This very question gets a mention on Wikipedia - but it's due for deletion and i'm guessing it's probably because it's a nonsensical question.
However, they did have this to say.
Some clever clogs on Wikipedia wrote:
The confusion surrounding the question most likely arises because the problem is poorly worded. While in the air there are only two forces which have any effect on an aircraft: pressure and friction with the surrounding gas. Ground speed is irrelevant. In the real world it is possible, with the right plane and a fast headwind, to have zero ground speed and stay in the air.
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phattslagg wrote:
Yes, there would be some rolling resistance, probably insignificant. Especially since the plane would have moved forwards off the treadmill in a the first few seconds.
But it's a 'magical' treadmill, so I think we can assume it will perfectly match the plane's wheel rotation at every stage of the process?
It's even more nonsensical when you add the word "magical"
The wheels still aren't anything to do with propelling the plane.
No, but they are to do with allowing the plane to be propelled. If the plane just had metal spikes which scraped across the tarmac, then takeoff would be a little more..interesting, wouldn't you say?
so here we have an idea of a better question.
"if you took the wheels and legs off a plane so it just sat on the ground. would it achieve lift?"
phattslagg wrote:
Yes, there would be some rolling resistance, probably insignificant. Especially since the plane would have moved forwards off the treadmill in a the first few seconds.
But it's a 'magical' treadmill, so I think we can assume it will perfectly match the plane's wheel rotation at every stage of the process?
It's even more nonsensical when you add the word "magical"
The wheels still aren't anything to do with propelling the plane.
No, but they are to do with allowing the plane to be propelled. If the plane just had metal spikes which scraped across the tarmac, then takeoff would be a little more..interesting, wouldn't you say?
True, but it doesn't alter my point.
Also, ski-planes and water planes manage without wheels. Some gliders take off on a skid on grass. Wheels obviously have the lowest friction on tarmac though.
Baggypants wrote:
"if you took the wheels and legs off a plane so it just sat on the ground. would it achieve lift?"
Yes, if the engine was powerful enough and it survived the damage.
or to the logical extreme,
"can a plane hover?"
answer: no.
Answer, sort of. Gliders can achieve lift in the right conditions without moving forwards with respect to the ground. They can suddenly take off vertically (or more likely flip over) with a sudden gust of headwind, which is why they get tied down.
Last edited by kalmar on Tue Dec 12, 2006 1:51 pm 0, edited 1 time in total.
phattslagg wrote:
Yes, there would be some rolling resistance, probably insignificant. Especially since the plane would have moved forwards off the treadmill in a the first few seconds.
But it's a 'magical' treadmill, so I think we can assume it will perfectly match the plane's wheel rotation at every stage of the process?
It's even more nonsensical when you add the word "magical"
The wheels still aren't anything to do with propelling the plane.
No, but they are to do with allowing the plane to be propelled. If the plane just had metal spikes which scraped across the tarmac, then takeoff would be a little more..interesting, wouldn't you say?
True, but it doesn't alter my point.
Also, ski-planes and water planes manage without wheels. Some gliders take off on a skid on grass. Wheels obviously have the lowest friction on tarmac though.
Well, yes. But the whole point of this question is:
If one could completely negate the [rotation>forward movement] of the planes wheels using an admittedly non-existent technology, would the energy from the plane's engines be completely spent in that particular exchange, or would they still somehow create lift?
Baggypants wrote:
"if you took the wheels and legs off a plane so it just sat on the ground. would it achieve lift?"
Yes, if the engine was powerful enough and it survived the damage.
how about if the plane has no wheels or legs and has a bloody great rope tied to the tail to restrict forwards motion so the only airflow is provided by the engine?
and as I'm trying to provide a real world example we'll say the plane is a cessna.
A no wheeld, no legged, bound-by-the-tail cessna. will it fly^H^H^H^H^H^^H^H? edit: achive lift.
