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Old 12-08-2006, 03:41 PM   #81
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Originally Posted by Joe Perez View Post

For another, you're overlooking how airplane engines work, be they prop or jet.
I disagree. I really don't know how I can put it any more plainly (no pun intended). Have an open mind, re-read my previous statements/questions.

Again, airflow through the engines is completely different from airflow over the wings. One generates thrust, the other lift. There can only be thrust on the treadmill. Lift requires speed relative to the ground.

I didn't go through ground school for nothing.
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Old 12-08-2006, 03:42 PM   #82
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THE MOTHERFUCKING WHEELS ARE FREE SPINNING
It doesn't matter what the wheels are doing at all, regardless of the size of the text.
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Old 12-08-2006, 03:43 PM   #83
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Koto, you're barking up the wrong tree correctly

You are right, but we looked at the teaser the "wrong" way.
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Old 12-08-2006, 03:44 PM   #84
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It doesn't matter what the wheels are doing at all, regardless of the size of the text.
you're right, it doesn't. because the airplane propels itself through a BODY OF AIR regardless of how fast or slow the wheels spin.

I'd go into a long discussion using an example of an airplane on a carrier moving into or with the wind but it would be lost.
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Old 12-08-2006, 03:44 PM   #85
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I guess I'm just reading too much into it?

Good to know someone else has his thinking cap on though.
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Old 12-08-2006, 03:45 PM   #86
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Originally Posted by kotomile View Post
I guess I'm just reading too much into it?

Good to know someone else has his thinking cap on though.
ironically.....
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Old 12-08-2006, 03:46 PM   #87
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Quote:
Originally Posted by Philip View Post
you're right, it doesn't. because the airplane propels itself through a BODY OF AIR regardless of how fast or slow the wheels spin.

I'd go into a long discussion using an example of an airplane on a carrier moving into or with the wind but it would be lost.
If it was on a moving carrier, that's just it, the carrier is moving.
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Old 12-08-2006, 03:47 PM   #88
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Quote:
Originally Posted by kotomile View Post
If it was on a moving carrier, that's just it, the carrier is moving.
which coincidentally illustrates the fact that it's airspeed and angle of attack that matters, not the speed the wheels spin.

I can explain it six ways to sunday and you won't change your mind so why am I going to bother?
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Old 12-08-2006, 03:55 PM   #89
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I'm out... either people are reading the question entirely different, or they don't understand physics.
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Old 12-08-2006, 03:56 PM   #90
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The more you reply to me the more it seems we're thinking the same way..

I've been saying the speed the wheels are spinning doesn't matter, so it would appear we agree then.
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Old 12-08-2006, 03:57 PM   #91
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I'm out too, I think people are reading the question differently.
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Old 12-08-2006, 03:59 PM   #92
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bottom line is it takes off.
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Old 12-08-2006, 04:00 PM   #93
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Quote:
Originally Posted by kotomile View Post
Again, airflow through the engines is completely different from airflow over the wings. One generates thrust, the other lift. There can only be thrust on the treadmill. Lift requires speed relative to the ground.
It is different, but the two are directly related.

Air moving through the engine causes the engine to generate thrust, thus causing the engine to move forward relative to the surrounding atmosphere. Since the engine is rigidly coupled to the wing, then the wing will also move forward with respect to the aurrounding atmosphere.

Lift does not require speed relative to the ground, it requires speed relative to the air. This is why all critical velocities (Vr, Vs, Vfe-x, Vne, etc) are always given in KIAS (knots indicated airspeed).

A Cessna 172, if I remember correctly, will rotate at around 60 KIAS, and experiance best climb at about 80 KIAS. So let's say that N6066R is sitting on the ramp, tied down loosely. A hurrinane begins to blow, and the airplane is oriented such that it is facing into the wind. When the wind speed reaches 60 knots, the airplane will rotate. By the time the wind gets up to 80, the airplane will be completely off the ground, doing it's very best to climb against the ropes.

In essence, it will by flying with zero groundspeed.

Which is totally irrelevant to the question, since the hypothetical airplane will in fact have both airspeed and groundspeed. Its groundspeed relative to the treadmill will be twice its groundspeed relative to the real ground, but it'll still be moving.

Again, the important part of the original puzzle, and the one that everyone seems to be overlooking, is that the treadmill speed is servo-locked to the speed of the aircraft relative to the stationary external reference, NOT whatever speed is necessary to keep the aircraft stationary.


It just occured to me that all those folks who have been accused of post-whoring to get up to 10 and be graned PM abilities should be eating this thread alive.
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Old 12-08-2006, 04:01 PM   #94
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This post is not directed at any member because of its' position in the thread.

I'm getting very nervous about the knowledge that seems to be available on a simple matter of 8th grade physics
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Old 12-08-2006, 04:01 PM   #95
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You're a bit high on the 172.
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Old 12-08-2006, 04:03 PM   #96
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Quote:
Originally Posted by kotomile View Post
If it was on a moving carrier, that's just it, the carrier is moving.
The plane and carrier move together. There would be no difference in Vcarrier and Vaircraft. This is a different situation.

If you were to explore this arguement, you'd also have to look at the fact that the earth is moving.
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Old 12-08-2006, 04:06 PM   #97
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Quote:
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You're a bit high on the 172.
Sorry, it's been a while. N6066R perished in Hurricane Charley.
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Old 12-08-2006, 04:07 PM   #98
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Originally Posted by Joe Perez View Post
Consider what would happen if, with the engine off, we start the treadmill rolling backwards at 5MPH and fix it at that speed. Since the airplane is not generating any thrust, it will remain stationary with regard to the treadmill, and thus begin to move backwards at 5MPH relative to the fixed point of reference.
If the wheels/bearings are capable of "freewheeling" about the aircraft, then the unpowered aircraft would remain stationary on the treadmill, relative to the fixed point of reference, as the wheels spin.

Your argument was otherwise convincing, but this is a contradiction.
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Old 12-08-2006, 04:09 PM   #99
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Quote:
Originally Posted by Ben View Post
If the wheels/bearings are capable of "freewheeling" about the aircraft, then the unpowered aircraft would remain stationary on the treadmill, relative to the fixed point of reference.
.
in the absence of friction, yes.
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Old 12-08-2006, 04:11 PM   #100
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I dont even see how these bitches take off without wheels:

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