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+--- Thread: Will it fly? (/showthread.php?tid=6807)
- CaptainHenreh - 12-20-2007
.RJ Wrote:How can the treadmill offset forward thrust by spinning the wheels, when the wheels do not drive the forward motion of the plane?
CaptainHenreh Wrote:Angular momentum is imparted do them by the treadmill, some of which which will manifest itself as a linear backward force on the plane. Eventually, with enough acceleration by the treadmill the plane will *not* take off, as the linear force from the angular momentum of the wheels = the thrust force of the engines.
- .RJ - 12-20-2007
Evan Wrote:i think its the problem as stated that sucks and is unclear....
Thats part of the entertainment of reading these threads - the treadmill serves to confuse and obfuscate the 'problem' presented.
- Apoc - 12-20-2007
.RJ Wrote:Apoc Wrote:It won't fly. If the tradmill can offset the forward thrust
How can the treadmill offset forward thrust by spinning the wheels, when the wheels do not drive the forward motion of the plane?
Fuck my head hurts.
Okay it will fly... and as said before the wheels will be spinning at the rate of the forward motion of the plane and backward motion of the treadmill.
- Kaan - 12-20-2007
who has a treadmill, i'll be the RC plane.
- Ginger - 12-20-2007
Kaan Wrote:put a plane with no thrust on the treadmill, does it move forward? stand still? or move backward?
Put your face on one, what happens?
It's irrelevant to the conversation.
On the same token, the forward thrust generated by the jets far and away negates any friction-related force (what is ocurring in your example) that would cause the plane to go backwards.
If you wanted to quantify the force, it would be something like 100 newtons forcing the plane backwards, and 100,000,000 pushing it forwards. Given that the greater force isn't using the ground as it's opposing medium - which one is going to win-out and cause the plane to move.
- Evan - 12-20-2007
WRXtranceformed Wrote:It would be like putting a Corvette ZR1 on a lake of ice. You could mash the go pedal as much as you want, all you're going to get is a ton of exhaust gas and some melted ice.
to use your ice example.
you are standing on a frozen lake. you cant walk anywhere because its slippery. your shoes just slip. (Effectively the same as a treadmill - forward motion is negated with equal opposite force, in this case 0-0 = 0 instead of x-x = 0)
there is a branch hanging down from a tree.
you grab the branch and push.
what happens?
you go sailing across the lake.
treebranch = air = what the plane uses to propel itself.
- Ginger - 12-20-2007
Kaan Wrote:who has a treadmill, i'll be the RC plane.
That "experiment" won't work. The length of the treadmill is super relevant to the discussion.
- WRXtranceformed - 12-20-2007
Yeah I didn't think my analogy was good :lol:
- Kaan - 12-20-2007
i'll get a little one.
- Maengelito - 12-20-2007
like i said, if the relative position of the plane changes, then it takes off. if the vector > 0, it takes off
- Evan - 12-20-2007
Maengelito Wrote:like i said, if the relative position of the plane changes, then it takes off. if the vector > 0, it takes offISAT in the fuckin' hizzouse!
- G.Irish - 12-20-2007
No matter where I have seen this thread topic, it never fails to get at least 10 posts in an hour. We're at 50 posts in 1.5 hours
- Ginger - 12-20-2007
Your plane is going to have to be 1/34 the length of the treadmill. Or smaller.
Good luck
- HAULN-SS - 12-20-2007
ok, queers. Every treadmill I've ever stood on operated whether or not I was there to push on it or not. You know, a motor turns the belt.
Obviously the plane flies if there is nothing there to turn the belt, same as you can push a hotwheels car along a floor, and it does indeed move to a position ahead of it's former position relatively.
Isn't the question whether the plane flies, given the treadmill motor can turn infinitely fast, thus making the runway move infinitely fast backwards, thus keeping the plane stationary, and on the ground.
- Kaan - 12-20-2007
damn the real small planes dont have any wheels... at least that means it doesnt take much lift for them to stay off the ground.
- Ginger - 12-20-2007
HAULN-SS Wrote:Isn't the question whether the plane flies, given the treadmill motor can turn infinitely fast, thus making the runway move infinitely fast backwards, thus keeping the plane stationary, and on the ground.
That's only relevant as far as the frictional relationship between the plane's wheels body are concerned. A relationship which is negligable, at best. The plane will take off. The treadmill, realistically, can't turn fast enough for the Rex's angular momentum factor to matter.
In the case of the example, the fact that the treadmill is moving is irrelevant.
- HAULN-SS - 12-20-2007
Bingo - the friction is negligible. The wheels turn as fast as the treadmill motor, which is infinitely fast. The plane stays perfectly still, relative to everything else in the world, except for the treadmill belt. Thus no air moves over the wings of the airplane. No lift, no takeoff.
- Ginger - 12-20-2007
HAULN-SS Wrote:Bingo - the friction is negligible. The wheels turn as fast as the treadmill motor, which is infinitely fast. The plane stays perfectly still, relative to everything else in the world, except for the treadmill belt. Thus no air moves over the wings of the airplane. No lift, no takeoff.
UGH - haven't we been over this?
The WHEELS don't propel the body of the plane. The thrusters push against the AIR, which moves the plane.
It will take off.
- HAULN-SS - 12-20-2007
Look..I KNOW the thrusters push against the air. That's not the point. The point is that the plane has to have some sort of forward relative motion. If you put a hotwheels car on the treadmill, and use your finger to push it forward, but all the harder you push, the treadmill speed is also increased. The car NEVER moves forward on the treadmill. If it started out 2 feet from the front of the treadmill, no matter what, it will still be 2 feet from the front of the treadmill. The wheels aren't propelling the car - your finger is, and you're not a part of the treadmill system. With no forward motion, the plane can't fly.
- Ginger - 12-20-2007
You're a retard.
Put your finger BEHIND the car and push it forward. It'll go FORWARD relative to everything. This has been beated to death, if you really can't get it, to steal a phrase, I feel for the future.