If gravity pulls objects toward the earth's surface, how can birds/airplanes fly?

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.

Interesting question! Well, when you learn about aviation you see the diagram about how the airplane stabillizes in flight by balancing thrust and drag, lift and gravity. Without gravity, airplanes would at least look very different.

They'd need to generate negative as well as positive lift, and control them to climb or dive (you couldn't glide! You couldn't stall! How could you land?) Also balance is very important in an airplane, I mean balance of weight, left and right as well as fore and aft.

That wouldn't be important in a weightless situation. But you know a planet with no gravity would have no atmosphere anyway, right? All the atmosphere would just drift away!

So no air pressure, so no lift either way.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.