Mythbusters, Plane on a treadmill..

[dash8driver]

so tell me, just how fast do you have to spin the wheels to get the plane to stop in mid air?

Missin' the point: Spin the tires at a velocity of zero. With no tires, the airplane is firmly attached to the conveyor belt, it does not get to move forward through the air, it is earthbound.

Now, once the "airplane" is in flight, the tires are nearly as useless as the stewardesses.

no, i think you missed the point. the question wasnt "would a plane take off if it was bolted to a trailer/conveyor belt". sounds like we're re-writing the question to match our answers now.

i agree that the majority of the controversy is from thinking the plane will not have relative motion.. thats an assumption the reader is making.

now i dont know how it was where everyone else went to school, but where i went to school if you got a question wrong because you didnt understand the question or made an incorrect assumption in the process of solving the problem, you're still wrong.

 

[CFI2766]

Max,

Want to play some softball this year? It's almost that time...

Let's get together for that beer (x5) sometime.

-G

 

[Max Q]

Max,

Want to play some softball this year? It's almost that time...

Let's get together for that beer (x5) sometime.

-G

I'm down. Left-field, catcher, 3rd or even 4th string waterboy, I'm your guy.

You know me, man. Just tell me when and where. Tues-Thurs are my days off. They've got me on the back end of the power curve this month.

-Brett

 

[COOPERVANE]

Told





YA





SO!


"sounds like we're re-writing the question to match our answers now"

Dash, thats the finest explanation for this phenomenon.

People read the original question and make an assumption based in their own mind. When they realize they are wrong and feel DUMB they have to claim semantics so they can still be right.

 

[Captzaahlie]

I guess that would be me then. The demonstration portrayed on the show did not meet the elements of the test in a very necessary way. Namely, the conveyor belt (tarp) was not moving as fast as the plane's wheels were moving. As evidence, you can see the traffic cones marking the takeoff distance. If the tarp was being pulled the same speed as the wheels, the plane would not have passed a single cone. Instead, it passed the last one at lift off.

The error in the test design was moving the tarp at takeoff speed and not the plane's wheel speed which was faster.

I have not yet realized an error in my original thinking and do, in fact, insist that a plane tested under the right conditions will not take off.

MAYBE YOU CAN GET THE PILOT TO HOLD THE BRAKES (THE WAY I'M HOLDING THE CAP LOCKS KEY) TO HELP PROVE YOUR POINT!

If you really mean what you posted I feel sorry for the entire world of aviation, because you just might be related to flying in "hopefully" some small fashion................

uke:


You really are kidding right?

 

[JimNtexas]

Consider:

F = MA

with respect to the horizontal axis of the plane (looked at from the side). The plane has some mass, M. There is a force from the engines directed along the horizontal axis. This is the force that causes the airplane to accelerate down the runway on a 'normal' runway.

Now consider a runway moving in the opposite direction of takeoff. The force from the engines is still the same. The mass is still the same. Therefore the acceleration down the runway will be the same regardless of the movement of the runway!

 

[Captzaahlie]

Consider:

F = MA

with respect to the horizontal axis of the plane (looked at from the side). The plane has some mass, M. There is a force from the engines directed along the horizontal axis. This is the force that causes the airplane to accelerate down the runway on a 'normal' runway.

Now consider a runway moving in the opposite direction of takeoff. The force from the engines is still the same. The mass is still the same. Therefore the acceleration down the runway will be the same regardless of the movement of the runway!

Another excellent explanation for a concept that really is not that overwhelmingly difficult to grasp.
We are talking really basic physics here. Nicely put Jim.
:beer:

 

[Say Again Over]

Consider:

F = MA

with respect to the horizontal axis of the plane (looked at from the side). The plane has some mass, M. There is a force from the engines directed along the horizontal axis. This is the force that causes the airplane to accelerate down the runway on a 'normal' runway.

Now consider a runway moving in the opposite direction of takeoff. The force from the engines is still the same. The mass is still the same. Therefore the acceleration down the runway will be the same regardless of the movement of the runway!

__________________

Yes I agree, great post, although sad to say, I was in the no fly camp several months ago, this formula straightens things out.

 

[ImbracableCrunk]

Told





YA





SO!


"sounds like we're re-writing the question to match our answers now"

Dash, thats the finest explanation for this phenomenon.

People read the original question and make an assumption based in their own mind. When they realize they are wrong and feel DUMB they have to claim semantics so they can still be right.

Let's say you had a giant treadmill with an airplane on it.

As you add power and begin to move for the takoff roll, the treadmill speeds up and keeps the plane in the same relative position. As the plane goes faster, the treadmill speeds up, always maintaining the aircraft's relative position.

Again, the original question is right there.

When I read your question, the answer seems to me, No the airplane won't fly. No relative motion = no fly.

Now, if you want to change your question, to what they did on MythBusters, then the plane will fly.

Oh, and I had Kari Byron (MythBuster CHick) on my flight from ANC the other day. Niiiice.

 

[wrxpilot]

I'm also surprised there is still any doubt about the outcome - particularly after the Mythbusters show. Anyway, another way to think about it is this:

Let's say an airplane is on a perfectly smooth, frozen lake. The friction coefficient is essentially zero, and the parking brake is on. When takeoff power is set, will the airplane takeoff? If you agree that it does, then why would a treadmill have any effect on the takeoff? Using the lake example, it is clear that the airplane does not care what is happening at the wheels.

 

[Papps]

if youre answer is anything but "yes it will" than you need to read up on the difference between ground speed and airspeed

 

[Max Q]

Again, the original question is right there.

When I read your question, the answer seems to me, No the airplane won't fly. No relative motion = no fly.

Now, if you want to change your question, to what they did on MythBusters, then the plane will fly.

Oh, and I had Kari Byron (MythBuster CHick) on my flight from ANC the other day. Niiiice.

That wasn't the original question. Mythbusters didn't "change" anything. Even if it WAS the question, one should realize that "...treadmill speeds up keeping the plane in the same relative position" is about the dumbest most ignorant POS thing a pilot can say.

It is no surprise, however, that one would say that particular phrase was in the original question. Most naysayers are unable to swallow their pride after realizing how stupid they sound arguing on the internet for months about something they should know about, but don't.

I would hit Kari like the fist of an angry god.

-Brett

 

[siucavflight]

It will fly.

 

[WabiSabi]

I think this thread is about 10 pages too long

 

[CFI2766]

I would hit Kari like the fist of an angry god.

-Brett[/quote]

True dat.

However, it should be noted that her mass, much like the length of this debate, has increased over the years. Just sayin'.