just wondering what adam said. did he not say that when the plane started off he just "floored it". if that's true then he started pulling the conveyor belt faster than the plane make the plane able to take off . b/c it looked like to me that he didn't take off until after the cones.

This was such a terrible waste of these guys talent. They #1 proved nothing of relevance, and #2 compared apples to oranges. Ofcourse the plane was going to take off. They did not compare the planes RELATIVE speed to the belt as a measure of it taking off or not. You could pull the belt at a gazillion miles an hour and as long as the tires and bearings held up, the plane would still take off! Its just like jerking a table cloth out from under some flowers. The planes ability to take off is relative to the speed of the air around it, not the belt or the runway. This is why planes take off in a shorter distance going into the wind versus with it.

I'm not whining, but I want to know:

What was the plane's airspeed when it took off?

How far did it travel on the conveyor belt?

How far did it travel on the runway?

That was a terrible experiment. The whole basis for the myth was that the airplane could take off from a treadmill traveling at the same speed as the aircraft. Unfortunetly during their testing they failed to keep the aircraft and the treadmill at the same speed. It is clearly evident from the video that the aircraft is accelerating faster than the treadmill is being pulled. If they were moving at the same speed the aircraft would not be passing all the cones while on the treadmill...it would remain in a stationary position relative to the cones.

The physics are totally wrong, an aircraft doesn't fly because of a propeller, ie a glider. It flys because of the air flow over the wings creating lift. If you were to run 20 mph down a road your hair would blow in the wind stream being created. If you run 20 mph on a treadmill your hair will look just as pretty as when your standing in place. Its the same principle with a wing.

The myth is a scam. They need to retry the myth with a pilot that can keep the plane at the same speed as the treadmill.

quote:

Originally posted by minimythbuster:
i think that they totally

quote:

half-assed

it because when they were explaining the myth they said it as if the plane isnt moving forward on the tredmill but when they actually the did the myth the plane ACTUALLY WAS MOVING FORWARD and was able to get some thrust and achieve flight so i think they need to re-do this one

LOL! It's ok, your upset. I would probably be upset to if I argued a point that defied all educated thought.

cbarn is completely right. There is so much controversy over this myth because it was so poorly explained. What they said the myth was, was not what they experimented.

quote:

I have to say, it wasn't what my wife and I expected. It's 100% understandable that if the plane is moving, it's going to take off - that's simple physics. What we were EXPECTING (take note for a revisit!) was that the plane and treadmill would match speeds - i.e. that the plane would remain stationary with respect to the ground. That's what the early explanations of the myth said - the plane moves x MPH one way, the treadmill moves x MPH the other way, the result being that the plane doesn't move forward or backward with respect to the ground. In both the model and full-scale tests, the pilot overaccelerated - of course it took off.

Do it again and keep the plane still - that would be the REAL test. :-)

quote:

I have to say, it wasn't what my wife and I expected. It's 100% understandable that if the plane is moving, it's going to take off - that's simple physics. What we were EXPECTING (take note for a revisit!) was that the plane and treadmill would match speeds - i.e. that the plane would remain stationary with respect to the ground. That's what the early explanations of the myth said - the plane moves x MPH one way, the treadmill moves x MPH the other way, the result being that the plane doesn't move forward or backward with respect to the ground. In both the model and full-scale tests, the pilot overaccelerated - of course it took off.

Do it again and keep the plane still - that would be the REAL test. :-)

quote:

i think that they totally
quote:
half-assed
it because when they were explaining the myth they said it as if the plane isnt moving forward on the tredmill but when they actually the did the myth the plane ACTUALLY WAS MOVING FORWARD and was able to get some thrust and achieve flight so i think they need to re-do this one

Need a little cheese to go with that whine, fellas?

This myth was done improperly. The test they designed only had the treadmill match the takeoff speed of the plane, when they should have matched the speed of the plane's wheels at the takeoff speed. Thats what the true problem was. It needs to be redone to have the treadmill adjust its speed to the speed of the wheels.

The experiment for taking the plane off was done wrong, therefore, no proven conclusion can be drawn. I am and Aerospace student at the University of Texas, and in the most beginner class we had we learned that to take off you need lift under the wings, which is caused by the flow of air... not the turning of the wheels. The fact is simple that the plane took off, but it had forward motion, therefore, it's takeoff speed was greater than that of the receeding tarp. You might as well have proven that a plane can take off from a runway!!!! Show if you can take a plane off from a conveyor or whatever you want to call it... if the plane is stationary due to the EQUAL speeds of the plane itself and the conveyor. Then, this arguement will be settled. I think you will find that it is NOT possible.

as you can all see, this is my first post on this forum, so great was my sense of disappointment at this attempt to bust a myth. that was not a conveyor belt. the only reason anyone would even suggest this as a possible way to take-off would so that the plane could take off without moving forward at all. why else would anyone care? they wouldnt.
picture this. youve got an airplane on top of a mountain (somehow) and you want to take off... so you put it on a conveyor belt and it somehow magically gains lift even though it has no runway to work with, and is able to take off in say -- ten feet. essentially you wouldnt even need a conveyor belt, (or ten feet)just something like a reverse dynomometer to spin the wheels of the plane, but give it no room for forward movement.
the fact that a planes wheels can free spin twice as fast as they would normally just to take off doesnt prove anything, and i dont think thats what the creator of this myth had in mind.

u guys dont seem 2 understand that theres no relation 2 how fast the wheels r moving and whether or not the plane will move foward. the treadmill could have been going 200mph, and the propellor would have still pushed the plane foward. as long as the wheels can handle the speed, u would see that same result every time.

I think they blew this one. The whole object of the conveyor belt was to keep the plane from moving. The plane still moved. Thus not busted.

I think they would have better luck tying the plane with a long rope to keep it from gaining forward motion while still allowing it to gain upward motion and trying that instead of a treadmill.

They needed to account for the forward motion of the plane. They did not measure how far it took the plane to take off while on the conveyor belt. I'm betting it was the same distance as off the belt.

Excuse me, but as the videotape proves, the planes (both scale and lifesized) were moving. As the tape clearly shows, the plane was NOT traveling at the same speed of the treadmill, as the plane was moving FORWARD in relation to the pylons that were on either side of the runway. Therefore, air WAS moving under the wings by the action of the movement, NOT THE PROPELLOR.
Do you REALLY think that the NAVY would spend BILLIONS of dollars on catapult systems for aircraft carriers, if they could have just gotten away with having a treadmill instead.
GET WITH THE PROGRAM PEOPLE. It is all physics, just like the pilot Mark said:
If I move the air provides lift, if the treadmil matches my speed, then the plane will be a brick.
This has NOT been proven at all.

I understany why the plane did take off but there is a few things that I see wrong with this.
1) How many RPM's was the plane turning to acheive flight on the runway?
2) How many RPM's did the plane turn during the convayor flight to get to the AIR SPEED of 25mph to take flight?

If the plane takes X RPM's to take flight and Y RPM's to take flight on a conveyor then the myth is not busted.

The thrust of the engine going at a higher RPM means that the conveyor belt speed should have been matched.

But alas I am no physasist or spelling B champion.

You are missing the point. The belt was going faster than the plane's takeoff speed.
You want the treadmill to go fast enough to prevent the plane from taking off, which physics says(and was just proven) that it CANNOT do.
Sorry that the mythbusters cannot rearrange physics to suit you.
The plane's forward motion can ONLY be negated if you make the plane's forward motion be from the wheels, like a car. A plane's forward motion comes from the propeller. The propeller is not affected by the treadmill, therefor the myth is busted. As shown.

Presuming the 'conveyor belt' was moving at 25 mph and the plane was not powered, it would be moving backwards at 25 mph. When the prop turns sufficiently to pull the plane forward (without the tarp) at 25 mph it will have lift off, but when on the tarp, the forward speed is cancelled by the reverse speed of the 'conveyor belt'. Therefore the plane moving forward at 25 mph means the engine is revving sufficient to overcome the tarp plus 25 mph (total 50 mph) and creating lift off at its required forward speed.

Ok, it's time for confessions. How many pilots out there thought the plane wouldn't take off?



We saw at least one honest one on the show. I'm more surprised by the pilot's prediction than the test results. How much more could be asked for than a real airplane? Good job guys. Obviously there was some element of safety risk to doing this one. Congradulations.

I'm such a fan but they blew it on this one. If they had thought through the small scale test and remembered HS Physics. There are two sources of drag on the plane. The friction of the wheels and the plan-form drag through the air. The reason the small and full scale moved forward is that by resting on the treadmill they did not have to overcome the air resistance and could move forward as evidenced by the tape. The only reason the planes "lifted" was due to forward motion and airflow over the wings.
The true test is to exactly match the speed of the conveyor which by subtracting the plan-form drag will require a higher speed for the moving surface than the steady state speed for take-off. On the full scale test they also used an indicated airspeed which also takes into account natural wind. This too needed to be eliminated. They need to recount the results of this one or condemn a whole generation to a false urban legand.

I wanna see you "can't fly" guys describe the mechanism that CAN keep the plane motionless while the belt is moving, despite
the amount of power the plane's motor can deliver.
By the strict wording, if the plane moves, the treadmill opposes the motion. Instantaneously.
So by the strict wording, the plane can't move at all, because of the treadmill.. the treadmill speed doesn't change, and the
sound of one hand clapping is heard 'round the world, and who shaves the barber if there's no one to hear the tree fall.
Meanwhile, in the real world, the plane moves. And takes off.

I'm not sure the actual myth here. The test was just a faux treadmill causing friction against the wheels on a plane trying to take off. Seems like the spirit of the myth would be that the plane stay stationary and basically hover off. Otherwise a gusty head wind would pose more of a problem for takeoff than the friction of the wheels. If the plane is allowed to progress forward, than it's just a plane taking off. The treadmill is negligible.