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No, they were not already moving quite fast when dropped. The X1 was dropped from a B-29...which what, has a speed of 200mph. Once its dropped, its forward speed decelerates rapidly because gravity is bringing its forward inertia down.

So yes, it's not exactly the same...but it's the best example I can think of of how the plane's initial forward movement is not effecting the lift of the wings. The problem with this question is the hypothetical conditions....so if we want to debate X-planes, that would be more worthwhile I think

My take on this. If the plane can move forward at a sufficient rate to have enough air flowing over/under the wings it will take off. That part should be pretty clear.

Thinking about the problem in reverse helped me to understand it.

If plane came into land on an aircraft carrier that had a conveyer belt assembly running the length of the deck and it was set to match the plane's landing speed, in the reverse direction, would the plane come to a dead halt as soon as the wheels hit the belt? No.

If you stopped the belt instantly, would the plane come to a halt? No (assuming no wheel braking).

If you started the belt in the direction of the plane's travel, would the plane speed up? No.

None of these changes to the speed or rotation direction of the wheel has impacted significantly on the speed on the plane.

So, my answer is that the plane will take off because regardless of the speed of the conveyer belt and the wheels, the thrust of the engine pushing on the air behind the plane will allow the plane to travel in a forward direction at a sufficient rate to enable lift.

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I'm thinking along these lines more and more. If we consider that the belt and wheels negate one another, then the forward thrusters are free to propel the plane forward and the ground mechanisms become irrelevant.

In other words, provided the conveyor was as long as a typical runway, the plane would traverse the distance just as if it were on a static strip of tarmac and therefore, would take off without a problem (provided the wheels didn't explode from the heat/friction).

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What makes this a confusing hypothetical (and one that would need clarification) is if the conveyor belt is always keeping the same reverse direction as the plane's forward inertia (not the wheel's rmps). The weight of the airplane and the wheel's tires are keeping the airplane down and in contact with the conveyor belt. Lets say you are sitting in a seat with wheels on this hypothetical conveyor belt. If you put a propeller on its back and have some magical way to keep the speed of the conveyor belt exactly in relation to the forward inertia as the propelled seat, will it go forward? No: the conveyor belt is canceling out the forward inertia of the propeller (and the other forces of gravity and friction are keeping their forces connected and keeping seat stationary).

With fordgtlover's example, a plane landing on a conveyor belt already has forward inertia. So it would act independently of the conveyor belt until gravity and friction with brakes eliminates its forward inertia for the conveyor belt's direction. Once the plane stops its forward motion, it would follow the direction of the belt because of friction with gravity. If the plane is starting its engines and producing forward thrust on this conveyor belt, the belt will meet and cancel any forward movement of the the plane afterwards (as they are now part of the same system).

Anyway...ponderous scientific thoughts, and why this question just makes your brain go round and round because of the different conditions

To end it, I'll just say that yes the plane takes off.....because it's an Osprey that has variable propellers go up and are not parallel to the belt's inertia

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And I'll say again that a solution like that would be a drity trick!

Anyone ruled out a Space Shuttle yet?

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No, this isn't the right way to look at it. You're comparing the speed of the conveyor belt to the force exerted by the thrust of the engines. You need to compare the relevant forces acting on the plane:

1. Force generated from the thrust of the engine, and

2. Friction generated from the spinning of the conveyor under the wheels.

It doesn't matter how fast the wheels or the conveyor belt spins. What matters is whether the force generated from the friction caused by that spinning is equal to the force generated by the engine. As long as the force of the thrust generated by the engine is greater than the force of the friction from the wheels/conveyor, the plane will move forward, and if it can move forward, presumably it can take off.

Think of the example that someone mentioned above about the roller blades on the treadmill: let's say you're holding onto a rope on the treadmill and that you are therefore at equilibrium (i.e., the wheels of your skates are moving at the same rate as the treadmill, and you are standing still compared an observer who is not on the treadmill). Now someone pushes you in the back. Will you move forward? Yes. The thrust of the plane's engine is the same push in the back, and so the plane will move forward.

Hey Folks,

I am a Pilot. I owned a Plane. I am an Engineer.

The plane would take off very, very nearly as if it was on regular old pavement.

Here's why: Looking at any plane, it is just the old Action/Reaction physics. The motor, of whatever power/design, provides thrust. The reaction is to push the plane forward. The plane's movement is decoupled from WHATEVER the supporting groundplane does, (in fore/aft direction) by action of the wheels and bearings.

If by use of unobtanium, and FM (F*kin Magic), the conveyer belt has a zero inertia, a capable regulator, and is capable of infinite speed, and infinite acceleration rates, it <Might> have a chance to keep the plane in place till the wheels/tires explode from rotational forces, but after that, the plane will accelerate unimpeded, and fly as normal. The interval between release of brakes on the plane to explosive destruction of the tires would be a matter of an infinitesimal instant, cause the plane WILL move forward.

My Puny old 1967 Cessna 182 would just drag the locked wheels and tires and go till liftoff, if there was the least little wet/oil/grease on the (ordinary) runway - only if the runway was totally clean and dry could it stay put against full throttle (Light on fuel, with just me onboard).

Just for fun, I have played in the opposite situation: 45 MPH winds, right on runway heading...then, I could take off STRAIGHT UP - no ground roll. Land the same way, no forward movement, just come straight down, and touch down with Zero ground roll. Taxiing is really tricky in those conditions - if you turn crosswind, you have to use a LOT of throttle and brakes to keep going.

Flew backwards for five minutes once, in winds of about 55 MPH - my stall speed was about 45MPH with light fuel, full throttle, and "full flaps". Sometimes Pilots have "Backwards Races", where the windspeed is above the lowest controllable speed of the airplane, so they end up facing into the wind, and flying backwards! Easy to hover in those conditions.

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What makes this hard to conceptualize is inertia is just a one vector system. In that example of wearing roller skates on a treadmill, your body's inertia is in relation to the rope that you're holding. It's keeping you stationary because you are not part of the treadmill's inertia. And if someone pushes you while you're holding, you go forward because that's another independent force. The assumption with the airplane question is that all forces are going on in one system.

Anyway, that's how I am thinking of it. This would be a lot easier to answer if the question actually said if the plane moves forward or not. My assumption is what if forward inertia is being canceled by the belt. The airplane may still take off depending on its design.

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And this is what makes this question ludicrous We're inventing a hypothetical that's using precise scientific theory. In real life, there are going to be the other variables that make the airplane lift off before its wheels self destruct from friction

Yep.

You guys are so narrow-minded. Unobtanium? I have stock houses full of that stuff! Static wings? Jet propulsion? Yea, right.

Clearly the OP is expecting one of us to answer with the OBVIOUS choice:

I'm going with no. If we have a hypothetical conveyor belt, then we can assume we have hypothetical tyres and wheels which will also withstand the forces of the speed the engine is capable of going at maximum power. In which case, the conveyor/wheels assembly is immobile, relative to each other, so we can ignore them, and we are just left with an aeroplane that is held still, as if the brakes/chocks are on.

And yes i'm British, and yes i fly aeroplanes

I hate you guys. I hate you guys, so very very much.

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Since this is such a mind trip...let me elaborate on the original thought I had. Now if we assume our airplane is a jet, then yes, its wings won't provide enough lift. Jets operate by having big forward thrust. But lets say in this hypothetical, our magic treadmill negates all the forward thrust. Now there can be other forces acting on the wings if they are large enough (gliders) and are driven by propellers. Lets say our plane is a B-17 (which had two props on either wing). With it, it's creating a vortex of air around the wing. So the more the propeller spins, the more potential for air to be able to lift the wings (with non forward thrust). And when friction is reduced, it can also then move forward on its own inertia.

So that's another hypothetical.....it can be either "yes" or "no" since this is so..... hypothetical!!!

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Nope, the engine will only provide a finite amount of thrust, be it jet or prop. Once at full power that's it, you're not getting any more. Just because a propellor blows air over the wing, doesn't mean it can lift itself.