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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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