Something to think about

[michal 44]

>What ground? How about the trees along the runway?Michael J.http://www.precisionmanuals.com/images/forum/pmdg_744F.jpghttp://www.hifisim.com/images/asv_beta_member.jpg

[michal 44]

>Will the race car fly? No, of course not. Why? What makes>the car different from the plane? Wings. Put in your race car a jet engine and it will be able to accelerate forward no matter what treadmill does. If you don't understand the basics of Newtonian mechanis and how jet/rocket engine is fundamentally different from your car engine then it is pointless to argue anymore.Michael J.http://www.precisionmanuals.com/images/forum/pmdg_744F.jpghttp://www.hifisim.com/images/asv_beta_member.jpg

[kerosene31 349]

>For one you fail to identify that the main difference between>a car and a plane in our example is not wings, but the fact>that the plane does not have wheel drive and it is therefore>indifferent about the speed of the threadmill. That is why a>car will stand still while a plane will accelerate.>>-

[kerosene31 349]

>>Will the race car fly? No, of course not. Why? What>makes>>the car different from the plane? Wings. >>Put in your race car a jet engine and it will be able to>accelerate forward no matter what treadmill does. If you don't>understand the basics of Newtonian mechanis and how jet/rocket>engine is fundamentally different from your car engine then it>is pointless to argue anymore.>So, if I put a jet engine on my car, it will fly? That truck they put the rocket on at airshows flies? I think we're arguing about two different things at this point.

[Guest oyvindhansen]

And if you read the avveb article it concludes that the aircraft will take off fine, and the only ones who thought it wouldn't are people who think the aircraft has to push agaist the runway to gain speed, strangely the same people who have no physics or engineering background.-

[Guest Adverse Yawn]

Kero,>>http://www.avweb.com/news/columns/191034-1.htmlYour a confusing fellow. You post a link that say you are wrong :)

[kerosene31 349]

I guess I am just totally confused. The avweb article eventually says that the plane will fly? So the aircraft would fly straight up? With no air moving over the wings?

[victorwest2 0]

As I've said before, the only way I can see the aircraft taking off is if the thrust of the engines is large enough to counteract the reverse flow of the treadmill. It has already been stated in the first post that the aircraft, for the purposes of the question, CANNOT exceed the speed of the treadmill. If it were to do so the experiment would be invalid. If the aircraft cannot exceed the speed of the treadmill then I agree the IAS would be zero as there would be no air flow for an IAS to be registered and therefore the treadmill would also remain stationary. However, the question does not mention IAS. It just says "the forward speed of your aircraft". Now what exactly is forward speed. If you use IAS that may not necessarily be correct. In a strong headwind the IAS would not be the same as the speed perceived by either the pilot or an observer. I would have thought that for most people the "forward speed" of the aircraft would not be the IAS but the speed relative to the surrounding area. If use the observed speed as the "forward speed" then it is perfectly possible, I believe, for the plane to remain stationary on a moving treadmill.

[Guest enave]

>So, if I put a jet engine on my car, it will fly? Here is what he said:"Put in your race car a jet engine and it will be able to accelerate forward no matter what treadmill does. If you don't understand the basics of Newtonian mechanis and how jet/rocket engine is fundamentally different from your car engine then it is pointless to argue anymore."Please quote any part of his statement that says or implies that the car will fly.HE DID NOT SAY THAT THE CAR WILL FLY! HE SAID IT WOULD MOVE!If you put wings on it, along with the jet engine, THEN it could fly.jeez. May I ask how old you are?

[Guest oyvindhansen]

>As I've said before, the only way I can see the aircraft>taking off is if the thrust of the engines is large enough to>counteract the reverse flow of the treadmill.Imagine yourself rolleskating on a threadmill with a rocket engine on your back. You think the rollerskates will hold you in place just because the threadmill moves backwards?-

[kerosene31 349]

Ok, I get it (I think)I'm saying it won't fly *assuming* the plane can get zero forward motion relative to the ground outside of the treadmill. Others are arguing that the thrust of the plane will pull it forward, and therefore generate lift. The whole point is that this magic treadmill does not exist, and the thrust would eventually win out. Right?

[Guest oyvindhansen]

Getting closer. Now, if you could convince the others...-

[victorwest2 0]

>>As I've said before, the only way I can see the aircraft>>taking off is if the thrust of the engines is large enough>to>>counteract the reverse flow of the treadmill.>>Imagine yourself rolleskating on a threadmill with a rocket>engine on your back. You think the rollerskates will hold you>in place just because the threadmill moves backwards?>>-

[kerosene31 349]

So, back to the rollerskate and rocket example. We strap a rocket (making sure it stays perfectly horizontal) onto a person with rollerskates. (lets ignore the friction of the wheels)Now, lets say that the rocket will push the person exactly 200 mph. So, if we had a big treadmill which would move in 200 mph the opposite direction, the person would still go forward? This is where the real question lies.

[Guest oyvindhansen]

>No, of course it wouldn't. But that is not what the question>states. It says the treadmill will match the forward speed of>your plane.But the threadmill has no way of affecting the movement of the aircraft, because the aircraft doesn't use ground friction for its acceleration.-