The wheels don't move an airplane, the propeller (Lets stick with a small, single engine, high wing plane with a convenional empenage and rudder and a fixed propeller in a tractor configuration) pulls it forward by moving the air. Anything that applies to a wing applies to a propeller or rotor which are all things that create lift when air is moving over them. An aircraft absolutely will take off if the wheels are not locked.

I'm also convinced that the treadmill experiments do not cause a tremendous amount of wear on an aircrafts landing gear. The grease that goes on a small aircraft is good until the manufacturer specifies that you change it. Aeroshell grease is some neat ****. Its actually still usable when you change it, and it has an absurd operating temperature range. (All the way from balls cold to rage hot) Aircraft tires are actually good for life. They can be re-treaded an infinite amount of times as long as the husk and cordline of the tire are not damaged.

It might be better to ask if an airplane will take off with its brakes locked. The answer is most definately no. If we're using the aircraft type I outlined as an example it would generate enough thrust to nose over and run the propeller into the ground until the engine quit.

Or you could fix it in place, with a barrier. In which case the motor mounts (which are not designed with the aircraft being fixed in place in design) would seperate from the aircraft (which they are indeed designed to do when they are being extremely stressed so that a possibly or partially unmoored engine becomes a completely unmoored engine and moves free of the aircraft) and become a spinning cloud of death.



So what happens when a fixed plane is run, will it take off? Extreme maybe. The empenage of almost any aircraft is in the slipstream of the propeller, as are the leading edges of the wings. In my experience while running an aircraft stationary (Locked and chocked) once you reach a certain RPM the wings will start to generate enough lift to buffet the plane, and in a few cases caused it to skip over the chocks. Take it even further and the elevator (secondary control surface, the one that makes pitch happen) in a neuteral position will begin to level the aircraft, bringing the tail off of the ground.

Edit: Forgot to add. The fastest the wheels will spin on the treadmill is about twice as fast as the minimum takeoff speed of the aircraft. This is not nearly as fast as the wheels on an aircraft can spin while in the air. (think non-retractable landing gear)

I know they're extremely solid and would survive any normal situation. But I'm being humorous and suggesting things that exceed normal. Like 1 million MPH or something, that sort of extreme.



How do you come to that conclusion? The treadmill isn't going the same speed as the airplane is going forward (in which case I'd agree). It's trying to negate the airplane from moving at ALL. Which means the treadmill will spin at far greater speeds than the airplane is moving forward, in an attempt to stop the airplane. Basically, treadmill increases speed until the airplane isn't moving. Since that won't happen, treadmill increases speed until something explodes (obscene speeds, like the 1 million MPH I suggested earlier).

Also, takeoff speed of a given aircraft is not a number, it is a formula with more than a few variables.

But lets simplify it. The speed the aircraft moves on the ground is irrelevant. The density and speed of the air moving over the wings is what matters.

Maybe you missed it, but I'm not arguing whether the plane could take off normally, it definitely could/would. I'm not debating the physics behind lift and all that. All I'm talking about is the other component, which is the treadmill.

The treadmill isn't going to stop the airplane from moving, I'm just talking about its attempt to do so, and the humorous physics involved with a treadmill trying to break the speed of light to stop a plane that can't be stopped, and the poor wheels that have to be subjected to those forces.

you leave the shrimp out of this

Its the way the question is phrased. If the treadmill is moving backwards as fast as the plane moves forwards it is going about twice as fast no?

This question was brought up in my turbines class, and that was the first thing the instructor pointed out.

It is a dumb question designed to make dumb people look really dumb.

If it's phrased that way it's boring. I like the (probably incorrect :P) phrasing of it trying to keep the plane stopped, not just matching wheel speed from the plane moving forward.

You know, the word "math" is rather close to "meth".

It's a trick question designed to make people think about a domain where they have no experience. cf. the Wason selection task, which deals with abstract logic (the material conditional).

"There are four cards on the table. One side of each card has a number, and the other has a solid color. The four cards show 1, 2, red, and blue. Which cards do you need to flip over to check the truth value of the following proposition: if a card has the number 2, then it has a blue back?"

The vast majority of people who take this test fail because of the problem domain. If you rephrase the question, people always get it correct:

"There are four cards on the table. One side of each card has the age of a customer, and the other says what drink they ordered. The four cards show 16, 22, coke, and whiskey. How many cards do you need to flip over to check that nobody under-aged is drinking liquor?"

The reason people get this problem wrong is because they automatically relate the question to what they have experienced, namely road vehicles like bicycles and cars, which will be successfully stopped by a treadmill. Context and experience is how we deal with problems. So don't think you're hot **** just because you're a domain expert and you can accurately reason about the problem.

Don't judge people for being wrong, judge them for disagreeing with you after you explain it.

Why can't I judge a person who willingly goes into a debate about a field that they have no experience in. Should I just leave the Creationists alone because they have not taken a single biology class, even though they are doing their best to prevent the teaching of science and replace it with a religious belief that is untestable via the scientific method?

it's sad how long it took me to realize you only have to check the 2 card and the red card.

that's an interesting example, is there a name for this phenomenon?

Because this isn't a debate, it's a logic puzzle. The problem is deliberately worded to make it sound like the plane is held stationary by the treadmill. The only reason it becomes a debate is because of disastrously stupid people like Alice Shade who refused to accept an explanation when it was offered.

People answer questions about fields they have no experience in all the time. Those people are called students.

I thought you were suggesting that the plane would begin to move so fast that, given that the treadmill must match it, the wheels would eventually spin twice as fast as the plane could possibly move on the ground with no air resistance (i.e. the plane is moving forward but never taking off, the treadmill is moving backward at the same speed).

Sounds like what you're actually saying is that to "make up for the lag" the treadmill would have to accelerate infinitely fast. But even the suggestion of such means the plane is already moving faster than the treadmill, when in fact they must be the same. If a = (vf - vi)/t what you are really describing is an acceleration where t = 0, which means a is undefined. I'm assuming that the calculus version of this breaks down in a similar fashion. I think for this to work you need to throw out the whole notion of traditional acceleration and assume a magical speed matching mechanism. Or just live with the idea that the treadmill will accelerate using a feedback loop and there will always be some minor mismatch of velocity as long as the plane is accelerating. Which, as far as I can tell is fine and has no affect on the experiment.

I would consider dividing by zero to be in agreement with my assessment of things exploding/melting down/etc. But yes, I'm just implying that it'd basically be undefined acceleration.

Wow. Physics. Yuck. I preferred this when it was jokes about .999



Yeah, trick questions are an interesting phenomenon. Lazy brain and all that. Y'know like the good ol' "If a plane crashes right smack on the border between U.S. and Canada, where do you bury the survivors?" Of course, most of the trick questions I know work best if spoken rather than written.

How many of each kind of animal did Moses take on the ark?

If the cakemaker weighs 200 lbs, and the grocer weighs 150 lbs, what does the butcher weigh?

Etc. Etc. C'mon, people, let's list more

2



he weighs meat

Moses didn't take any animals on the ark, dumbass.

the bible recorded the event wrong

my posting is bad

Best comeback today.