Do airplanes need gravity to fly?
Okay, so I understand Bernoulli's principle about generating lift and what not, but I am curious if any of that lift generation would matter if there was no gravity to oppose it. Suppose one was in a giant outer space airport with the pressure and air that of earth, and it began its takeoff roll, would the plane be controllable in the three dimensions? Would minimal engine power be required to fly it? What else can you tell me and derive from this hypothetical situation?
- Best Answer
It is an interesting question. The airplane could work and be stable. With a cambered wing, you'd have to operate the aircraft with a negative angle of attack (push the stick forward to get a nose-down attitude) to get zero lift. Of course, "down" in this case means with respect to the aircraft, not with respect to gravity! It would be better to use a symmetric wing section. Then it could fly straight with zero angle of attack. If you pull the stick back, then the aircraft would go to a positive angle of attack and would fly a loop. If you pushed the stick forward, then the nose would go down and you'd fly an outside loop.
The dihedral effect would not do you any good because there would be no gravity to make you start to sideslip if you rolled a little, so you'd have to control the ailerons to keep the roll angle straight.
You could not just roll to turn, but instead you would have to roll to a new angle and then pull up to fly a partial loop until you were pointed the way you wanted. Then you'd have to straighten out.
If you stepped on the rudder, it would cause the airplane to yaw. While it was yawing, one wing would be moving ahead and going slightly faster than the other wing. On a normal airplane with lift in gravity, this causes more lift on that wing, which causes a roll. But in this zero gravity situation, the wing would normally be at zero lift, so going faster would not cause a roll. But the sideslip angle would cause a sideforce on the fuselage and that would make you curve in a horizontal path. So you could turn just using the rudder. I guess that means you didn't have to roll to turn the way I said before.
Anyway, yes, the airplane would be controllable in all three dimensions (roll,pitch, yaw).
It would still need power to fly because there would still be drag from the air. But there would be much less induced drag (only when maneuvering). When flying straight, you'd only have profile drag. So it would require less power to fly.
To land, you could fly along a horizontal surface and then create some "downward" force using the wings at a small negative angle of attack so you would have a normal force to allow any kind of friction braking from the wheels. When you finally came to a stop, you'd be in free fall, so nothing would really hold you down. Maybe the propeller could be swivelled to push downward against the surface so you could get out with your magnetic boots and tie the airplane down to the tiedowns.
Very fun question.
- Anonymous3 years ago
No, but they'd need gravity to land.
- Anonymous3 years ago
They wouldn't need lift, if gravity did not exist.
If it didn't, there would be no need for aircraft at all. But then again, we could never have existed, because our world would not have existed. Gravity was essential for its formation.
Your "giant outer space airport" also, could never have been built, no- one to do it, and nothing to work with anyway!
In a perfect world they dont, but gravity creates an atmosphere providing the thrust they need, without gravity there would ve no thrust, but like i said in a perfect world if there was no gravity but the atmosphere remained, nooe they dont need gravity