Weird scientific questions

[Kszchroink]

that's because some people are fucking retarded and have no idea of the functions wheels serve in an airplane (no offense)

[Nfsjunkie91]

Oh hey, maybe if the wheels start moving fast enough, and depending on the heat generated and the materials used in the wheel, the wheels would cease up!

EDIT: Or break off!

[blackdevil0742]

brrrrrrrrrrap blackdevil0742 you're a horrible poster, do you even read the threads you post in?

I gave up reading the posts after the second page after all the crap.

OK I get it now I never really thought it through...so my anwser is still "it won't lift"
The plane needs air to lift.

[a-4-year-old]

The flaw is that wheels don't spin freely under all that metal. The plane has too much weight, there is a whole shitload of friction and the wheels wouldn't spin twice as fast to overcome the treadmill. Pulling the carpet out from under an RC car doesn't prove shit.

[Kszchroink]

well, if there was a "whole ****load of friction", the wheels would have a hard time spinning on normal runways too

[a-4-year-old]

You try getting huge wheels to spin twice the speed of a plane taking off with a plane sitting on top of them and see how difficult it would be.

[Espadon]

Alright..this has dragged on long enough.

No, the plane won't generate any lift.  For the plane to stay on the theoretical treadmill, if would have to have it's engines going to match the speed of the treadmill (i.e. making it stationary).  Because the treadmill   only moves the wheels of the plane and not the entire column of air directly above the treadmill, there is no air passing beneath the wings and thus no lift. 

If the plane were to exceed the speed of the treadmill and actually move forward, drawing air beneath the wings, then you'd have lift.  But all that air moving under the wing just isn't there when it stays stationary on a treadmill.  All that'd happen is a change of tires after a while.

I was reading this whole fiasco part. Chroink is correct, due to the fact that there is a reasoning flaw here in Geologist's post.

First of all, we shall say that Boeing has invented a totally frictionless bearing for its 747's wheels. They have put it on a super treadmill that is moving at 300 mph westward. Held at the moment with a massive clamp, the 747 is lowered onto the treadmill, facing eastward. The aircraft is NOT moving, however, the wheels are spinning at the rate so that it would go at 300mph westward IF they were the wheels on a car (as you see, there are no engines hooked up to an aircraft's wheels). Now say, the pilot cranks the throttle up to 300 mph airspeed. The airplane will disregard the fact that the treadmill is moving 300mph WESTWARD and instead zoom off into the sky EASTWARD. This is because the aircraft's engines "bites into" the stationary air. Right before the aircraft takes off, the wheels would be moving at the equivalent of moving westward at 600 mph. Despite the fact that the treadmill is moving so fast, the air, at least at the engine's height, is stationary. Gases have low friction, being what they are. This is the same reason why we have air currents, because the atmosphere moves at different velocities at different latitudes (the principle is related to why figure skaters spin faster when they tuck everything in).

If this is still too confusing, then perhaps your time would be spent better on various other activities.

[LtKillroy]

Wait, since the aircraft is moving the opposite direction as the gear, wouldn't they blow off or am I just stupid? The wheels can't spin two directions.

[Espadon]

No they won't. You guys are too automotive-minded. An aircraft's wheels move freely opposite to whichever direction more force is applied. An aircraft moving in the opposite direction would only make the wheels spin faster, and vice versa.

The rotational speed of an aircraft's wheels has no bearing on its airspeed.

[LtKillroy]

Yes but isn't the treadmill going ------> and the plane is going <------. Since the wheels can't travel both directions, it would like break. Or am I missing something?
Wait I'm dumb disregard that.

[Graham]

Yes but isn't the treadmill going ------> and the plane is going <------. Since the wheels can't travel both directions, it would like break. Or am I missing something?
Wait I'm dumb disregard that.

When you run on a treadmill you go <-- and the treadmill goes ---> your legs don't break off then.

[KorrupT MerC]

OK... so this is the answer... the plane will lift off?

Its what i gather, since the wheels arent there to move the plane but to reduce friction, that means the wheels are just going to move twice as fast as they would on a regular runway and since the engines are actually pushing the plane, they (along with the wheels) work together to overcome the treadmill and eventually create enough air flow to lift off.

Now is that correct?

[Espadon]

Yes you are.

@ Killroy: Here, let's look.

You can test this out for yourself by putting  a pencil between your hands and moving one hand one way, and the other the other way. The pencil does not change the fact that you can move your hands in different directions.

As an addendum to cap it all, before anyone else so vehemently babbles about ridiculous dogmas such as how an aircraft is affected by things such as groundspeed, post your credentials. I personally fly a Cessna Skyhawk, designed, built and flown r/c aircraft, and have an extensive library of various world aircraft, etc.
*stares at 4yo*


If you only have a superficial understanding of what you're talking about, you shouldn't sound so sure.

[LtKillroy]

I think the biggest thing is are the tires frictionless unough to not drag it enough to let it go fast enough to let it lift off. But I once again could be wrong, I am no expert of treadmill planes.
Wow I wrote that before I saw espadon's post, Ima psychic lol.

[blackdevil0742]

...the plane still needs to move through air in a relatively fast speed in order to lift. Even if it manages to move faster than the treadmill with its engines it will only fall down from it resulting in a crash.

[KorrupT MerC]

Now your just trying to make a whole bunch of 'what if...' situations, basically the plane will lift off, never said it had to fly

[Espadon]

The friction that is present in real life planes' wheels is negligible compared to the aircraft's lifting power and engine thrust. Otherwise, aircraft could NOT take off in the first place! Consider that the 747 can lift off at 875,000 lb, and cruise at mach 0.85. Definitely what friction you have is not going to play a big role in takeoff speed.

blackdevil, you just can't get the car syndrome out of your head, right? Maybe you should take somethings by faith.

The plane WILL LIFT OFF, and WILL FLY, IF the aircraft's takeoff velocity is achieved, regardless of how fast the ground is moving.

[LtKillroy]

Re:
Why is this topic still going it's been solved.
Lock.

[Amblin]

The fact that you guys haven't stopped replying seriously just goes to show how much inane and ridiculously stupid shit you're used to.

[Espadon]

Because there are people on the internet who feel they are powerful and knowledgeable just because their faces cannot be seen. They'll argue for the sake of argument because the facelessness of the internet appears to put everyone on the same level. If you don't know squat about something, you STILL don't know squat.

@ amblin. I just couldn't pass this one up, man. I just couldn't.