Peter_Pan Posted December 30, 2006 Share Posted December 30, 2006 A plane is on a conveyer belt which is turning in the opposite direction to way the plane is pointing. The belt can turn at any speed and we have indestructible tyres and bearings on the plane, could the conveyer belt stop the plane from taking off? I read this on another forum first and have been discussing it for ages so I have posted it here for you lot to have a go. Will it take off? Link to comment Share on other sites More sharing options...
YT2095 Posted December 30, 2006 Share Posted December 30, 2006 no it won`t, the wings need to move through the air to gain lift. Link to comment Share on other sites More sharing options...
Peter_Pan Posted December 30, 2006 Author Share Posted December 30, 2006 That was my answer but other where saying that the plane would just travel down the conveyer belt just as it would down a runway the conveyer belt would have no impact on the plane as the wheels just roll and are not powered. Link to comment Share on other sites More sharing options...
insane_alien Posted December 30, 2006 Share Posted December 30, 2006 yeah the plane would just roll along to takeoff speeds an then go up, this assumes the friction from the wheels is low enough to allow this to happen. Link to comment Share on other sites More sharing options...
YT2095 Posted December 30, 2006 Share Posted December 30, 2006 that would only work without Friction, and since there`s no lift taking place, friction will be ever present. don`t think for a second that a plane weighs Nothing! you need a good 80 knots of air over wings before you`ll get the needed lift. and if your ASI says 0, you`re going Nowhere Link to comment Share on other sites More sharing options...
insane_alien Posted December 30, 2006 Share Posted December 30, 2006 yes i know there will be friction but if its low enough to allow the planes air speed to rise to its takeoff (air)speed then the plane will be able to lift off. this means the wheels would be spinning at the conveyor speed plus the takeoff speed. if for instance, you upgraded the wheels on a 747 and sat it on a conveyor belt going 100mph the other way it would still be able to take off. Link to comment Share on other sites More sharing options...
YT2095 Posted December 30, 2006 Share Posted December 30, 2006 don`t confuse AS with GS, it`s a great way to get yourself killed! what Would happen (and you still need a runway!) is that when the props RMP got to a speed sufficient overcome the frictional forces, you`de have more pull on the Air than the ground (like cork screwing through air), at this point you plane would ignore the conveyor and move forwards anyway, until it got enough wing air for lift (about 80 knots AS). oh and you`de over tax your wheel bearings a little too seriously it`s air over wings that counts, nothing else here I`ll go one Further, give a good 80 knot head wind, and the plane will take of even if GS Stationary Link to comment Share on other sites More sharing options...
insane_alien Posted December 30, 2006 Share Posted December 30, 2006 i know the difference between airspeed and ground speed. its theoretically possible but nobody is going to build a conveyor belt long enough to launch a plane off of so its not practical. Link to comment Share on other sites More sharing options...
YT2095 Posted December 30, 2006 Share Posted December 30, 2006 i know the difference between airspeed and ground speed. its theoretically possible but nobody is going to build a conveyor belt long enough to launch a plane off of so its not practical. whut? Link to comment Share on other sites More sharing options...
Peter_Pan Posted December 30, 2006 Author Share Posted December 30, 2006 I think both of you are correct if you had a conveyer belt which was as long as a runway and the conveyer belt could only run up to 100mph the plane could still take off. All it would need to do is to overcome the added drag from the wheels. But if the conveyer belt could spin at any speed as long as the drag caused by the belt on the wheels equalled the thrust of the engine then the plane would go nowhere and wouldn’t take off. Link to comment Share on other sites More sharing options...
Cap'n Refsmmat Posted December 30, 2006 Share Posted December 30, 2006 If the wheels on the plane are capable of handling speeds twice normal takeoff speed, then the plane will take off. Link to comment Share on other sites More sharing options...
YT2095 Posted December 30, 2006 Share Posted December 30, 2006 But if the conveyer belt could spin at any speed as long as the drag caused by the belt on the wheels equalled the thrust of the engine then the plane would go nowhere and wouldn’t take off. Correct Link to comment Share on other sites More sharing options...
woelen Posted December 30, 2006 Share Posted December 30, 2006 That was my answer but other where saying that the plane would just travel down the conveyer belt just as it would down a runway the conveyer belt would have no impact on the plane as the wheels just roll and are not powered. Yep, this is also what I would say. Suppose the plain is standing still on the belt and the belt starts moving. Then the plain will not move together with the belt, the wheels will rotate and the plain will remain on its place, fixed, relative to earth. When the plain starts its engines, then it moves just as if it is on a normal air-strip. The only difference is that the rotational speed of the wheels is different. Of course, if there is friction in the wheels, then things will be different. Then the plain will follow the belt and then for each force, applied by the plane's engine, there will be a velocity, such that the engine's force is neutralized. Link to comment Share on other sites More sharing options...
Cap'n Refsmmat Posted December 30, 2006 Share Posted December 30, 2006 There are military aircraft with sufficient thrust to take off even with flat tires, so I suppose they could manage a conveyor belt with no problem. Link to comment Share on other sites More sharing options...
YT2095 Posted December 30, 2006 Share Posted December 30, 2006 indeed, as long the AS is correct for the craft, it`ll fly regardless GS has no relevance at all (else we`de never be able to fold up the landing gear as "useless now"). lets put it This way, if the conveyor thing would work, it would be used on aircraft carriers to shorten the take off distance or for UAVs, in fact the opposite is true, catapults are used to propel the craft forwards through the air to help give it head start. Link to comment Share on other sites More sharing options...
padren Posted December 31, 2006 Share Posted December 31, 2006 A plane is on a conveyer belt which is turning in the opposite direction to way the plane is pointing. The belt can turn at any speed and we have indestructible tyres and bearings on the plane, could the conveyer belt stop the plane from taking off? I read this on another forum first and have been discussing it for ages so I have posted it here for you lot to have a go. Will it take off? Technically, you could theorize that since wheels slow the plane due to resistance, and that since the resistance increases with how fast the wheels spin, and that you had the ability to turn up the speed of the conveyer to a point that the resistance caused enough counter force to overcome the forward force of the plane's engine, then the conveyer would stop the plane from taking off. The technical requirements for enacting this method would be insane of course, and if there was an 80 knot headwind it would take off anyway. Old discussion on this forum about this topic here Link to comment Share on other sites More sharing options...
Bluenoise Posted December 31, 2006 Share Posted December 31, 2006 It is not possible. A plane is huge and even the biggest conveyor belt would fit inbetween the wheels of a plane!!! It's a trick question!!! run for the hills!!!! Link to comment Share on other sites More sharing options...
ydoaPs Posted January 4, 2007 Share Posted January 4, 2007 It is not possible. A plane is huge and even the biggest conveyor belt would fit inbetween the wheels of a plane!!!It's a trick question!!! run for the hills!!!! I've seen plenty of planes that could fit on a conveyor belt. Link to comment Share on other sites More sharing options...
weknowthewor Posted January 7, 2007 Share Posted January 7, 2007 Lets try another method to takeoff a plane by air engine... Link to comment Share on other sites More sharing options...
John Cuthber Posted January 8, 2007 Share Posted January 8, 2007 A couple of thoughts. 1 A plane flying in the right direction (heading into the sunrise I think) on the equator is, in effect, on a conveyor belt travelling at about 1000MPH (this conveyor is normally called the earth). This wouldn't make any real difference to its abillity to take off because the air is being dragged along by the earth. Any conveyor that could run under a plane that was trying to take off would drag an enormous amount of air with it. This would create at least some lift. Once the plane starts to rise the friction is reduced. If you raise the belt speed in order to try to compensate for the reduced frictional drag then you will incerase the amount of air dragged over the wings and create more lift. I think that the plane takes off but I wouldn't like to pay for the conveyor or the fuel to run it. 2 Anyone got a vertical take-off plane? Link to comment Share on other sites More sharing options...
TriggerGrinn Posted January 8, 2007 Share Posted January 8, 2007 Float plains take off in water.. a conveyor belt simply would be a version of this situation. Forget the ground, the plane will fly when there is significant velocity between the air and the wings. Link to comment Share on other sites More sharing options...
Peter_Pan Posted January 9, 2007 Author Share Posted January 9, 2007 Float plains take off in water.. a conveyor belt simply would be a version of this situation. Forget the ground, the plane will fly when there is significant velocity between the air and the wings. Not really it would be more like a float plane trying to take off in a fast flowing river going up stream. If the river was flowing to fast the plane would not be able to pickup enough speed to take off. Link to comment Share on other sites More sharing options...
Rocket Man Posted January 10, 2007 Share Posted January 10, 2007 take a plane with a really low stall speed, and land it in a stiff head wind. i've heard of military pilots off-loading troops without touching the ground. the only factor that makes this different to a standard takeoff is excess drag. more throttle isn't difficult to come by, very very few aircraft need full throttle to takeoff. Link to comment Share on other sites More sharing options...
Klaynos Posted January 10, 2007 Share Posted January 10, 2007 Rocket Man: There was a German aircraft in WWII, the Storch, which has an amazingly low stall speed (under 25mph) on even quite calm days I've seen it land and it looks likes it's hovering allot of the time... Link to comment Share on other sites More sharing options...
wilgory Posted February 11, 2007 Share Posted February 11, 2007 HI, Having attended a college of aeronautics I can tell you there are 2 factors needed for flight. Not float but to take off. First, lift must overcome weight, the airflow over the wing needs to be suffient to produce enough lift. Second, thrust must overcome drag. The plane needs to be propelled forward. Since the plane is allowed to be powered by an engine, prop or jet doesn't matter. When enough force is applied by the engine to do these two things the plane will take off(fly). I hope this helps. Wilgory Link to comment Share on other sites More sharing options...
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