A jet plane on a large treadmill

[Jong Lafitte]

Daniel is travelling tonight on a plane on a treadmill
I can see the red tail lights not heading for Spain
Oh and I can see Daniel continuously waving goodbye
God it looks like Daniel, why is his plane on a treadmill?
Oh God it looks like Daniel, why is his plane on a treadmill?

Or:

I went to Phoenix Arizona, stayed in Phoenix Arizona because my plane is on a treadmill ya;
Phoenix Arizona
Phoenix Arizona
Phoenix Arizona
Cuz my plane is on a treadmill oh yea
Keep on a rocking me baby!
Keep on a rocking me baby!

Or:

Im not back in the USSR!
You don't know how lucky you are

Or:

I like pleasure spiked with pain
And I have a treadmill for my plane
Treadmill for my plane
Treadmill for my plane


Or:

Silver wings shining in the sunlight
Roaring engines headed nowhere on a treadmill
They're neither taking you away, nor leaving me lonely
Silver wings staying well withing my sight

Or:

"Get to the Jet Plane - Treadmill contraption!!"

or:

Gimmie a ticket for an airplane
unless its on one of those treadmill things
In such case I got time to take a fast train
Lonely days are gone
I'm a coming home
my baby just wrote me a letter

Into the distance a ribbon of black
Stretched to no point of no turning back
A flight of fancy on a windswept field
Piloting my plane on a big treadmill
A magical treadmill is holding me fast how
Can I escape this irresistible grasp?

Ground Control to Major Tom
Your circuit's dead, there's something wrong
Can you hear me, Major Tom?
Can you hear me, Major Tom?
Yes, Wilson, I'm right here, the rocket ship was just on a treadmill behind the office.

or:
He was born in the summer of his 27th year
coming home to a place he'd never seen before
but the plane he had a ticket for was on a big treadmill
and so he never made it to Colorado
Rocky Mountain High Colorado
Rocky Mountain high Colorado

or:
And if I had a speed plane we wouldn't fly across the land
We'd put it on a giant treadmill
We'd drink margaritas and dance to mariachis
Put you on my speed plane, and we, we'd never even leave home

or:
Jump in the cockpit and start up the engines
Remove all the wheel blocks there's no time to waste
Gathering no speed as we have a treadmill runway
Not Gonna get airborne no matter how long we wait

or (OK, I'll stop...soon)
When I woke up I was all alone
With a broken heart and a ticket home
And I ask you now, tell me what would you do
You get yourself on a treadmill plane that's what you do
Cuz I traveled around and been all over this world and
Boys I ain't never seen nothin' like a Galway girl

Oh, right, and the one that keeps gettin stuck in my head when I see this thread:

Woah Oh Big ol' Jet Airliner
aint gonna carry me too far away
Got a treadmill for my Jet Airliner
And its here that I'm goinna stay!

[jono]

Not that his idea is workable but he's not talking about the wheels sliding he's talking about the wheels staying stationary and pulling the treadmill forward with the engine thrust. Again, reading fail or troll?

Good point, I was still imagining someone else's version of locked wheels. Just out of curiosity, though, how would that work as a troll? The idea of trolling people with nerdy physics crap is kind of unusual, you're opening up a whole new train of thought there.

[Flyoverland Captive]

Not that his idea is workable but he's not talking about the wheels sliding he's talking about the wheels staying stationary and pulling the treadmill forward with the engine thrust.

Exactly; I can walk on my treadmill (when it's not turned on) and make the belt move; couldn't the plane do the same?

[MagnificentUnicorn]

Exactly; I can walk on my treadmill (when it's not turned on) and make the belt move; couldn't the plane do the same?

Yes, but that's not part of the question.

[old goat]

'Cause I'm leaving on a jet plane, I know when I'll be back again. 'Cause babe it just won't go.
(Never knew John Denver wrote that--might explain why I hate it so much)

I don't want to hear a love song
I got on this airplane just to fly
And I know there's a treadmill below
And I guess that we're not moving and I think that I know why

[Jong Lafitte]

Exactly; I can walk on my treadmill (when it's not turned on) and make the belt move; couldn't the plane do the same?

So, what if the the plane could float above the treadmill? If it was like reverse magnets being used. Then wouldn't you be able to spin the treadmill as fast as you wanted to and the plane would still just float there, right? It seems like it could move forward relative to the non-treamill earth very easily. Like you could push it with a broomstick so even a little thrust should get you off of the treadmill, then you thrust up as you leave the magnet and the regular tires are on the runway in front of the treadmill then proceed down the runway to normal takeoff. So, really, does it only prevent takeoff if there is some (more than nominal) bit of friction in the system? There has to be a way to "push" the plane backwards, so the gear is used in the question for that purpose, it seems to me. If you could find a plane that can take off with locked tires or put a plane with skis on it, the treadmill would speed up and the skidding would just become more violent. Its not matching the wheel speed, its simulating the would-be ground speed based upon whatever infinite set of inputs are needed to do that. And also, no. Its a magical treadmill that's purpose is to match the would be ground speed so even if you try to push it with locked breaks, it responds as the ground would in all cases and cannot be defeated because it is magical. An exercise treadmill is not.

So if you have a plane which cannot take off with its wheels locked (that it doesn't skid forward under full thrust) it will just sit there at full thrust with the tires stuck to the ground. Its not going to move the ground, so the treadmill will respond the same way. It will exert exactly enough force to hold the belt as steady as, well, rock. Then, the plane will just sit there as it normally would.

This, also assumes that the treadmill in the question is plugged in and set to "on." If you can sneak out to the site in your plane and move the treadmill by locking the breaks and thrusting up (or, by throttling up a gyrocopter, or a 68 Chevelle SS with Posi) while its not operational is a different question.

[GeezerSteve]

If the airplane then starts its engines it will move forward along the treadmill, regardess of how fast the treadmill is going and will take off if the treadmill is long enough.

Yeah, but someone cunted up the original hypothetical to allow for the possibility of the airplane's wheels spinning at some absurdly fast rate and the wheel bearings burning up and failing, thus vitiating the essential premise of the original thought experiment. Those cunter-uppers assume away by implication the possibility that the treadmill bearings or other treadmill component might fail first, thus spotlighting the stoopidness of the cunting up and obvious motivation to invite an argument they will always win by tweaking the assumptions to frustrate anyone who might call horseshit on them, yet always denying their cunting up and obliquely attacking those who call out said cunting up. What we have here is the Padded Room in action.

[mcsquared]

Holy shit, are we still arguing about this?

[Peruvian]

What color is the plane?

[Jong Lafitte]

Yeah, but someone cunted up the original hypothetical to allow for the possibility of the airplane's wheels spinning at some absurdly fast rate and the wheel bearings burning up and failing, thus vitiating the essential premise of the original thought experiment. Those cunter-uppers assume away by implication the possibility that the treadmill bearings or other treadmill component might fail first, thus spotlighting the stoopidness of the cunting up and obvious motivation to invite an argument they will always win by tweaking the assumptions to frustrate anyone who might call horseshit on them, yet always denying their cunting up and obliquely attacking those who call out said cunting up. What we have here is the Padded Room in action.

bah. nevermind. I wanna know if two inflatable pilots can land a plane with no landing gear.

[JimmyCarter]

bah. nevermind. I wanna know if two inflatable pilots can land a plane with no landing gear.

Surely you can't be serious?

[flyandski365]

Yes, but that's not part of the question.

Huh, IDK about you but I've never been on a plane that got thrust from its wheels.

[iceman]

No, and don't call me Shirley.

[stuckathuntermtn]

Surely you can't be serious?

I'll have the fish

[mcski]

Is thrunting a type of thrust?

[Svengali]

Mcski, There are 4 types of thrust: piston/propeller, jet turbine, rocket, and pelvic
Does this help?

[MagnificentUnicorn]

Huh, IDK about you but I've never been on a plane that got thrust from its wheels.

Neither have I you moron. Have you actually read any of my posts? The quote you're responding to has nothing to do with powered wheels on an aircraft. My response that you quoted was in response to a post by flyoverland about a plane on a freewheeling treadmill with it's brakes on and the belt of the treadmill moving forward(opposite of normal) because of the plane's thrust.

If you're gonna take part in this idiotic conversation, try and keep up.

[mcski]

Mcski, There are 4 types of thrust: piston/propeller, jet turbine, rocket, and pelvic
Does this help?

So thrusting creates a time warp?

[El Chupacabra]

So thrusting creates a time warp?

Just a jump to the left!

[flyandski365]

Neither have I you moron. Have you actually read any of my posts? The quote you're responding to has nothing to do with powered wheels on an aircraft. My response that you quoted was in response to a post by flyoverland about a plane on a freewheeling treadmill with it's brakes on and the belt of the treadmill moving forward(opposite of normal) because of the plane's thrust.

If you're gonna take part in this idiotic conversation, try and keep up.

Well excuse me. He made mention of WALKING on a treadmill and making it move. You know how your feet move when you walk and it sort of propels you across the ground? Yeah, I haven't read the whole thread but your answer in the context of his question doesn't make any sense.

Ah fuck I read some further. I see what you're saying and agree. Disregard above.

[Jong Lafitte]

Ha! I did a bit of reading around on this. I like this explanation: Everybody's right!

I'll give this another try now.

Everybody understands that a jet can't take off unless it is moving forward. Everybody understands that the wheels of the plane are [pretty much] free wheels with brakes and do not have any power to drive the plane.

It is possible for the plane to remain stationary at a very high conveyor speed (and high thrust) if the pilot collaborates with the treadmill. If the pilot attempts to overcome it, though, then either the conveyor is 'perfect' (instantaneous speed adjustment and near infinite speed ability) or the plane can easily overcome it. Its just that if the pilot tries to do so, any conceivable conveyor you could actually build and run could easily be overcome. If the conveyor responds to the speed of the plane, it cannot respond quickly enough, nor accelerate quickly enough and the plane overcomes the treadmill speed easily. So it depends on how you interpret the phrase "matches the plane speed." You cannot use a conveyor to 'prevent' a plane from taking off but you can also have a plane sitting stationary on the conveyor with the belt passing under the plane at well over take-off speed, it would just require cooperation from the pilot. It would also still probably take very little thrust to keep it stationary even at high speeds until we were using a warp drive conveyor. I guess I dreamed up a warp drive conveyor or was reading the question as something that its not, like, "is it possible for a jet under take-off thrust to remain stationary on a conveyor belt?"

[old goat]

[QUOTE=flyandski365;4830465 Yeah, I haven't read the whole thread .[/QUOTE]

Has anyone? I hope not.

[Mustonen]

So, chewed on this for a while.....

Your first point just needs a FBD, as I described above (that sled example needs something though, I can't make out what you're describing there; every way I interpret that the torque on the wheel changes the required push force, but I think you'll get that with proper FBD's).

But your second point would be much better addressed if you take another look at calculus. While it's often imperfect for describing the real world (though no moreso than algebra, technically) the technique works perfectly for describing perfect systems like the treadmill imagined here. There's no logical reason to lock the wheels, there's nothing to physically cause that and the magic control system can't reach past the belt. So the question is what can it do and the answer is apply speed to belt. With changing speed we have acceleration and with acceleration we have force, in knowable quantities as shown a page or so back. You keep saying the control isn't designed to stop the plane and that's correct, but since matching the wheels' speed can only be achieved at forces that match the thrust that fact comes along for the ride.

Point conceded on the sled. Thanks for sticking with me. My hangup was around how the force was applied. If the application of force wasn't fixed to the wheel (as in the treadmill/airplane) then you're absolutely right. If you drop your rollerblades on a spinning treadmill, even if they're perfectly aligned and perfectly friction-free, they're going to flip right off the back.

Also conceded that the treadmill could theoretically oppose the thrust from the jet engines (up to the weakest interface). Just because it could, I'm not sure it would. Not as the question is worded. In a calculus world, maybe, but as described, there isn't a way for the system to ever begin to move.

Xkcd banned this question. Makes sense considering Jono

I think Jono's been pretty reasonable, here?

You would think so. But if the treadmill is to match the wheel spin, then the treadmill would have to
Move in a forward direction to match the none moving wells. Therefore matching the wheel speed as per the directive, still profit?

No? Interesting reframing, though.

Why are we assuming that the treadmill can't move forward? If the wheels never move, thereby never making the treadmill move backwards, the plane never moves. But it's clear that the engines will make the plane move forward. Thus the paradox.
If the wheels can't spin, thereby making the treadmill spin, can't the planes engine thrust force the plane forward, making the locked wheels drag the treadmill forward? And at a certain speed, can't the plane lift off?

If the jet engines have enough thrust to drag the wheels or treadmill..... that's an easier question for the enginerds to math out and (I think) a little bit beside the point.

My biggest problem was clearly displayed in our first runaround, where everybody tries to use the tools they have to answer whatever question is in front of them (When you're a hammer, everything looks like a nail; when you're an engineer, everything looks like an equation; when you're a physicist, everything looks like a force diagram) in spite of whether or not that was an appropriate response.

[stfu&gbtw]

Next time I've supposed to take a trip I don't want to go on, I'm just going to sneak a model plane and a little mini treadmill on board the real plane with me. I'll set up the rig in the bathroom and run the treadmill backwards with the model plane on it. The look on the pilot's face when our plane won't take off will be priceless.

[iceman]

Good plan, but hopefully the pilot won't be in the bathroom with you so I'm not sure how you're gonna see the look on his face.