The plane and the conveyor belt were NOT traveling at the same speed. If they were, the plane would be stationary. It wasnt hard to see the plane was moving forward pretty fast, obviously faster than the belt. So its ground speed was still fast enough to reach takeoff speed to produce enough lift on the wings to fly. The prop doesnt make the plane fly, the wings do. Shut an engine down during flight, what happens, you glide. Cut your wings off in flight, see what happens.

http://www.youtube.com/watch?v=4owlyCOzDiE

If you want to see something that is ACCURATE and TRUE that proves the plane will fly - click that link.

Even on a REAL TREADMILL a RC PLANE will TAKE OFF.

Also, please listen to his EXPLANATION. The guy knows what he's talking about.

The testing that Adam and Jamie did is VALID. This youtube video corroborates their findings - INDEPENDENTLY.

MythMod

I think the guys got it right on the show. The plane should take off from the conveyor. However, their explanation of the physics was completely wrong. The plane does not take off because of the propeller moving air over the wings. The plane takes off because the propeller pulls the plane through the air, this movement of air over the entire wing allows the plane to fly. If the propeller were enough to keep the plane aloft, then why are the wings so large? By this theory you would only have to have enough wing directly behind the propeller. This can also be proven by testing with a "pusher" style aircraft, one with the propeller behind the wing. It would also take off with this test. To further clarify this whole thing, they should have been measuring air velocity at the wings, not ground speed at the wheels.

You no-flys truly are pathetic. You had your proof RIGHT IN FRONT OF YOU, yet, since the results didn't agree with your erroneous mindset about the problem, you dismiss reality because it's just too bitter to choke down.

I'll tell you what...take a basic physics class and learn how to draw a force diagram before you claim to know what you're talking about in the future.

You have got to be kidding. How can anyone claim there is a "myth" here? Not to mention that it was busted. This is my first post, I just created the screen name, as I could not sit on my hands after this debacle.

First of all the "myth", in this case, has been stated in conflicting statements. The first is that the conveyor is moving at the same rate the plane is in the opposite direction. The second that the plane can take off from the said conveyor at a stand still because the speeds are matched. These two statements are not the same.

The plane in this case was capable of taking off at 25 mph. Now, what you ding bats need to under stand is that is "air speed" not "ground speed". In the first case above the plane can take off because: 1.) The conveyor is moving at 25 mph, 2) the air speed is 25 mph. In this case the plane can take off because regardless of what the conveyor is doing the plane is going 25mph. It doesn't matter if the dang thing was trying to take off on a pile of cranberry sauce. Relative to the groud and therefore the air as well the plane is going 25 mph. Relative to the conveyor the plane is going 50 mph.

Now if the second case is that of the plane not moving relative to the ground, also mentioned a number of times on the show. Then the conveyor is moving 25 mph. The plane however, is moving at zero (0) air speed. Meaning that from the viewers perspective, the plane is standing still and TRULY matching the conveyor speed, as it is not moving. To the plane the speed would be zero, because a plane measures air speed not ground. If they hooked up a speedometer to the wheels they would see that the plane is actually moving at 25 mph. Now this is critical for everyone out there. THE PLANE WILL NOT TAKE OFF IN THIS CASE!! I've seen things as inane as "oh well the propeller moves the air over the wings and it will take off" UM, you sir just created a hover craft, or vertical take off plane. And if you can warp physics to actually make that happen, the air force wants you right now.

Of these two cases only one even makes sense to test. Why would you test the one where the plane simply beats the conveyor for speed and eventually gets enough speed to take off? Why not just state "can a plane move faster than and conveyor"? The only myth that makes sense, though minimally at that, is can a plane matching the speed of a conveyor and not moving relative to the ground take off. However, someone with basic knowledge of physics could have answered that one before you waste perfectly good busting time on the show.

Really poor myth to try, and though the laugh at the arguments here are funny, the fact that the entire crew of the show just made a fool of themselves is kind of sad. Not to mention the taunting they did after they claimed "busted" at the end, not even realizing what they were trying to prove.

You people who are saying that they didn't test the myth right are downright WRONG! You interpret the idea of the conveyor belt matching the speed of the plane's wheels as the idea that it will remain stationary. This stems for YOUR ignorance. I mean honestly, did you even WATCH the show? They explained it QUITE well at the end. It's not about will the plane be able to take off if it remains stationary. If you want to know if that works, go buy a toy plane and hold it in place while you run the engine. It's about will the plane be able to overcome the opposite force of the treadmill. They didn't test the myth wrong, you interpreted the myth wrong. If you don't understand that, then there's no hope for you.

quote:

Originally posted by szuprbeazt:
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.

There is a relation, but that is regardless. The myth was that if the propeller was not pushing the plane forward, ie it was an equal speed, then the plan would not take off, so it does not matter whether the plane can provide forward motion, only if it can take off WITHOUT motion (which basic physics teaches it can not becuase it is a closed system, so no force to push the plane into the air.)

[QUOTE]Originally posted by cbarn:
I have to say, it wasn't what my wife and I expected.

Cbarn said it well: If they stuck to the "rules" they set, the planes would appear stationary. Obviously the real plane was moving faster than the truck-pulled tarp because the plane move horizontally out of the camera field.

Try this though experiment (maybe a future real one): Imagine a plane suspended over a stationary conveyor. It won't "take off". Then match the conveyor speed to the planes take-off speed. Will the plane take off? Nope. Run the convery at 2x take-off speed. Will the plane take off? Nope.

MB is one of my 3 fav shows, but they seriously dropped the science ball on this one and I suspect it's for the revisit opportunity.

.

I guess I sort of naively hoped this would settle the issue, but alas now instead of having to explain why the plane takes off, we need to explain why the plane takes of AND why the test was valid.

this myth is all about how its worded. the words are what confuse people. cuz ur mind makes u want to have the plane stay. make any sense? i thought about this a bunch and i was for sure they did it wrong, and should have had the treadmill go faster but thats not what is being questioned. anyways i confused myself for something that was easy to understand.

How can so many people just not get it? The plane never was supposed to stay "stationary". That was an image you created in your mind when told the question. The plane was always going to move forwards at the same speed the belt/tarp was moving backwards.

The original question was a trick question to cause you to think the plane would be stationary. You fell for the trick hook, line, and sinker.

The plane will move forwards and take off in every revisit, no matter how many times you moan "they did it wrong!!"

That was beautiful!

Are there still any original subhuman fools around here?

That is what the will-fly group was called by a bunch of the no-fly people. Every time a no-fly was converted to will-fly, we welcomed them as a new subhuman fool.

We took it as a badge of honor.

The subhuman fools have now been proven right beyond question, but I see that the no-fly group is still as ungracious as ever.

I have lost all faith in humanity. I am truly disappointed in the MythBusters on this one. This myth should never have made it past the so-called "science content" segment. A plane is able to fly because air is passing over and under the wings at a certain velocity. This myth is a question of relativity. If the plane and the conveyor belt are moving at the same speed but in different directions, the plane is still NOT moving relative to the air. The ultralight plane in the episode took off because it was moving fast enough relative to the air to create lift under the wings. The conveyor belt was not moving fast enough to keep the plane stationary relative to the air. If you can't understand this concept, I would suggest opening a physics or calculus III book. Books can usually be found in libraries. If you cannot find a library, try google searching "how a plane flies."

Speed doesn't matter. The only force acting on the conveyor is the planes weight- ONLY THE PLANE'S WEIGHT. If you take the average circumference of the tires, and multiply it by the weight of the plane, you get the total amount of force acting on the conveyor for each tire rotation- NO MATTER HOW FAST THEY SPIN!

And that is why the plane took-off.

i joined the site just to comment on this myth, as all the educated ppl have mentioned this myth was done wrong. simple physics a wing needs air going across it to create lift. a propeller blade is a wing, it has air flowing across it because the engine rotates it..thus causing FORWARD motion, this forward motion then creates air flowing over the wing, causing UPWARD motion. the whole reason a helicopter has its propeller pointing the way it does is so it can lift from a still position, if the myth is truly can a plane on a treadmill matching its speed take off...meaning plane has no forward motion, the answer is 100% no its the same reason air craft carriers steer into the wind during take offs, as someone else mentioned, the only way to test this myth correctly is to tie a rope to the planes tail and see what happens, it would be like a box fan...some wind... the only way this could work would be if there was a ridiculous head wind....which was not in the myth..and for those who say watch the show...i say "what were you watching" the plane didn't stand still, it moved faster than the treadmill and thus moved forward if you noticed there were no side camera shots showing the plane lifting from a stationary position, all angled shots, and even in those you saw it passing cones, while on the ground.....come on ppl...its a physics problem for a reason, not a myth...just science, if you want a better reason, my dads a pilot, when in the holding pattern we rev the engine while standing still to make sure it operating correctly, the reason we don't take off? the brakes are engaged and thus we stand still....so you could say "ive tested the myth" it doesn't happen...sorry folks

quote:

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

Nothing of the sort!

Take a look at the very first message on this thread. Mythmod typed the "classic" wording of the myth. It doesn't say anything about limiting the plane's speed. It can go however fast or slow that it wants. It's up to the conveyor to match whatever speed the plane is going.

Furthermore, it's silly to ask whether or not the plane will take off if you don't allow it to try to reach it's normal take-off speed (which it certainly can do).

No, the Mythbuster's did it EXACTLY right!

Later!

Those objecting to the way the plane took off seem to have a problem with the fact that the plane did not stand still on the belt. Folks, you still aren't getting it.

Of course, that's the whole point. The conveyor belt simply cannot hold the plane back. The belt has no effect on what the propeller is doing to the air. The plane, driven by acting on the air - not the ground - cannot stay in one place on the conveyor belt during normal takeoff acceleration.

I too just created a screen name today to put my 2 cents in but big tank stole my thunder.

Imagine an air craft carrier, Ship speed + wind speed + air craft ground speed over the deck = air speed.

Air speed over flight surfaces means difference in air pressure due to shape provides lift.

Why do you think we tie the planes down on the flight deck. If you measure the speed of this ultralight at the wheel hub, you will see it could not possibly match the tredmill.

I can only come to the conclusion that all you no-flys lack the simple sense to comprehend a physics problem.

If you don't understand the problem, which more than half of you newbies don't, then stop talking.