Quote:
Originally Posted by sjastro
The question is whether birds and insects can fly in parabolic pathways in a zero g environment. My gut feeling is no. The descent requires the bird or insect to perform work instead of gravity to land.
If this is not possible the simplified pathway is an angled straight line, a one way trip to oblivion or a really bad headache. 
Regards
Steven |
No Steven, the question was actually this, "What would the dynamics of a bird in flight be like if there was air, but no gravity? How would the aerodynamics of lift, drag and propulsion change for a feathered bird?"
What I've been trying to describe, is what type of flight dynamics would be needed for flight in a zero G environment, then asking what type of bird might have the best chance of doing it. I have not entered into whether a bird is taking-off or landing as yet because I feel we must determine if normal flight is even possible first (the basics); before tackling more complex issues.
I agree with you that it would more than likely be impossible for birds to do so however, if there was a species that could do it, what species would it be. But first of all we must know what type of dynamics is required for basic straight and level first, then turns, and then we can bring our attention to ascent and descent (two meaningless words in zero G BTW).
You wrote, "The flight paths of birds and insects are not horizontal straight lines". I agree, lift must balance the field of acceleration, that's why stated that a symmetrical aerofoil would be needed as a cambered wing would generate lift unnecessarily as gravitation is not a factor. A symmetrical aerofoil would only come into play when a turn is initiated (angle of attack to generate lift).
The subject of landing and take-off is a different issue to sustained flight and wasn't the original question however, I responded by saying that landing on the ground - the floor - would be no different than landing into a wall, in that there is no up or down. That would also apply to landing on the ceiling.
For an aircraft, straight and level flight is indeed possible in zero G and best achieved by using a symmetrical aerofoil (no lift generated), good control surface area, minimal wing tip/tail mass, the ability to apply aileron force against engine torque (prop). Every control throw would require an equal and opposite throw to counteract the input. If you want an example, look no further than an aircraft in a parabolic free-fall which simulates a zero G environment..it's simply pitching the nose over at the same rate as the field of acceleration. Can a bird fly a parabolic free-fall trajectory with it's wings open, you bet, Hawks do it all the time.
Now is it possible for a bird to make directional changes while in a parabolic free-fall? Of course.
Can a bird take-off in zero G. Yes. If it's holding onto something, beats it's wings and lets go, that's a take-off...and it can do this in any direction as all directions are the same.
Can a bird land in zero G. No, it can only collide, whether it be the floor, wall or ceiling.
The single biggest issue would be that a bird would not be able to understand what is going on, so it would assume that the mysterious force of gravity was ever-present and make mistakes...but can it learn to compensate?!
Classic, love it.
