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| Thread ID: 64128 | 2005-12-04 07:01:00 | Sunday night Brain Bender - Airplane Physics | miknz (3731) | PC World Chat |
| Post ID | Timestamp | Content | User | ||
| 409992 | 2005-12-04 18:43:00 | The thinking exhibited by many here is woolly in the extreme. I concede drcspy, I didn't fully say what I had in mind about the conveyor passing underneath the plane. What I meant was that if wheel bearing friction was zero then the conveyor could pass under the plane without the plane moving, and assuming no engine thrust. This was to emphasise the two important fundamental principles involved here: 1) the only mechanical coupling between the plane and the moving runway is by way of wheel bearing friction. 2) Lift is provided by motion of the plane through the stationary air, as drcspy says,air that is still relative to earth, not relative to the moving runway. Now it doesn't matter one jot to a first order approximation which direction the runway moves, either with the plane or opposed to the plane. The runway will drag air with it though, a thin layer determined by boundary layer theory. Anyone who thinks the moving runway carries the whole atmosphere above it along with it and thus affects air flow over the wings has no brains at all, sorry Jack, that means you as well as others of the same ilk. The boundary layer of air dragged along with the moving runway, depending on the direction of movement will either enhance, or decrease ground effect, but this is second order, and not really within the scope of the simple question. |
Terry Porritt (14) | ||
| 409993 | 2005-12-04 19:01:00 | question is the plane moving forward relative to some fixed point ? |
drcspy (146) | ||
| 409994 | 2005-12-04 19:17:00 | I don’t believe I’m doing this but here goes . :rolleyes: Lets forget all the peripherals like wheel bearing friction boundary layer drag etc etc A plane relies on the prop dragging it along fast enough for the air over the wings to lift it off . Thus we have flight . It does not rely on wheel traction . (And don’t anyone bother to tell me it was a jet plane) :D |
B.M. (505) | ||
| 409995 | 2005-12-04 19:23:00 | drcspy, the plane will be moving forward as soon as the propeller gets sufficient grip on the air. ;) | B.M. (505) | ||
| 409996 | 2005-12-04 19:29:00 | :o :o | JJJJJ (528) | ||
| 409997 | 2005-12-04 19:35:00 | A Harrier Jet yes or a helicopter. A normal plane will sit there all day, going nowhere. All you have is a stationary plane, thats it. The revolving wheels may as well be tank tracks, all they do is allow a plane to move forward on the ground. |
Veale (536) | ||
| 409998 | 2005-12-04 19:40:00 | i repeat................. s the plane moving forward relative to some fixed point ? because if it's not then it WONT take off...... |
drcspy (146) | ||
| 409999 | 2005-12-04 20:05:00 | Lol internets. | ninja (1671) | ||
| 410000 | 2005-12-04 20:05:00 | The wheels would not be turning. They would be sliding. Equal force in both directions Sorry Jack, mind out for the Koalas, you are so far up a gum tree you are unlikely to see terra-firma again. Why on earth do you think that the wheels won't rotate? They are not driven, they free-wheel. How do you think cyclists ride on rollers indoors for training, or dynamometers test the power output at the wheels of a car or motorcycle? They are all different views of the same basic principle, except in thoise examples the motive force is applied to the wheels. I needn't explain to an old flight-sim hand like you how planes fly, but I will, the motive force comes from the propellors or jet thrust, not the wheels. Cheers Billy 8-{) |
Billy T (70) | ||
| 410001 | 2005-12-04 20:21:00 | ..but will the number of "It won't fly people" drop off like the article to avweb post by Safari says ;) The question is not clearly worded, however, but then again it has a "mystical" conveyor belt. After achieving lift, the plane will move forward relative to a fixed point. |
gibler (49) | ||
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