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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 | ||
| 410072 | 2005-12-05 09:18:00 | God you always have to be the pompous asshat don't you . The answer has been re hashed a stack of times in this thread, many of them by you . God you always have to be the arrogant asshat don't you . You have posted non-answers to so many threads just to show off your acerbic wit that you have become a legend in your own tiny mind . :groan: You will need many moar jiggahurtz than you could ever possess my rage-ridden friend . And you will never fly, as I pointed out to you once before . Cheers Billy 8-{) P . S . I love you too . :D |
Billy T (70) | ||
| 410073 | 2005-12-05 09:25:00 | :lol: you're great. I bet the family loves you at parties. | ninja (1671) | ||
| 410074 | 2005-12-05 09:40:00 | The situation is similar to if the plane's wheels were imbedded in concrete. They're gonna be stuck in the same place, whether they're on the conveyor or whether stuck to the ground. They'll keep the plane rooted to the spot. This plane ain't going anywhere! Greg - if you can't understand it just accept it. Even Jack has finally caught on. As he says with the plane sitting on the conveyor with the conveyor moving very slowly and the engines stopped the plane will move back at the speed of the conveyor. If the engines are started and enough power supplied to hold the plane stationary (it won't need very much as you only need to overcome the friction on the wheel bearings, idle power most likely) the plane will stay in one place with the wheels spinning at the speed of the conveyor. Now increase the speed of the conveyor to say 100mph the plane will still stay in the same spot with the wheels spinning at the speed of the conveyor with no change in engine power as the wheel friction has not changed and the only change is the wheels spinning faster. Now increase the engine power to takeoff thrust the plane moves along the conveyor, it has to as that is what happens every takeoff regardless what surface it is on and there is nothing to stop it accelerating and the airspeed increases and it will takeoff. As mentioned the wheels will be spinning exceptionally fast but that is not relevant. This is a slightly different spin on the problem but if you can get this principle then the rest will come clear. |
Safari (3993) | ||
| 410075 | 2005-12-05 09:43:00 | God you always have to be the arrogant asshat don't you.One day Billy you'll rent an original thought. | Greg (193) | ||
| 410076 | 2005-12-05 09:44:00 | The situation is similar to if the plane's wheels were imbedded in concrete . They're gonna be stuck in the same place, whether they're on the conveyor or whether stuck to the ground . They'll keep the plane rooted to the spot . This plane ain't going anywhere! You have to get past your fixation with wheels . Consider a plane on ordinary tarmac, then draw a horizontal line across the wheel hubs . Now consider both sides of the line separately . Above the line, the laws of aerodynamics apply and if the engines are throttled up, thrust will be generate and the fuselage will try to go forwards . If the brakes are on it will not move unitl thrust overcomes braking power . But in this example the brakes are off, so it will accelerate forward and gain airspeed until it lifts off . Now consider below the line . If the brakes are on, the wheels do not move in relation to the tarmac . Now let the brakes off (which is what the question suggests) . The wheels will roll along the surface of the tarmac and the plane will accelerate forward and take off . Now imagine the tarmac starting to roll backwards at a speed proportional to the forward rolling speed of the plane (which is what this question postulates) . The wheels will rotate at twice the effective ground speed (in relation to a fixed point off the runway), but the plane will continue to accelerate and will reach flying speed and take off because above the axle line its behaviour is dictated by the laws of aerodynamics and the thrust of the engines, and the wheels are free to rotate at any speed they can mechanically cope with . When the plane reaches a forward AIR SPEED of 100 knots with respect to the fixed point, the tarmac will be receding at 100 knots with respect to the same fixed point, but the effective rotational speed of the wheels will be 200 knots . However, above the axle line the aircraft will be responding to the laws of aerodynamics and will lift off and fly away, giving its wheels a rest until next time . In the event that the drag of tires and poorly lubricated wheel bearings is such that the engine(s) are not quite developing enough power to reach flying speed, the pilot will advance the throttles and feed the engines moar jiggahurtz, after which it will develop the necessary airspeed and sail off into the sunset . Elementary my dear Watson . Just don't read more into the question than was there to start with . Cheers Billy 8-{) |
Billy T (70) | ||
| 410077 | 2005-12-05 09:48:00 | Jet engines at full thrust vs Conveyor belt no contest. The engines would likely rip up the conveyor belt. The Plane will Fly. |
wmoore (6009) | ||
| 410078 | 2005-12-05 10:00:00 | Greg - if you can't understand it just accept it . Even Jack has finally caught on . As he says with the plane sitting on the conveyor with the conveyor moving very slowly and the engines stopped the plane will move back at the speed of the conveyor . If the engines are started and enough power supplied to hold the plane stationary (it won't need very much as you only need to overcome the friction on the wheel bearings, idle power most likely) the plane will stay in one place with the wheels spinning at the speed of the conveyor . Now increase the speed of the conveyor to say 100mph the plane will still stay in the same spot with the wheels spinning at the speed of the conveyor with no change in engine power as the wheel friction has not changed and the only change is the wheels spinning faster . Now increase the engine power to takeoff thrust the plane moves along the conveyor, it has to as that is what happens every takeoff regardless what surface it is on and there is nothing to stop it accelerating and the airspeed increases and it will takeoff . As mentioned the wheels will be spinning exceptionally fast but that is not relevant . This is a slightly different spin on the problem but if you can get this principle then the rest will come clear . Ok, more blah blah blah . Wonder why some folks go to such lengths to provide such inane reasoning? :confused: Think about it . . . *wheels don't move forward *wheels attached to plane *ergo, plane doesn't move forward Therefore, no forward motion, and no flight . |
Greg (193) | ||
| 410079 | 2005-12-05 10:03:00 | I can see both sides of the argument (assuming such a conveyor could exist) but as far as compelling evidence goes, I'd say the fan on the skateboard mounted on a moving sheet of paper answers the question. It doesn't get any more scientific than that..... :D | andrew93 (249) | ||
| 410080 | 2005-12-05 10:05:00 | Jet engines at full thrust vs Conveyor belt no contest. The engines would likely rip up the conveyor belt. The Plane will Fly.It's a hypothetical situation mate - too many people aren't getting the essence of the problem. If people can't understand the question properly they really shouldn't debate the answer. |
Greg (193) | ||
| 410081 | 2005-12-05 10:10:00 | There are 2 answers. IF there is non-infinite friction between the tyres and the conveyer belt, the plane will fly. IF infinite friction is assumed, the wheels will spin on the conveyer belt and hold the plane back. As Greg says, it's a hypothetical situation. |
roddy_boy (4115) | ||
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