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Melkor Bloodaxe
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Posted - 2006.07.11 10:07:00 -
[31]
Originally by: Kalaan Oratay Ah yea, I think I got it.
At first I thought your rollerblade analogy was flawed, in that if you were to just stand on a treadmill and not hold on to anything, you would probably just fall off the back of it, as you wouldnt be able to overcome your own momentum. However, holding onto a rail to overcome the initial push would get you rolling, at which point you can just let go and you'd continue to roll (no net speed change). If you wanted to change speed, you just grabbed the rail again and pushed/pulled.
Now consider the situation with the plane on the treadmill. The rail would be the air, and the engine to be the rollerbladers arm. I think that works.
That sort of clears it up in my head. Nice question (god I hope I got it )
I think you got it indeed. It was indeed a nice question. Helped me through the morning ---
Originally by: HippoKing Since when is justified killing more fun than random killing?
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Melkor Bloodaxe
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Posted - 2006.07.11 10:08:00 -
[32]
Originally by: Rodj Blake If the treadmill's speed cancels out the thrust from the engines, then the relative speed of the air going around the wings will be zero.
So no lift, and no take-off
The treadmill's speed doesn't cancel out the thrust from the engines. that's the tricky bit of the story... ---
Originally by: HippoKing Since when is justified killing more fun than random killing?
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Kayl Breinhar
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Posted - 2006.07.11 10:18:00 -
[33]
Edited by: Kayl Breinhar on 11/07/2006 10:19:34 Airplane on a treadmill with no headwind = plane going nowhere but keeping pace with the treadmill.
Airplane on a treadmill with a decent headwind = plane SLOWLY going *some*where provided we're not talking about a 747-400.
This argument has several holes in it.
1. Is the treadmill independently powered or passively driven by the thrust the airplane provides? If it's the latter, then with no headwind the plane is going to be driving the speed of the treadmill. If it's the former, then it's all in the headwind to add the rest.
2. Is there a sufficient headwind to provide additive lift to the wings? If not, you're working with isometrics - one hand pushing against the other.
3. How much does the plane WEIGH? If it's a kitplane supporting one man and the minimum amount of fuel possible for a short flight, then it's more feasible than a 747 trying to do the same thing since a 20 knot headwind might provide sufficient lift over an ultralight frame to help get it off the ground.
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Melkor Bloodaxe
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Posted - 2006.07.11 10:26:00 -
[34]
Originally by: Kayl Breinhar Edited by: Kayl Breinhar on 11/07/2006 10:19:34 Airplane on a treadmill with no headwind = plane going nowhere but keeping pace with the treadmill.
Airplane on a treadmill with a decent headwind = plane SLOWLY going *some*where provided we're not talking about a 747-400.
This argument has several holes in it.
1. Is the treadmill independently powered or passively driven by the thrust the airplane provides? If it's the latter, then with no headwind the plane is going to be driving the speed of the treadmill. If it's the former, then it's all in the headwind to add the rest.
The mill has same speed as the plane, powering has no effect
Quote:
2. Is there a sufficient headwind to provide additive lift to the wings? If not, you're working with isometrics - one hand pushing against the other.
headwind is provided by the forward motion of the plane
Quote:
3. How much does the plane WEIGH? If it's a kitplane supporting one man and the minimum amount of fuel possible for a short flight, then it's more feasible than a 747 trying to do the same thing since a 20 knot headwind might provide sufficient lift over an ultralight frame to help get it off the ground.
Weight has nothing to do with this.
---
Originally by: HippoKing Since when is justified killing more fun than random killing?
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Wild Rho
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Posted - 2006.07.11 10:32:00 -
[35]
Originally by: Rodj Blake If the treadmill's speed cancels out the thrust from the engines, then the relative speed of the air going around the wings will be zero.
So no lift, and no take-off
That caught me out at first now I realised I made a simple mistake. You're thinking of the aircrafts thrust being canceled out by the treadmill in the same way the "thrust" generated by a cars engine would be canceled out by the treadmill.
With a car the engine is connected to the wheels and so that's why the treadmill would cancel it out.
However with an aircraft the engines are completely seperate from the wheels and will push the aircraft forward regardless of what the wheels are doing. If the treadmill was to move at the same speed as the aircraft in the opposite direction the only difference would be its wheels would turn twice as fast. The aircraft would continue to move forward regardless.
WE ARE DYSLEXIC OF BORG. Refutance is systile. Your ass will be laminated. - Jennie Marlboro
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PKlavins
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Posted - 2006.07.11 10:44:00 -
[36]
Sure the plane can take off, just turn the nose to face the direction of the treadmill and WHOOSH, all gone
apart from that, how does the treadmill know what speed to turn at, since the plane's speed isn't constant? I make sigs/banners 5mill each, convo/evemail for details
PATENTED mod-hack-proof sig! [orange]Sig file must be under 24000 bytes, yours is currently 25038, please resize - Cathat |
Grimpak
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Posted - 2006.07.11 11:04:00 -
[37]
Edited by: Grimpak on 11/07/2006 11:06:59
Originally by: Melkor Bloodaxe
Originally by: Rodj Blake If the treadmill's speed cancels out the thrust from the engines, then the relative speed of the air going around the wings will be zero.
So no lift, and no take-off
The treadmill's speed doesn't cancel out the thrust from the engines. that's the tricky bit of the story...
yes but if the thrust cancels the threadmill backward momentum the airplane will remain in the same spot, wich is observable if you are watching out of the threadmill. and if you are in the same spot, the airplane can't get enough air in the wings (zero movement), thus it can't fly.
basic physics where the backward movement nullifies the forward movement (thus forward movement = zero), and basic aeronautic engeneering where the principle of the airplane, whether is it by jet, or even by the older propeller engine (propeller MIGHT get some air in the wings), where you need air to be moving in the wings for them to work. Jets only purpose in the airplanes is to propell them forward, thus aquiring air sustentation (sp?) in the wings wich is the principle that every airplaine works.
...however a jet CAN liftoff from a threadmill going in opposite direction IF there are conditions for it. And by conditions I mean enough wind strength that provides enough air in the wings, thus lifting the airplane enough to be free of the threadmill, thus making the jet engines propell the airplane forward, wich, in turn, will make even more air cross the wings.
however if the air movement is zero, this won't happen. -------
Originally by: Abdalion
Originally by: Jebidus Skari What, in EVE, is a Tyrant?
Me. Especially when it comes to troll threads.
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Melkor Bloodaxe
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Posted - 2006.07.11 11:24:00 -
[38]
Edited by: Melkor Bloodaxe on 11/07/2006 11:24:24
Originally by: Grimpak a lot of stuff
We all agree that a car wouldn't move anywhere if the treadmill had the same speed as the car, right? That is, because the engines drive the wheels and the speed is derived from the turning of the wheels. Agree?
Now place an aircraft on the treadmill. Throttle up, the speed indicator starts climbing, and thus the treadmill will start to turn in opposite direction with the same speed as the aircraft. However, the aircraft will still move forward, because the groundspeed has nothing to do with the actual speed of the aircraft. The speed of the aircraft is derived from the forward motion with help of the airflow across the plane (pitot tube). Groundspeed also has nothing to do with airflow over/under the wings. Actually groundspeed is not important at all for an airplane. ---
Originally by: HippoKing Since when is justified killing more fun than random killing?
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Crumplecorn
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Posted - 2006.07.11 11:36:00 -
[39]
I SAID IT WAS A TRICK QUESTION!!!!one I even put a question mark after my 'no' when I got first. OP is a bastard (), but I <3 this question.
Anyone who now says the aircraft won't take off, don't bother posting, you don't get it even after its explained, you have failed, move along. ----------
Always Up To SomethingÖ |
Melkor Bloodaxe
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Posted - 2006.07.11 12:15:00 -
[40]
Originally by: RedClaws
Originally by: Crumplecorn
Originally by: RedClaws to people saying its possible for a plane to take off that way: why the heck aren't we using it yet then? It would drasticly reduce the need for runway lengths.
Plane needs wind in the wings to take off, you get that by moving into the wind , since this plane is standing still you don't get any wind in the wings and it won't go up.
Easy as that... seriously wth are you ppl on about?
The plane is not standing still as there is no backward force or movement
What the? ofcourse its standing still : the threadmill is keeping it in the same position isn't it?
Nope. the treadmill is moving in the opposite direction of the airplane. doesn't state that the airplane stands still. ---
Originally by: HippoKing Since when is justified killing more fun than random killing?
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RedClaws
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Posted - 2006.07.11 12:16:00 -
[41]
Yah i just got the same idea after posting.
So it would be a very inefficiant way of moving. Heh strange but i'd like to see some proof aswell
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Rodj Blake
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Posted - 2006.07.11 12:16:00 -
[42]
If the conveyor belt moves backwards, and the plane's engines are off, what happens?
Dulce et decorum est, pro imperator mori |
D'onryu Shoqui
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Posted - 2006.07.11 12:17:00 -
[43]
Originally by: Crumplecorn
Originally by: D'onryu Shoqui Edited by: D''onryu Shoqui on 11/07/2006 11:58:32 its its a commerical airliner that is huge and weights alot if probably isnt going to get enough speed because of all the wait on the wheels glueing in to the treadmill.
If the plane's weight was enough to stop the wheels turning it could never take off
i did not say the wheels would not spin, i meant the force pushing down on the wheels is probably to great and the plane would just roll backwords if nothing is stopping it from moving. stick a really fat person on a treadmill wearing rollerblades and tell us if the wheels move without any force keeping him from moving backwords
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Crumplecorn
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Posted - 2006.07.11 12:21:00 -
[44]
Edited by: Crumplecorn on 11/07/2006 12:24:45
Originally by: Rodj Blake If the conveyor belt moves backwards, and the plane's engines are off, what happens?
Since the belt matches the planes speed, the belt stops But I know what you mean, the plane would end up going backwards over a long enough time. But the engines would way way way overcome this.
If the belt does the same speed as the plane, then the wheels are doing twice the speed of the plane. Hence, if the aircraft cannot take off in this scenario, it means the engines cannot overcome the friction of the wheels at twice the takeoff speed of the plane. Watch a jet airliner taking off and tell me it couldn't quite happily keep accelerating given a long enough runway ----------
Always Up To SomethingÖ |
Melkor Bloodaxe
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Posted - 2006.07.11 12:22:00 -
[45]
Edited by: Melkor Bloodaxe on 11/07/2006 12:25:35
Originally by: Rodj Blake If the conveyor belt moves backwards, and the plane's engines are off, what happens?
With no drag in the wheel bearings the plane would not move. Because of the drag the plane would start moving backwards very slowly, gathering speed on the way.
I'm glad everyone is with us now, that the airplane WILL take off
---
Originally by: HippoKing Since when is justified killing more fun than random killing?
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Crumplecorn
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Posted - 2006.07.11 12:27:00 -
[46]
******* excellent question. Will be asking a lot of people that one! ----------
Always Up To SomethingÖ |
Melkor Bloodaxe
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Posted - 2006.07.11 12:31:00 -
[47]
Edited by: Melkor Bloodaxe on 11/07/2006 12:31:08
Originally by: Crumplecorn ******* excellent question. Will be asking a lot of people that one!
Yeah, really was. Fooled me in the beginning. Think I'll post it on the message board at work. They're are all aeronautics teachers here ---
Originally by: HippoKing Since when is justified killing more fun than random killing?
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Rodj Blake
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Posted - 2006.07.11 12:38:00 -
[48]
Originally by: Melkor Bloodaxe Edited by: Melkor Bloodaxe on 11/07/2006 12:25:35
Originally by: Rodj Blake If the conveyor belt moves backwards, and the plane's engines are off, what happens?
With no drag in the wheel bearings the plane would not move. Because of the drag the plane would start moving backwards very slowly, gathering speed on the way.
I'm glad everyone is with us now, that the airplane WILL take off
The no-drag condition was not mentioned in the initial problem.
There will be drag, because the weight of the plane will cause friction between the conveyor and the tyres.
Dulce et decorum est, pro imperator mori |
Crumplecorn
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Posted - 2006.07.11 12:42:00 -
[49]
Originally by: Rodj Blake The no-drag condition was not mentioned in the initial problem.
There will be drag, because the weight of the plane will cause friction between the conveyor and the tyres.
No more than twice the drag the aircraft has to overcome when taking off from a runway, as I explained above. ----------
Always Up To SomethingÖ |
Grimpak
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Posted - 2006.07.11 12:46:00 -
[50]
Edited by: Grimpak on 11/07/2006 12:46:51
Originally by: Crumplecorn If the belt does the same speed as the plane, then the wheels are doing twice the speed of the plane. Hence, if the aircraft cannot take off in this scenario, it means the engines cannot overcome the friction of the wheels at twice the takeoff speed of the plane. Watch a jet airliner taking off and tell me it couldn't quite happily keep accelerating given a long enough runway
that's what I was trying to say if the airplane overcomes all sorts of backward movement that are implied (and I'm counting friction in the backward movement, not only the treadmill*), then he gets enough speed to liftoff.
anyways, does this means that people aggree that the airplane will liftoff if he manages to overcome the treadmill? I'm getting all confuzzled here already
*the treadmill backwards movement can be accounted as friction aswell -------
Originally by: Abdalion
Originally by: Jebidus Skari What, in EVE, is a Tyrant?
Me. Especially when it comes to troll threads.
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Kalaan Oratay
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Posted - 2006.07.11 12:51:00 -
[51]
African or European?
--- Originally by: Archilies Ignore what others say: Fit what you want, with what you have, whenever you want.
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Crumplecorn
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Posted - 2006.07.11 12:51:00 -
[52]
Originally by: Grimpak anyways, does this means that people aggree that the airplane will liftoff if he manages to overcome the treadmill? I'm getting all confuzzled here already
Not only that, but it will definitely overcome the treadmill, the wheels will simply not slow it down so much that it can't, unless maybe they're crap minmatar ones. ----------
Always Up To SomethingÖ |
Crumplecorn
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Posted - 2006.07.11 12:54:00 -
[53]
Originally by: Kalaan Oratay African or European?
? ----------
Always Up To SomethingÖ |
Melkor Bloodaxe
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Posted - 2006.07.11 12:56:00 -
[54]
Edited by: Melkor Bloodaxe on 11/07/2006 12:57:50
Originally by: Crumplecorn
Originally by: Grimpak anyways, does this means that people aggree that the airplane will liftoff if he manages to overcome the treadmill? I'm getting all confuzzled here already
Not only that, but it will definitely overcome the treadmill, the wheels will simply not slow it down so much that it can't, unless maybe they're crap minmatar ones.
Hey, we're not becoming personal now, are we? Besides, nothing beats our square tires
---
Originally by: HippoKing Since when is justified killing more fun than random killing?
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Crumplecorn
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Posted - 2006.07.11 12:57:00 -
[55]
Originally by: Melkor Bloodaxe
Originally by: Crumplecorn
Originally by: Grimpak anyways, does this means that people aggree that the airplane will liftoff if he manages to overcome the treadmill? I'm getting all confuzzled here already
Not only that, but it will definitely overcome the treadmill, the wheels will simply not slow it down so much that it can't, unless maybe they're crap minmatar ones.
Hey, we're not becoming personal now, are we?
I have nothing but the utmost respect for the minmatar and those junkpiles you fly. ----------
Always Up To SomethingÖ |
Melkor Bloodaxe
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Posted - 2006.07.11 12:57:00 -
[56]
Originally by: Crumplecorn
Originally by: Kalaan Oratay African or European?
?
Swallows I presume. But that doesn't have anything to do with this... ---
Originally by: HippoKing Since when is justified killing more fun than random killing?
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Crumplecorn
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Posted - 2006.07.11 12:58:00 -
[57]
Originally by: Melkor Bloodaxe
Originally by: Crumplecorn
Originally by: Kalaan Oratay African or European?
?
Swallows I presume. But that doesn't have anything to do with this...
If a swallow is on a treadmill and ...... ----------
Always Up To SomethingÖ |
Melkor Bloodaxe
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Posted - 2006.07.11 13:01:00 -
[58]
Originally by: Crumplecorn
Originally by: Melkor Bloodaxe
Originally by: Crumplecorn
Originally by: Kalaan Oratay African or European?
?
Swallows I presume. But that doesn't have anything to do with this...
If a swallow is on a treadmill and ......
Well, if we substitute the swallow in the same question and the aircraft was just about to take off that would be a bird-strike, with a lot of mess as result... ---
Originally by: HippoKing Since when is justified killing more fun than random killing?
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FooB2
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Posted - 2006.07.11 13:05:00 -
[59]
why not just get a remote control plane, and a normal treadmill and try it?
watch it take off. the wheels dont provide thrust, the engines do, which move the air, not the wheels. the wheels just roll along. therefore, given the assumption that the treadmill is long enough for the plane to get enough distance to get up to speed. the only difference is that the wheels will be revolving at twice the normal speed they would on a normal ground takeoff, assuming the wheels can take this kind of punishment, which for the sake of this argument can.
www.EVE-Gamers.co.uk - YOUR community for EVE Gaming |
Crumplecorn
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Posted - 2006.07.11 13:05:00 -
[60]
Originally by: Melkor Bloodaxe
Originally by: Crumplecorn
Originally by: Melkor Bloodaxe
Originally by: Crumplecorn
Originally by: Kalaan Oratay African or European?
?
Swallows I presume. But that doesn't have anything to do with this...
If a swallow is on a treadmill and ......
Well, if we substitute the swallow in the same question and the aircraft was just about to take off that would be a bird-strike, with a lot of mess as result...
If the plane is facing in the direction the treadmill is moving it will accelerate by itself and eventually take off without using engines at all. ----------
Always Up To SomethingÖ |
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