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

[mamba20]

No relative wind = no flight.

 

[Occam's Razor]

I just miss this thread.

Me too!

It's a totem of the Forum. A sign that rational professionals (and SWA/FO) can vigorously disagree on a hypothetical that is simply applied physics.

Go back (when you're reeeeeally bored!) and note the number of posts that don't address the issue, or even the science of the issue...but only the poster.

I attended a squadron reunion a month ago and used the Plane-On-A-Treadmill question to change the subject when a couple of my buddies were reminiscing about the time I ripped the basket off a KC-130 over the Sea of Japan. I left the table just as their argument over the solution got heated, satisfied that I'd just inititiated two brethren into the "Fraternal Order Of The POATA".

It's viral among pilots.

 

[molson247]

How big of a plane? If its a CRJ-900 flown by Mesa.....then of course

 

[Bob Runday]

I thought I would dust off this old gem to kill the PIC thread.

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.

Would you ever be able to take off?

GO!!

hang on, i need more info to work out this problem.....

okay, what is the weight of the aircraft?
what is the tail number?
what is the barometric pressure, is it standard?
is a revenue flight, ferry flight, charter, or just a Mx flight.
what is the brand of the treadmill?
does the aircraft have a parachute?

 

[grog_sit_reserv]

Regardless of how fast its going on that treadmill, the FA will always call up and ask you to warm it up over wing.

 

[CopilotDoug]

Uuuugh...I got to the second page and was amazed by the abundance of idiocy. Read this slowly and carefully, as I will only type it once:

The forward thrust is produced by the engines...not the wheels.

The treadmill will not be able to hold the airplane still in one place, no matter how fast it can potentially spin past wheel limitation speeds.

Therefore...it's an impossible scenario. As soon as power is applied, the airplane will roll forward off the treadmill

Now...back to the canary thing...I think the plane would weigh 1,000 lbs less...no?

 

[jws717]

The tires would overspeed, and there would be a little more drag. If it had enough power to overcome the extra friction, can a sea plane take off upstream on a river? yes.

 

[The_Russian]

RTFQ x 2!!!!!!

 

[jws717]

RTFQ x 2!!!!!!

LTFP= Learn The F'in Physics.

The question is invalid and does not make sense.

"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."

How can a treadmill hold down an airplane. this thread is stupid thats it i quit flightinfo.

 

[The_Russian]

LTFP= Learn The F'in Physics.

The question is invalid and does not make sense.

"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."

How can a treadmill hold down an airplane. this thread is stupid thats it i quit flightinfo.

Nah, you can't just quit!

Because there is NO wind flowing over the wings, the aircaft will not lift off. The hypothetical is that the aircraft maintains the same position.

Of course the question is invalid. Someone would have to buid a treadmill that has unlimited speed which can adjust itself to resist the thrust from the aircraft while compensating for changes in that thrust. Not gonna happen.

I think it's funny how people bring up the Mythbusters as a possibility to prove this thing. Those guys don't know the first thing about aviaiton. In all their pressurization experiments, they pressurized the aircraft WELL above 14.7:1! It was something to the tune of 343:1!

"Oh yeah, now the plane is pressurized. And look......Buster's head imploded!"

:laugh:

 

[PCL_128]

Because there is NO wind flowing over the wings, the aircaft will not lift off.

There would be air flowing over the wings. It's physically impossible for a treadmill to stop an aircraft from moving forward because the wheels don't produce the thrust to move the aircraft forward.

The hypothetical is that the aircraft maintains the same position.

Again, that's impossible. The question was written in a way that doesn't fit with physics. No amount of opposing speed from the treadmill would ever be able to hold the aircraft from moving forward.

 

[mrnolmts]

Amazing how little it takes to get this going again...

 

[The_Russian]

Amazing how little it takes to get this going again...

Just a little bump......

 

[The_Russian]

There would be air flowing over the wings. It's physically impossible for a treadmill to stop an aircraft from moving forward because the wheels don't produce the thrust to move the aircraft forward.

No, there wouldn't. The hypothetical is that the treadmill is able to retain the aircraft from moving forward. The treadmill is able to compensate for wheel friction and thrust. Therefore, the aircraft does not move forward through the air surrounding the wings.

RTFQ......again.

Again, that's impossible. The question was written in a way that doesn't fit with physics. No amount of opposing speed from the treadmill would ever be able to hold the aircraft from moving forward.

What about wheel bearing and tire friction? The treadmill would have to turn at an exponetial amount, but it would work. This would cause the aircraft to not fly.

Try to think outside the box a bit.

 

[The_Russian]

Anyone here need some pizza and mountain dew?