Well if I was doing the test I would have an F-35 and just take off vertically anyways. So there.



The question is too broad therefore it cannot be accurately answered, way too many unknowns.

 

True. An engine alone does not cause lift, unless it's a STOVL F-35, or another vertical take off plane such as a Harrier.

 

A plane could not take off simply because of prop wash. First of all, the prop wash really only hits the fuselage and base of the wings. Because the air is rotating, the most it would do is roll the plane over, but even that is pretty much impossible. Second, even if the base of the wings could provide enough lift to get the plane to fly, it would be impossible to control because the ailerons, which control roll, are on the wing tips. There is no air flow over the ailerons, so the P-factor would instantly roll the plane over.


And as was said, ground effect is the compression of air between the ground and the wings. If the prop wash doesn't create lift throughout the entire wing surface, flight, even within ground effect, is impossible.

 

LOL This picked right up where it left off...

I tivo'd the show and watched it today. When it came on I was like "Of cource it would take off. The tires have nothing to do with the foward acceleration produced by the engine."

Looking back at my original post, I wasn't so sure back then.

 

The plane must have a throttle body spacer and e-fans to produce lift.

 

I think the answer is no. The conveyor isn't matching the wheel speed, it's matching the plane speed. It wouldn't matter if it had wheels, skis or floats. If it's moving backwards as fast as it's moving forwards that equals 0mph which would not create enough air for lift.

 

This is a rediculous argument. I can not believe that the Mythbusters actually wasted an episode trying to prove something that is obviously impossible. The laws of physics define the fact that the plane will NOT fly without a minimum amount of airflow over the wing. If the airflow is not present, no lift. Period. A stationary aircraft does not encounter airflow, unless there is a VERY strong headwind.

 

Haha, many people haven't taken physics 101 huh??

It's obvious the plane WILL MOVE forward, and produce lift. Thrust is provided by the engines, not the wheels. If you ever took time to draw a vector diagram you'd notice that the wheels would just spin twice as fast as the plane is traveling at takeoff. The only effect of the wheels is friction, which is neglible.

I've seen this arguement before, it's been beaten to death but sometimes it's not worth the effort to argue something so retarded. It's like trying to tell someone 1+1=2 but they keep saying 3, sometimes you cut your losses....

I guess some people are just slow.

 

So will a float-plane take off going upstream on a river?

Same principle, only you replace the boat skis with wheels on a conveyor and add a little more friction. The thrust of the props or jets are more than enough to overcome the friction in the wheel bearings and between the wheels and conveyor.

 

Well some folks on here get what's going on.

 

Amen.

 

Yes it will because the stream is not going to go 100mph. So the float plane will have air moving over the wings. It will take longer to take off than if off still water.

As far as the plane on the conveyor, if the conveyor is going fast enough so that the plane stays in the same relative position to the person viewing, no it will not take off as the air over the wings is a speed of zero except for that air being pushed by the propeller. And that is not enough on a real plane to make it fly. It may be on a model, but not in the real world.
I have recorded the episode, but have not had time to watch it, but if they got a plane to fly when it has a forward speed of 100mph and the conveyor has a backward speed of 100mph, they cheated.

 

Yes it will take off. Read the sentence carefully.

 

Kingfish, you are getting sucked in by the "trick" to this question. There is no doubt that if a plane can't move forward, that it will not be able to generate lift under the wings. The trick is that you "imagine" the plane is not going to move forward, but in fact it really does.

I am going to revisit the little red wagon analogy to help you to understand why. A key factor to remember is that the wheels on the airplane are "freewheels", not drive wheels.

Imagine a long conveyor, like those in an airport. Now right beside this long conveyor, is a sidewalk. You have a little red wagon. You place the wagon on the conveyor. You stand on the sidewalk beside the conveyor.

You start pulling the wagon along, you walking on the sidewalk, the wagon rolling along right behind you , off to your right, on the conveyor.

The conveyor is off at this point, but but it can be turned on to roll either way, and the speed of the conveyor can be modulated.

So, the conveyor is off, you are walking along at 3 mph, walking on the sidewalk, pulling the wagon along right behind you , except it is just off your right, rolling along on the conveyor.

At this point, the speed of the wagon is 3 mph. (Because you are the force that is propelling the wagon along, and you are walking 3 mph)

Now, someone turns on the conveyor, and sets the speed to 10 mph. Your walking speed is still 3 mph. What do you think the mph of the wagon is? Granted, the wheels are doing the equivalent of 10 mph, but isn't the wagon still just going 3 mph? (because the wheels are freewheeling)

Now, some one actually reverses the direction of the conveyor. Now it is going 20 mph in the other direction. But you are still walking along the sidewalk, pulling the little red wagon, at 3 mph. What speed is the wagon moving? Granted, the wheels are now spinning the other way at the equivalent of 20 mph. But what is the wagon doing? Isn't it still going forward at 3 mph?

This is just to demonstrate that since the wheels are freewheeling, and not the source of propulsion, it doesn't matter to the source of propulsion what the wheels are doing at what speed or even which direction they are rolling.

In the case of the airplane, the prop pushing air backwards is the source of propulsion, and it doesn't care what the wheels are doing.

 

You need to remove this bad idea from your head and really think about how an aircraft flies.

Why would the aircraft not move? All the wheels do on an aircraft is reduce friction. Unlike a car, truck or person the airplane does not push against the ground. It pushes against the air. So, the propulsion device (prop or jet engine) still will be able to function just as it would under any other condition. The aircraft will go forward just as it normally would the only difference is that the wheels would be going twice the normal speed. But forget about the wheels, they do nothing!