Will the Plane Take-Off

Chris Luva Luva · Post by **Chris Luva Luva** » Mon Feb 05, 2007 4:46 pm

A plane is standing on a runway that can move (some sort of band conveyer).
The plane moves in one direction, while the conveyer moves in the opposite
direction. This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in opposite
direction).The question is:Will the plane take off or not?

BTW, I dont know the answer. yet. :lol:

Irn-Bru · Post by **Irn-Bru** » Mon Feb 05, 2007 4:50 pm

Methinks it will be spinning it's wheels, mostly. . .

Fios · Post by **Fios** » Mon Feb 05, 2007 5:03 pm

I think it will, it would seem that the jet engines, which utilize the air around the craft to create lift, would be able to compensate for the conveyor belt. That's purely speculation on my part but it would seem that the aircraft would still be able to create the conditions necessary for flight, the wheels would be toast though.

Jake · Post by **Jake** » Mon Feb 05, 2007 6:06 pm

Fios wrote:I think it will, it would seem that the jet engines, which utilize the air around the craft to create lift, would be able to compensate for the conveyor belt. That's purely speculation on my part but it would seem that the aircraft would still be able to create the conditions necessary for flight, the wheels would be toast though.

If the conveyer belt is tuned to the planes speed then I don't think it would.

REDEEMEDSKIN · Post by **REDEEMEDSKIN** » Mon Feb 05, 2007 6:39 pm

How many people are on board?

Countertrey · Post by **Countertrey** » Mon Feb 05, 2007 7:12 pm

It will fly. The aircraft will accelerate regardless the speed of the conveyor, because Newton's law still applies. The aircraft gains momentum due to the interaction of engine forces, with no relationship to the conveyor.

The only impact the conveyor would have would be to cause the wheels to turn faster than they ordinarily would, and would have no bearing on the ability of the plane to take off.

Hooligan · Post by **Hooligan** » Mon Feb 05, 2007 7:44 pm

Yes it would take off. The jet engines are pushing the body and wings of the plane forward. It isn't like a car, which relies on it's wheels to move it forward. Airplane wheels aren't powered by anything and are pretty much free-spinning, so a conveyor belt moving underneath them would probably have a very very minimal effect on the speed of the aircraft.

ATV · Post by **ATV** » Mon Feb 05, 2007 8:55 pm

Answer = Hell No.

Lift, which makes airplanes rise, is generated by air pressure beneath the wings. Wings, if you didn't know, are generally shaped with a convex upward side and a flat bottom side. This causes the air on the top side to have to travel a further distance than the air on the bottom side. This results in a change in the air pressures, literally pushing the wing upward. As long as the plane is moving fast enough, i.e. they have enough current of air passing past thier wings, they are able to generate enough lift to remain airborne. So, the conveyor belt wouldn't be much help - The whole earth, including the air currents, would have to be moving against the direction of the plane. If the plan is stationary, a humongous fan would be much more sucessful than the conveyor belt.

.....Not be demeaning, but I'm suprised none of you knew this.

Fios · Post by **Fios** » Mon Feb 05, 2007 9:16 pm

ATV - Didn't you contradict yourself? You say hell no and sort of provide a case for the plane to take off.
My understanding on this, having done some research, is that the wheels will spin at a very rapid rate but that the jets will continue to generate thrust, the static between the runway and the wheel wouldn't have an impact.
At least that's what all of these scientists said.

1niksder · Post by **1niksder** » Tue Feb 06, 2007 1:10 am

Depends if the pilot atempts to lift the plane and what the RPMs of the enginges are at the time of the attempt.

Of course I'm guessing, I mean what type of plane is it, some planes have verticle lift and once those engines a tilted that baby's gone.

ATV · Post by **ATV** » Tue Feb 06, 2007 1:26 am

Contradict myself? No, I think I was just explaining a different scanario.

Anyhow, it looks like this question was posed slightly differently in this other forum. Under their circumstances, who knows, the plane might be going fast enough to rip the landing gears off. There's too many other variables, questions that would need answering first.

skinz74 · Post by **skinz74** » Wed Feb 07, 2007 6:02 am

As an air traffic controller, I would have to somewhat agree w/ATV. A/C cannot takeoff without approx 25kts of head wind (amount variable based on size of a/c) to create/sustain lift. Since the A/C in question appears to be stationary on the conveyor, I do not think it is possible. On aircraft carriers, often at sea, there is no wind, and the carrier has to produce its own by turning into the wind full speed (classified kts.) Only then, can we launch A/C.

$.02

tcwest10 · Post by **tcwest10** » Thu Feb 08, 2007 6:07 am

skinz74 wrote:As an air traffic controller, I would have to somewhat agree w/ATV. A/C cannot takeoff without approx 25kts of head wind (amount variable based on size of a/c) to create/sustain lift. Since the A/C in question appears to be stationary on the conveyor, I do not think it is possible. On aircraft carriers, often at sea, there is no wind, and the carrier has to produce its own by turning into the wind full speed (classified kts.) Only then, can we launch A/C.

$.02

This is why Reagan fired your ass, Jester. ROTFALMAO

Anyways...scientists-schmeintists, cup. There's no lift, as noted. Try to picture the whole thing as a person on a treadmill.

Fios · Post by **Fios** » Thu Feb 08, 2007 7:35 am

Right but I have 1) yet to find a definitive answer and 2) that treadmill scenario is addressed in the link I posted. I still don't know what will happen, I am agnostic on this one.

nuskins · Post by **nuskins** » Thu Feb 08, 2007 11:48 am

The only speed that determines lift or flight is the speed of the air moving over the wings.

If the conveyor belt is matched to counter the forward progress of the plane it will not achieve the airspeed neccessary for flight.

Realistically if this worked their would be no need for runways for takeoffs and Aircraft carriers wouldn't use a steam catapult. Do you realize the time, money, and lives spent by the military and NASA trying to achieve VTOL?

If this worked it would have been done by now.

It will not take off b/c it is not making forward air speed.

DESkins · Post by **DESkins** » Thu Feb 08, 2007 11:58 am

I don't have to be on the plane, do I?

Fios · Post by **Fios** » Thu Feb 08, 2007 12:16 pm

DESkins wrote:I don't have to be on the plane, do I?

You have to be on the treadmill

Fios · Post by **Fios** » Thu Feb 08, 2007 12:17 pm

nuskins wrote:The only speed that determines lift or flight is the speed of the air moving over the wings.

If the conveyor belt is matched to counter the forward progress of the plane it will not achieve the airspeed neccessary for flight.

Realistically if this worked their would be no need for runways for takeoffs and Aircraft carriers wouldn't use a steam catapult. Do you realize the time, money, and lives spent by the military and NASA trying to achieve VTOL?

If this worked it would have been done by now.

It will not take off b/c it is not making forward air speed.

OK, that's the best explanation I have read thus far even though I have no idea what VTOL stands for.
I am not smart.

REDEEMEDSKIN · Post by **REDEEMEDSKIN** » Thu Feb 08, 2007 12:35 pm

Fios wrote:I am not smart.

Wow. A new sig line!!

joebagadonuts · Post by **joebagadonuts** » Thu Feb 08, 2007 1:08 pm

Fios wrote:
DESkins wrote:I don't have to be on the plane, do I?

You have to be on the treadmill

My guess is that DESkins will not take off.

JansenFan · Post by **JansenFan** » Thu Feb 08, 2007 2:26 pm

Fios wrote:
nuskins wrote:The only speed that determines lift or flight is the speed of the air moving over the wings.

If the conveyor belt is matched to counter the forward progress of the plane it will not achieve the airspeed neccessary for flight.

Realistically if this worked their would be no need for runways for takeoffs and Aircraft carriers wouldn't use a steam catapult. Do you realize the time, money, and lives spent by the military and NASA trying to achieve VTOL?

If this worked it would have been done by now.

It will not take off b/c it is not making forward air speed.

OK, that's the best explanation I have read thus far even though I have no idea what VTOL stands for.
I am not smart.

Vertical Take Off and Landing

The Harrier can take off whether the treadmill moves or not. It just tilts it's wings and uses the thrust to push up instead of forward.

DESkins · Post by **DESkins** » Thu Feb 08, 2007 3:54 pm

Darn straight I ain't taking off. I'm not sure I could even get up to highway speed, much less take off speed, even if I flapped my arms and said "pretty please".

UK Skins Fan · Post by **UK Skins Fan** » Thu Feb 08, 2007 4:30 pm

Fortunately, as I believe I have said before, I am enormously clever. I am therefore able to provide the answer. Or, on the other hand, I may be perfectly placed to make a complete horse's backside of myself.

The key thing to enable a conventional aircraft to fly is the movement of the aircraft's wings relative to the air around it. In other words, if the plane is moving forward through the air, the wings will generate lift. The speed required is determined by a tedious formula involving such stuff as rho v squared, and needn't bother any of us here.

Now, the trick of the question is to make us focus on the wheels resting on the conveyor, with the conveyor's motion stopping the aircraft from moving forward because the conveyor speed matches and counteracts the revolution of the wheels. However, the aircraft engines do not transmit their power through the wheels, but act to produce thrust through the air. Certainly, if we're talking about a jet, there's nothing that the conveyor is going to be able to do to stop the tens of thousands of pounds of thrust from the engines from driving the aircraft forward through the air.
I am therefore forced to conclude that the aircraft will take off, but it still seems damn strange. The key point is motion through the air, not force exerted through the wheels on to the ground. Will the conveyor stop the aircraft from moving forward at all? I think not.

Fios · Post by **Fios** » Thu Feb 08, 2007 4:52 pm

UK Skins Fan wrote:Fortunately, as I believe I have said before, I am enormously clever. I am therefore able to provide the answer. Or, on the other hand, I may be perfactly placed to make a complete horse's backside of myself.

The key thing to enable a conventional aircraft to fly is the movement of the aircraft's wings relative to the air around it. In other words, if the plane is moving forward through the air, the wings will generate lift. The speed required is determined by a tedious formula involving such stuff as rho v squared, and needn't bother any of us here.

Now, the trick of the question is to make us focus on the wheels resting on the conveyor, with the conveyor's motion stopping the aircraft from moving forward because the conveyor speed matches and counteracts the revolution of the wheels. However, the aircraft engines do not transmit their power through the wheels, but act to produce thrust through the air. Certainly, if we're talking about a jet, there's nothing that the conveyor is going to be able to do to stop the tens of thousands of pounds of thrust from the engines from driving the aircraft forward through the air.
I am therefore forced to conclude that the aircraft will take off, but it still seems damn strange. The key point is motion through the air, not force exerted through the wheels on to the ground. Will the conveyor stop the aircraft from moving forward at all? I think not.

That's what all of the yes answers I have read argue, that the wheels are essentially just used because 1) you have to land the thing and 2) setting the plane on the ground and simply scraping the hell out of the bottom is kind of dumb

Countertrey · Post by **Countertrey** » Thu Feb 08, 2007 5:13 pm

Anyways...scientists-schmeintists, cup. There's no lift, as noted. Try to picture the whole thing as a person on a treadmill.

Clearly, most folks here are thinking that aircraft use their wheels to provide propulsion. This is not a car. If you place a car on the hypothetical treadmill, your analogy is correct.

In the case of our aircraft, the propulsion forces will impart momentum irrespective the treadmill. The wheels, which are in contact with the treadmill, do not propel the plane.

The engines DO NOT CARE that there is a treadmill. They are interacting with the AIR, not the TREADMILL. They will force the plane forward NO MATTER WHAT speed the treadmill is travelling in the opposite direction.

UK Skins Fan gets it. Everyone else has fallen for the red herring of the conveyor belt... which has no bearing on whether the plane flys or not.

Ya'll got access to a treadmill? Buy one of those cheap, rubber band planes... try it yourself. Just be ready to catch the plane before it flies into the wall in front of the treadmill.