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Max: >it was a trick question, too funny. There's no trick involved. >if not for the PROP! (if it was a JET) the (true) >answer is (STILL) a resounding NO! No difference -- prop, jet, ducted fan or rocket. All will takeoff in (almost) the exact normal distance. >requires...

Macal's example is so excellent that I'm gonna expand on it for a moment. Put a guy in a wheel chair and ask him to propel himself in the normal wheelchair manner (through the wheels). Put the guy out on this giant runway treadmill and the dude who controls the runway will DOMINATE the...

Max: >do you feel any airspeed relative to your >"wings" running on a treadmill? Of course not, but the point you're missing is that the plane isn't "running on a treadmill" -- it's "running through the air" and happens to just be sitting on a treadmill. >the problem assumes the the...

The wheelchair example is perfect. Nice! JB

Just so you know Max, I agree with your conclusion that in the above scenario, the plane hasn't taken off -- but the above isn't a valid representation of the stated problem. To make your problem come into line with the stated problem let's continue it ... Above you have achieved a steady...

Wayne's the man. JB

Of course that's where the answer lies -- it takes airspeed to the wing for a plane to takeoff ... we agree perfectly. Please explain what keeps the airplane from accelerating down the runway and gaining airspeed to the wing. JB

The problem never states or insinuates that "the belt is moving the same speed as the thrust". JB

Cubano, you and Surf are both correct -- it takes wind moving over the wings to create lift. The part you both are missing is that the plane moves down the runway *just as usual* and the wings create lift *just as usual*. The key to the whole problem is the realizatin that the conveyor...

I sure hope the little smiley face means your joking -- otherwise you're just wrong. JB

If your saying that in this scenario, there is now a *sliding* friction between the conveyer and the wheels, I would disagree -- the wheels are rolling quite freely. If your just saying that a wheel turning twice as fast creates more *rolling* friction, than I agree -- but comparably, there...

acronym: >In fact, the plane would take off faster than >normal, with said induced air flow providing >a headwind. You're thinking is correct here, but I'm not sure whether the minimal take-off distance advantage from the treadmill induced headwind will be greater than the friction drag...

Haroki: >It's a trick question JB. I find it an interesting question, and perhaps counter-intuitive, but personally, I don't find anything "trick" about it. It's a straightforward question with a straightforward answer. >The wheels and thrust from the jets are disconnected. >In this...

acronym: >The airliner could not take off, due to the higher >wing loading, as opposed to a cessna which >generates an additional degree of lift vector >forces from prop wash, plus vastly lower wing >loading. Not much mind you, but it helps a bit. Jet, prop, Cessna, Boeing ... all...

Let me reword the question and make the scenario more specific... I am in the cockpit and flying a simple Cessna 172. (single engine, takeoff speed ~75mph, max speed ~150mph). You are in the control tower. In your hand you hold a dial control with which you control the speed of the entire...

Let me reword the question and make the scenario more specific... I am in the cockpit and flying a simple Cessna 172. (single engine, takeoff speed ~75mph, max speed ~150mph). You are in the control tower. In your hand you hold a dial control with which you control the speed of the entire...

You are correct in your ultimate answer, but I don't completely understand your described method so I can't say if your reasoning is correct. JB

TL: >Correct, the wheels don't drive the plane. Good, we agree. >But in your scenario the conveyor belt is >moving in the opposite direction at the >same speed. Yes it is. >The equivalent of climbing up a >down escalator. Uhh... I thought we agreed that the wheels weren't...

Why not? The wheels don't drive the plane. JB

I find it interesting that people believe that the plane will not move on this giant treadmill. If I stick a car in a giant wind tunnel and turn the wind up to 100mph does anyone believe that the car will still not move forward? Two different mediums, two different propulsions. The wind...