length 1000 mm

Jun 23, 2009

Controllable Vortex Generator - M. Cambell

United States patent number 6427948 (2002) describes an interesting vortex generator that can be controlled by electric current. Check the following pictures and links for more details.

It could as well be some kind of a simple mechanical device that bends the fins when force applied.

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Jun 4, 2009

Barracuda - Wooden Beauty

I can not help putting some pictures and links to this beauty.

Picture: Barracuda, designed by RAF pilot, Geoff Siers

And here is a link how to get it.

Some more information.

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May 1, 2009

SPOT Messenger and Galileo GNSS

With the SPOT Satellite Messenger help is always within reach. Check the following video for more details.

Galileo GNSS (Global Navigation Satellite System) is now publicly-funded by EU and it's testing is advancing. The next video has more details.

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Apr 12, 2009

BMW Isetta

BMW Isetta was a small post ww2 car with some personal design features: the door opened forward.

Here are some pictures of it found in the Internet.

Mar 18, 2009

Moon Man Anatomy

It is clear that after few generations the future moon man will adopt to the lower moon gravity (1/6 of earth's gravity). Here is a picture of such a person compared to the earthling.

After few generations on the moon, it is very much possible that the moon man is not able to walk on the earth any more, since he needs more muscles and stronger bones to do that. Maybe the moon should be a place where people should only visit maximum few years at a time and then return to the earth. Moon would be a great place for tourists that seek extreme sports and exotic places.

Mar 12, 2009

Bird Strikes

The kinetic energy of the bird hitting an object is

E = 0.5*m*v^2

Let's see, speed is about 200 kts and the bird weight is 4 lbs. That is 103 m/s and 1.8 kg, so we get

E = 0.5*1.8*103*103 = 9550 J

Wow... that is some load for a plexiglas. There is "Plexiglas T3" (trade name) available, which is 22 times tougher than standard acrylic sheet. The following link seems to have some design information.

Let's do some additional estimations. If the impact energy is stopped so, that the plexiglas bends 0.2 m (20 cm) and since J = Nm and the energy goes from full to zero, we can now do a raw estimate:

E = 0.5*Fmax*s ->

Fmax = 2*E/s = 2*9550/0.2 = 95500 N ~ 9700 kg !!

Even the average force is about 5000 kg or 5 tons. A very good reason not to have a windshield angle too much with the horizon.

Very hard to say, how thick the plexiglas should be without testing, since the impact angle is also a very meaningfull factor.

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Mar 5, 2009

Sketching up an Airplane in 3D, Part 3

The Google Sketchup warehouse has some more airplane tutorials. To make rather accurate fuselage designs, first sketch them in 3-view (2D plans) and then make lofting 3D in SketchUp.

Links to some tutorials follow:

To build them, you have to anyway draw several work drawings from the "master" model. Afterwards it might be possible to join all those work drawings and models and make a more accurate 3D model.

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Mar 3, 2009

Sketching up an Airplane in 3D, Part 2

After doing some sketching with Google Sketchup 7 I find it wery handy to do 3D shapes.

To do more complex curves you need to load the spline library (Bezier Spline v 1.2) from the following link:

Download that and extract in the SketchUp Ruby plugins folder:

C:\Program Files\Google\Google SketchUp 7\Plugins

The following tutorials are also handy.

Normal 3D CAD packages usually can also handle creation of complex shapes.

The Ruby scripting language offers a method to parameterize some routine procedures.

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Mar 1, 2009

Sketching up an Airplane in 3D, Part 1

Google is promoting their new sketchup tool, Google SketchUp. I just learned that to make a fast sketch of an airplane is easiest by loading it up from the library. But it seems also to have lot of nice 3D tools to really make some sketching. I have to do some testing. Meanwhile you might want to check the program too? Links are below.

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Feb 22, 2009

Wing Design Tools

Some new wing design tools are on my new site availabe online.

Go to -> ExoAviation

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Feb 19, 2009

Nancy-Bird Walton - Quantas new A380

Quantas new A380 got it's name from Nancy-Bird Walton, the Australian aviation pioneer.

See the story ->

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Feb 16, 2009

"Rocket Rutan"

What ever, there seems to be one advantage of a missing tail. You can't mess it with the rocket flare.

A bit more fuel and you would touch the space.

Well, that seems to be only some minor design detail... ;)

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Feb 15, 2009

Airplane Lightning Protection

Now this seems to be a difficult question. Aircraft protection is different from car protection since there are several electrical systems that have to work before, during and after lighting.

Here are some ideas:

1. Make sure your aircraft forms a Faraday cage

In aircrafts as in cars the conducting surface is the most important protection for inside matters (people and systems). If the airfraft is made of glass fiber for example and does not have any natural conductive surface, then such a conductive layer (or arrangement) is made.

Make sure that the layer is able to conduct the currents in a lightning. For example a copper wire having a diameter of 10 mm is able to conduct most lightnings without damages.

2. Make sure that nothing important is outside that cage

This is important. If you have for example some aircraft light in a plastic holder on the wing tip, it will be an invitation for the lightning to come inside the plane and destroy something. In such a case wrap the plastic holder around a copper cable and connect that to the airplane surface (to the faraday cage). Try to arrange the internal conductve parts so that there is always some surface grounded parts in front of the part that will conduct the lightning to the surface away from the lamp holder and internal wires.

3. Do not ground anything to the surface (Faraday cage)

In cars it is common to ground everything to the vehicle steel frame. Don't do that in airplanes. Opposite to that keep the parts and wires at some distant from the faraday cage as seen in the video above and the picture below. The cage works but only if the parts are not too close to it.

Picture: Keep distance to the surface (which will conduct the huge currents of the lightnings)

4. Groundings

No groundings! How to arrange the groundings if one cannot be avoided. Inside the faraday cage the best is to have a single ground point that is NOT connected anywhere to the cage as in this video.

The person keeps his hand on a bar that is no conductive. This way only the shoe bottoms are grounded. Make sure there is never a ground loop anywhere. If an ground loop exists then the lighting might choose that way and it will put a huge voltage into that system destroying something.

5. Use transorbs everywhere

If the system is 12V DC battery, then use for example 18 V transorbs everywhere to protect the circuits. Remember that if you have a long wires to some part then both ends and maybe even somewhere between needs to be protected.

6. Shielded wires

Shielding does not help if the faraday cage is not working. Why? Since the shield will be the lightning conductor and the shielded system is mostly destroyed anyway if the lightning hits the shield. The shield helps to give more protection if the surface faraday cage is working and keeps the lightning outside the internal systems. Better to conduct it away (see section 2.)

7. Avoid lightnings and surges

Try to avoid thunderstorms and lightnings. The best surge is a surge that never happend.

Notice: The windows do have conductive layers so that the cage is complete.

Here is a small article about lightning protection in a composite airplane.

NASA made some airborne lightning research 1980-1986. Here is a video about those tests:

At 4:42 notice how it strikes inside the cockpit to the pilot (or looks like so).

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Feb 11, 2009

Some Wings

Picture: DC-9 wing

Picture: Boeing 767 Wing

Boeing 767 wing is a nice wing design full of details. First of all the whole leading edge is provided with slats. Slats will delay the stall on all configurations and they increase the wing maximum lift. Wing tips have normal ailerons and the wing has a twist that makes the tip stall latest. That ensures full control even at stall.

Wing inboard section is filled with Fowler flaps. Above flaps there are rows of spoilers. Plane is controlled with ailerons and spoilers. Ailerons are not enough at low speeds so the spoilers are also used. Spoilers function also as air brakes.

Wing inner section (the box spar) is filled with fuel. The box spar also provides the structural strength of the wing.

The following YouTupe video clearly shows how a Boeing 747 uses all spoilers at one side when landing, the tip aileron is totally too uneffective at that situation.

See time 0:07 and forward.

Boeing 767 Inboard Ailerons

Boeing 767 has also an inboard "normal" aileron, which is visible in the next YouTube video.

The famous DC-9 wing (no wing engines) which can produce CLmax = 3.0

notice very clean and simple design.

Link to Raymer's software pages

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Feb 8, 2009

Faileron - New Control Surface? or Eleron?

After reading about the elevon, flaperon and taileron I invented a new control surface: FAILERON

Sorry to say I don't know yet how it looks like... :D


That was actually a joke, but after thinking a while the spoiler aileron might also be called faileron or maybe saileron would be a better word?

There is a new patent about electronic (?!) aileron (eleron?) which is very interesting, US paten number 7,028,954 by Professor Van Dam year 2006.

Is this "eleron"?

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Best wing - least wing, least drag

Birds know that the best wing is the least wing. If there is no need for lift, it is best to get rid of most of the wing and just dive. The shape of the bird body (fuselage) gives the least drag and the wing is only used to give lift and control.

Aeronautical Calculators etc.

Some links to online calculators.

To calculate Reynolds numbers and similar values at any altitude:

To check the atmosphere model at any altitude:

Some other links:

NOTE: I have not tested all of them, there may be bugs.

Feb 7, 2009

Which Wing

Pictures: Ice build-up on the leading edge of a wing.

Pictures: Leading edge slats and trailing edge flaps (single and double slotted).

Which wing is the most optimal? Let's say I have to have fixed landing speed for various reasons (FAR, JAR, etc.). We set the landing speed to 61 knts for example.

Let's also say that I have the trailing edge flaps to lower landing speed (let's choose double slotted for maximum lift). In most airfoils the trailing edge is anyway turbulent, so the flap hinge line does not add any cruise drag.

Now the question is: Do I have any benefit of the NLF airfoil without leading edgen devices when I could also have the leading edge slats with not so laminar airfoil? Obviously the leading edge device destroys the flow there and I have a none laminar case.

1) With the more turbulent airfoil I get smaller wing (A1) and the L.E. device still lets me land at the desired speed (61 kts).

2) With the NLF airfoil I can not use L.E. devices to keep the laminar flow there, so I have to have a larger wing (A2) to keep the landing speed the same (61 kts).

So the question is now: Is the cruise drag for the wing 1 with the area A1 less or more than for the wing 2.

Using the wing area calculator in the next link:

I get the following results for some small airplane (same weight 4750 lbs) and both have the same landing speed (61 kts):

1) Leading Edge Slats, A1 = 126 ft^2

2) No Leading Edge Devices, A2 = 152 ft^2

I save 25 ft^2 if I use L.E. Slats. Is that smaller area enough to win the benefit of the NLF airfoil at cruise? Maybe sombody has allready done this calculation somewhere for some configuration. I have to investigate (or do it my self).

Additional details are that the laminar flow can be hard to keep if the wing is flying in snow, rain, etc. and that the L.E. device could be used to crack the L.E. ice. Other point is that the L.E. device adds some cost, weight and complexity.

I will return to this question later (with an answer)... or send me one!

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