why does lower air density result in lesser lift force?

Answer 1

The above answer is correct, but poorly written. Lower air density is just that, the molecules of air are farther apart. Thus a airfoil must move faster or change its camber to get an equal amount of lift that it would generate at a higher air density.

Answer 2

Okay, okay... most of the answers here are right in one way or another.

But the swimming pool analogy is... well, ehh.... let's try this.

Picture this - you put a bunch of little tiny beads (air molecules) into a very small container (air itself), practically filling it up. You can see that the beads don't have that much space between them, and chances are that if you opened the container and dropped an object in... say, a marble, the marble is going to stay up near the surface because there are enough beads under it to hold it up. Hence, high air density and lots of lift.

As the air density decreases, just imagine a few of the beads becoming more like balloons... eventually the marble just falls down to the bottom because it's too heavy for the balloons to support. Therefore, lesser lift.

I know, it's a funny analogy... but hopefully it somehow helps you understand not only the concept of lift and air density, but all that techno-babble, too!

Answer 3

Stick your hand out the window of a moving car. Change the angle of your hand relative to the wind by rotating it thumb up or thumb down. You are changing the airflow across the airfoil created by your hand. Any change in airspeed or angle of incidence (change in air flow), warmer temperatures or change in humidity (change in air density) will change the lift co-efficient either up (more lift) or down (less lift).

Answer 4

Answers 1 & 2 are OK, but try this:

The lift comes from the change in momentum of the air by virtue of the wing deflecting it downward. Momentum is m*v. For the same velocity, the mass is proportional to the density. So, with less density, you have less mass being deflected, less momentum exchanged and less lift......

Answer 5

I'm not sure, but think of it as swimming in a pool. The water can keep you buoyant. Now imagine a bunch of water bubbles where you are swimming. There will be more air than water, making the water less dense, and it will be hard for you to stay up. It's kind of the same concept.

Answer 6

U have fewer molecules going over the wing therefore the lift is decreased,If there is no turbulence (friction) U have nothing 2 push against-If air had no friction what do U think a hewey would do.

Answer 7

so the wings in "space" don't do a thing.

i.e, wings on a space-shuttle in "space" have absolutely no job. They are made only for landing purpose.