Some guys on the chevelle board are confused. There are thirteen pages on this thread regarding this "PHYSICS QUESTION"! OMFG THIS funny! ou:
Flight can ONLY take place when air moving over the wings of the plane create enough lift to carry the weight of the craft. Air MUST be moving over the wings! This causes an inverse negative and positive relationship over and under the wings, resulting in lift. In the Chevelle scenario the plane sits still, the wheels spin and no air is moving over the wings. Flight can not take place in this scenario.
Well, not to stir it up here. But a plane with a propeller might (Maybe) while a jet would not. My thinking is this: a propeller driven plane would be passsing air over the wings so it may be possible. Unlikely that the propeller will generate enough wind but might be possible. A jet plane, with its engines under wing isn't passing air over the wing so it won't fly no chance at all.
its thought provoking seems like a fun enough discussion,like some of the trivial stuff we babble about on here...it makes you use your noodle,and what I come up with is,if there is no airflow across the surfaces of the wing,there cant be any lift. i'm not a genius ,but thats just what i come up with. ok,so Maybe the chevelle guys are easily amused,but i have plenty in common with em...fish
The plane would take off fine. We all understand that forward movement creates airflow over the wing generating lift. So if the plane moves forward it will take off. We also understand that the engines use the air to move the plane not the tires. The treadmill does not stop the plane from moving forward it just makes the wheels spin faster. Without something to hold the plane back the engines will move it forward. The treadmill can spin as fast as it would like, it can't hold the plane stationary. If the plane can move forward it generates lift and takes off. The direction or speed of the treadmill has almost no influence once the plane is moving. The only impact is the friction in the wheel bearings which is negligible compared to the strength of the engines. John
how bout if a plane was standing still and there was a big fan in front of it? could it lift of the ground and fly away? pete
Actually there is a little misinformation here. There are two forces that allow a plane to take off. One is the often mentioned Bernoulli (sp?) effect caused by the air moving faster over the longer curved upper portion of the wing. This effect is not sufficient to lift the plane off of the ground. The second part is the angle of attack the wing takes. As the wing is angled up the lower surface is exposed to oncoming air and deflects it downward. This deflection then brings into effect the laws of motion. The downward deflection creates an opposite and equal reaction upward. This effect provides the majority of the lift need for a plane to take off.
Well, it could lift off the ground, but once it was out of the wind, it'd come back down. Hard, I'd imagine. Ever see pictures of an airport after a tornado or windstorm? That's the main reason they tie small aircraft down, so that high winds don't blow them around. But 73Centurion (John) is right, the treadmill would only spin the tires faster, and the airplane would take off. Unless one of the tires blew, then you'd have a gawd-awful mess all over your nice new giant treadmill. :laugh:
Got to think of this in relativity, the motion of the aircraft in relation to the air. If the conveyor belt is moving at the same speed of the wheels, the aircraft is then stationary in respect to the air. No airflow, no lift. A wing creates lift by creating a localized low pressure area over the top of the wing since when air changes velocity it must either change pressure or temperature. You get both but pressure is by far the prevailing result. The wing is then sucked into the low pressure area because it has less pressure on the top than the bottom, or if you flipped it over you get downforce like on a dragster. Angle of attack alters the relative path lengths effectively increasing the wings camber (measure of curveture) thereby creating more lift. This is caused by the air piling up under the wing creating higher pressures and the airflow seperating from the wing on the top creating an even lower pressure area. However this generally doesn't give you your resultant force completely in lift direction so you not only get more lift bt you get much more drag with a vector component in the drag direction and lift and drag are proportional regardless of thier directions. Simply said, no motion relative to the air, no lift.
the wheels are not driven by the plane. The wheels are drivin by the fricion of the plane rolling over the pavement/belt. the engine thrust is pushing the plane forward, not rotating he wheels. so the plane to take off would be doing about 300 mph and the wheels would be spining the equivelent of 2 times that amount. now are we basing this off of the front or rear wheels? cause as soon as the front wheels left the belt they would slow down causing the belt to slow down. our cars on the other hand woulden't go anywhere because the thrust comes from the wheels. -nate
I've been having fun with that one on Turbobuick.com all week. :Comp: I had fun stirring up people with the won't fly side of the debate. :rant: It looked like it needed some help. Some people get a little frustrated when you challenge their ideas and some aren't willing to look at different perspectives. Maybe some people thought that about my posts too p It was lots of fun. Oh yeah, I haven't read their thread but as soon as the plane began to move forward through the air, the conveyor would not slow it down, the wheels would only roll faster. Don't confuse wheel rotation with actual speed. The plane is not pushing against the conveyor to go forward, it's pushing against the air. Of course you can come up with an infinite number of scenarios that include unusual conditions (lots of fun p ), but using what we all recognize as a normal conveyor and normal airplane, it would fly. I was really surprised that no one brought up the "swallow analogy" over there. It seems so fitting to me.
