A jet plane on a large treadmill

**Dexter Rutecki** · 08-20-2008, 10:43 AM

I said I was on a treadmill, you moron! How could I possibly achieve airspeed?

**iscariot** · 08-20-2008, 10:54 AM

Originally Posted by Beaver

Are you "no takeoff" guys fucking stupid or what? Twice for those who don't get it.

The jet plane will take off because it is irrelavant how fast it is going in relation to the ground as it is not driven by wheels but by jets (hence the name of the craft). It's wheels will be spinning like a motherfucker but it will have it's normal airspeed and thus take to the air like, well, a jet. It better have some good wheel berings and some well ballanced wheels.

If the plane does not use it's jets it will not move therefore the treadmill will never need to turn. If it uses it's jets it will begin to move forward, as it moves forward the treadmill will begin to move backwards twice as fast as the jet is moving forward. The jet will continue to accelerate gaining airspeed while the tradmill continues to accelerate twice as fast as the jet. Eventually (slightly longer than normal due to added rolling resistance) the jet will take off. It really does not matter how fast the ground appears to be passing by because like I stated, ground speed is irrelevant. The jets push air not ground so who fucking cares if it is on a treadmill.

LMFAO

That must be some sweet B.C. bud...

**Shaggy** · 11-20-2008, 09:39 PM

The mythbusters episode is being repeated on discovery channel right now....

**mock vomit** · 03-23-2009, 08:05 AM

Bump for parakeets in a cage on a treadmill... do they take off?

**mock vomit** · 11-02-2009, 12:41 PM

Another "what the hell" thread bump...

**Crock** · 11-02-2009, 01:04 PM

suppose the swallows carried it with a string?

**akokskis** · 11-04-2009, 04:46 PM

There are really 24 pages of this?

Wow mags, you've impressed me yet again.

PS. [ame="http://www.youtube.com/watch?v=0KsdMuhYJPw"]YouTube - Mythbusters - Plane on a Conveyor Belt[/ame] for mythbusters showing the plante takeoff.

**eldereldo** · 11-04-2009, 06:51 PM

OK so you skeptics still disbelievers?

**Johnny Deep** · 11-05-2009, 10:07 AM

Originally Posted by eldereldo

OK so you skeptics still disbelievers?

Not enough dope smoked on this one.

**Liveezy** · 11-05-2009, 10:24 AM

This thread is funny shit. Soo many dumb fucks out there. Kinda made me feel smart!

**jmf** · 11-05-2009, 04:17 PM

I didn't read the whole thing, but I did get the jist... Beaver did not take off, but he was pretty fucking high already.

**Tunco** · 04-12-2012, 01:45 PM

**belgian** · 04-12-2012, 02:00 PM

Jesus... I was fucking dumb in high school. Thanks for reminding me.

**tetzen** · 04-12-2012, 02:01 PM

Originally Posted by Tunco

**Tuckerman** · 04-12-2012, 02:19 PM

fake..........................

**Ted Striker** · 04-12-2012, 04:15 PM

Fuck, this thread again?

The answer is that the question is wrong.

Let's say the airplane is on floats, and is attempting to take off from a river. It's pointed up the river (against the current), and the water speed is equal to the max speed of the airplane. Will it take off? No. Why? Because the airspeed is zero.

It could be restated that the force of the river is equal to the force of the propeller.

Now I know someone is going to point out that the prop is acting on the air not the water, but the bottom line is that both forces are acting on the airframe equally, but in opposite directions. Another example would be if you turned the engine off and tied the plane to a tree. That could be restated as the force of the river is equal to the force of the rope (even though the rope is acting on the tree, not the water).

If that doesn't work for you, think of a powerful fan that's securely attached to the ground. It may move a lot or air, but it won't move itself if it can't exert enough force to break free of its attachment.

Now, the tricky part is that when you put the airplane on wheels, there isn't enough friction (or connection) between the airframe and the treadmill to prevent the airplane from moving. The wheel bearings are meant to roll. Spinning wheels apply so little force that the airplane can easily overcome that force, and will move forward. The plane takes off because the premise of the treadmill question isn't attainable.

**GeezerSteve** · 04-12-2012, 04:50 PM

Originally Posted by pisteoff

The plane takes off because the premise of the treadmill question isn't attainable.

The OP makes no mention of a treadmill. It talks about a conveyor belt which, in theory, could be two miles long.

**flyandski365** · 04-12-2012, 05:40 PM

Originally Posted by Big Steve

The OP makes no mention of a treadmill. It talks about a conveyor belt which, in theory, could be two miles long.

It could be a thousand miles long, the answer is the same.

**GeezerSteve** · 04-12-2012, 06:05 PM

Yup, it would be the same answer. I was responding to this, per my interpretation of "the treadmill question isn't attainable," a rather clumsy phrase, which I interpreted to mean that thrust of the jets would move the jet forward, off the treadmill, onto the runway. I can't figure out what else he could have meant by the phrase "the treadmill question isn't attainable."

Originally Posted by pisteoff

The wheel bearings are meant to roll. Spinning wheels apply so little force that the airplane can easily overcome that force, and will move forward. The plane takes off because the premise of the treadmill question isn't attainable.

Hugh Conway · 04-12-2012, 06:13 PM

Originally Posted by Big Steve

Yup, it would be the same answer. I was responding to this, per my interpretation of "the treadmill question isn't attainable," a rather clumsy phrase, which I interpreted to mean that thrust of the jets would move the jet forward, off the treadmill, onto the runway:

Your interpretation isn't allowed by the OP

This conveyor has a control system that tracks the planes speed and tunes the speed of the conveyor to be exactly the same (but in the opposite direction)

which is why the whole things stupid

**GeezerSteve** · 04-12-2012, 06:17 PM

That the whole thing is stupid is hereby acknowledged. Doesn't matter what speed the conveyor belt is going -- well, unless it's so fast that the plane's wheel bearings get red hot and seize up.

**Mustonen** · 04-12-2012, 06:31 PM

Originally Posted by pisteoff

It could be restated that the force of the river is equal to the force of the propeller.

No. No it couldn't. That's not what it is.

It was never posited in the premise that the treadmill would act in such a way that it would restrict the forward speed of the airplane to zero.

Quite the opposite. The treadmill only moves backwards if the plane moves forwards. That's the fucking premise. Go read it again. Think about it for like five seconds. If the plane doesn't move forwards, the treadmill doesn't move backwards. If the plane moves forwards, how can it be standing fucking still?

The plane takes off. The wheels spin twice as fast. It isn't a physics riddle, it's a logic riddle.