Conceptual Puzzle: Runway Belt

[Toddzilla]

Originally Posted by Brillig

For that matter, I already posted why people arrive at two different answers, so the discussion is over anyway.

Way to shit on a cool thread, asshat.

[QuikSand]

I'll take Brillig, and lay the points.

[Glengoyne]

After reading some of the myriad posts here, I think I can more completely state the sentiment I tried to impart back on the first page.

Seriously looking at the problem, it should be obvious that the significant thrust of the engines can't be overcome by a runway turning the wheels of the plane backwards.

At the same time the problem is worded such that it is a fact that the treadmill will match the speed of the wheels in the opposite direction. That makes it clear that the runway can somehow exert a force on the body of the plane, exactly opposing the engines. It makes no difference that it isn't physically possible, once a reader makes the assumption that is fact.

So I'm happy with my original conclusion that the plane would take off, but one can never really satisfy someone who latches onto the principle that the runway can magically match the wheels, cancelling any movement.

[Glengoyne]

Originally Posted by QuikSand

I'll take Brillig, and lay the points.

I'm taking the points in this one, all the way. I'm close to declaring it a mortal lock.

[firebirds]

When I first read the question I just knew that the plane couldn’t take off. Even after reading all the posts plus what Cecil had to say, I was ready to say that all those that have achieved a higher level of education than mine just plain couldn’t see the forest for the trees. I know that an airplane flies once sufficient lift is created by the uneven air flow past the wings. Since, for all practical purposes, we can’t directly increase the speed of the air passing over an airplane’s wings we increase the speed of the wings passing thru the air. So that means we have to move the airplane. Yet my first impression of the question wouldn’t allow the plane to move. But then a light bulb turned on to illuminate this dim wit and I came up with a different interpretation of the question. I decided the intent of the conveyor belt was to counteract/nullify any forward movement of the airplane as achieved by the forward rotation of its wheels as a result of the thrust provided/generated by the engine(s). So looking at the situation from that angle I decided that would basically remove all resistance that the airplane would encounter with the conveyor belt regardless of how magically impossibly fast either turns, in essence removing thier existance/relevance. With that in mind, the first vision that came to me was the airplane being in a state of pseudo levitation or, if you prefer, the airplane hanging from a string, with nothing preventing the thrust of the engine(s) to move the airplane forward.

[Glengoyne]

How did the Mythbusters air this episode, and no one here bump this thread?

I forgot to watch the show. So did the plane take off?

My bet is still yes. I'll also bet that very few people will be convinced to change their opinion.

[gstelmack]

I kept forgetting to come and find this thread; too much WOOF work to do.

Yes, the plane took off and was mostly unaffected by the conveyor. They ended up pulling a tarp under the plane backwards at above takeoff speed and it had no effect whatsoever. They started with a small-scale test where a radio-controlled plane had no problem running off the end of a typical work-out treadmill going above takeoff speed. Best part was the pilot of the plane saying he'd be stuck in place, and was in absolute shock after he took off with absolutely no trouble whatsoever.

Great episode. And yes, I'm sure lots of people will attempt to find flaws in the methodology, probably focusing on how the dragged tarp differed from a treadmill. I was 100% convinced they got it right though.

[Glengoyne]

Originally Posted by gstelmack

I kept forgetting to come and find this thread; too much WOOF work to do.

Yes, the plane took off and was mostly unaffected by the conveyor. They ended up pulling a tarp under the plane backwards at above takeoff speed and it had no effect whatsoever. They started with a small-scale test where a radio-controlled plane had no problem running off the end of a typical work-out treadmill going above takeoff speed. Best part was the pilot of the plane saying he'd be stuck in place, and was in absolute shock after he took off with absolutely no trouble whatsoever.

Great episode. And yes, I'm sure lots of people will attempt to find flaws in the methodology, probably focusing on how the dragged tarp differed from a treadmill. I was 100% convinced they got it right though.

Cool. I wondered how they were going to pull off the treadmill/conveyor belt. I just noted that my response about five posts up still neatly ties up my position on this one.

[DaddyTorgo]

MYTHBUSTERS FTW!!!!

[st.cronin]

I agree with Glengoyne 100%.