Algodoo

Yea, it can be very good for wing since you can generate any force and completely simulate aerodynamics. It's possible to add flaps, interceptors, engine force, engine reverse in single device. Great!
btw- did you try to glue circles instead of fix them? You don't need any trick with geomID then. Just get (once) and set glued "body" property. Look at scene response.

And I've simplify speed calculation just add "g" force for spawning circle.

Kilinich:
Is there any negative effects with gluing it?
Why doesn't it work if the scene gets changed?

Another thing I can do with this is make top view wheels that can handle any speed.

I prefere not to add in the gravity on the fall calculation(its not simpler btw), the reason is that the way it works now the spawned circles doesn't constantly pull whatever object its attached to downwards.
This gives a small negative effect in that it won't fall exactly as fast as other objects, but the advantage is that I can spawn heavier circles.

1) No problem with glue.
2) Body id changed, need to detect it via app.step
3) Depends on what you want to make - if we talking about RaUnit-alike stabilizer, adding gravity for spawning circles is exactly what you need to provide zero-affect on falling/moving. Why you need harder circles? Just add more angvel - it's unlimited.