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| Thread ID: 93430 | 2008-09-16 06:00:00 | Aircraft Taking off problem | Thomas01 (317) | PC World Chat |
| Post ID | Timestamp | Content | User | ||
| 705619 | 2008-09-16 08:49:00 | But the engine provides the forward energy, not the wheels. Precisely, and tonight should sort out the theory, even if the experiment is flawed, but the main problem is that a small proportion of members of this forum do not understand the principles of flight. It is really very very simple: Aerodynamics rule the principles of flight, and thrust (propellor or jet) is the added component for powered flight. Unless physically tied down to the surface of the earth, provided the wheels are free to rotate at any speed required, nothing in the wheel-ground interface can interfere with takeoff because all of the principles of flight including "forward thrust" and "lift" are exercised ABOVE the surface of the planet, though enhanced by "ground effect". The undercarriage is simply a passive device included to keep the pilot's arse from scraping on the ground. There's even movies around of light planes flying (or landing) backwards in relation to flying direction over the runway when headwinds exceed minimum flying or landing speed. The plane actually lands with negative ground speed. It is that simple, and the question posed is a brain teaser with a simple hook that catches out anybody who has difficulty understanding the principles of flight, or can't think logically and ignore irrelevancies. The majority of respondents to this thread are in agreement that the plane flies, a small minority think otherwise. None of them are pilots thank heavens. I did the stats about a year ago, go back and check. Cheers Billy 8-{) Yes, it was a short year wasn't it! :D |
Billy T (70) | ||
| 705620 | 2008-09-16 08:53:00 | Helicopters do not use aerodynamics - they use magic and Newton's Third Law. They ascend or hover due to throwing down large amounts of money - the bigger the helicopter, the more money you must throw down. For those unscientific sceptics who disbelieve this, try stopping the money and see how far the helicopter will go. Note: the money throwing habit is so ingrained in helicopters that frequently they consume vast funds without even leaving the hangar. An alternative theory is that they are so ugly the earth rejects them. |
R2x1 (4628) | ||
| 705621 | 2008-09-16 10:37:00 | ... provided the wheels are free to rotate at any speed required, ... In the original version of the question, the wheels were NOT free to rotate at any speed so your argument is invalid. |
decibel (11645) | ||
| 705622 | 2008-09-16 11:40:00 | In the original version of the question, the wheels were NOT free to rotate at any speed so your argument is invalid . Jeez you guys are impossible . Maybe ignorance really is bliss, or the stuff you are smoking has totally shut down your cognitive faculties . :confused: In the original version the wheels WERE free to rotate, at whatever speed required to match the forward motion of the PLANE, and in the original the conveyor was a passive device that did nothing but MATCH the wheel rotational speed exactly . But never mind all of that, so long as the wheels are free to rotate and are not braked, they are totally irrelevant to the outcome, they just keep the prop from hitting the ground and allow relatively frictionless forward movement so the plane takes off normally, as happened on TV tonight . Airspeed 80 knots forwards through the air and in relation to the ground, conveyor speed 80 knots in the opposite direction, wheel rotation equivalent to 160 knots, but the AIRSPEED of 80 knots lets plane take off, if it hadn't reached that AIRSPEED the wheels wouldn't be turning etc etc . . . . . ad nauseum . Consider this, if the plane didn't move forwards under propellor thrust, the wheels wouldn't turn and the "conveyor " would stand still . But, the wheels are not powered, therefore engine/propellor/aerodynamic thrust (in simple terms the prop is simply a rotating aerofoil or "wing") is the sole source of forward motive power and the plane is able to take off because its forward motion in relation to the air around it is uninhibited other than by aerodynamic or axle bearing losses, neither of which is significant in relation to the engine power . It doesn't make any difference how fast the wheels rotate under combined forward plane movement and reverse conveyor movement, they don't affect aerodynamics or propellor thrust, which cannot be countered by the "ground" except by minor friction and bearing losses . Man would never have got into space with you guys in charge! All you ever say is that it won't fly, but you never take the time to explain in physics and aerodynamic terms exactly why you believe it won't, and how the mythical conveyor is able to counter aerodynamically generated forward thrust which is totally unrelated to wheels or the ground surface . The principle of a moving airstrip was used by aircraft carriers to help planes take off easier before the steam catapult was created . They sailed at full speed in the takeoff direction, which reduced flight deck (runway) speed in relation to the aircraft airspeed in the interests of boosting airspeed over the deck and the plane's wings, which is what powered flight is all about . And yes, I know that is the opposite direction to the mythical conveyor, but it emphasises that airspeed is what counts, not what is going on under the wheels . Fortunately the majority agree that the plane obeys the laws of physics (as seen on TV) and not the contorted mental gymnastics of the minority . So long . . . . . . . . got a plane to catch :waughh: Billy 8-{) |
Billy T (70) | ||
| 705623 | 2008-09-16 12:09:00 | With enough thrust, anything can take off. | beeswax34 (63) | ||
| 705624 | 2008-09-16 12:33:00 | In the original version the wheels WERE free to rotate, at whatever speed required to match the forward motion of the PLANE, and in the original the conveyor was a passive device that did nothing but MATCH the wheel rotational speed exactly . Airspeed 80 knots forwards through the air and in relation to the ground, conveyor speed 80 knots in the opposite direction, wheel rotation equivalent to 160 knots, but the AIRSPEED of 80 knots lets plane take off, if it hadn't reached that AIRSPEED the wheels wouldn't be turning etc etc . . . . . ad nauseum . LOL WUT . If the conveyor speed matches the wheel rotational speed exactly, as you have said, then why have you used different numbers in your example? You've made the conveyor match the airspeed rather than the wheel rotational speed . The conveyor should be going backwards at 160 knots, not 80 . However, this causes the wheels to be spinning faster, meaning the conveyor should be going faster . And so on . You're wrong, ***** . |
roddy_boy (4115) | ||
| 705625 | 2008-09-16 13:09:00 | With enough thrust, anything can take off. My point excactly in the original thread. A harrier jump jet is equipped with wheels. Wheel rotation speed seems to be not important when it comes to take off. The harrier flies as it has thrust. |
Sweep (90) | ||
| 705626 | 2008-09-16 19:22:00 | Would Roddy explain why he thought last nights demo was so flawed? As I see he often makes statements with nothing to actually back them up. | gary67 (56) | ||
| 705627 | 2008-09-16 21:27:00 | Lets say we put a runway on the equator facing east west. The earth is spinning at the equator at about 6,000 mph from east to west. We put a plane on the western end of the runway facing east, now well the plane take off. This is the same as putting a plane on a conveyor belt. You all know the answer to this. :) |
Trev (427) | ||
| 705628 | 2008-09-16 21:38:00 | Oh Dear. I feel I should apologise for starting this argument up again. I really didn't expect so many responses. It still amazes me that so many people think that the plane will not take off. Perhaps my training as an design engineer (in the aircraft industry) enables me to view the problem logically. But in the program itself the pilot chosen to fly the plane himself didn't think the plane could take off. He was a very surprised person when it left terra firma without any problems. What else could it do? Tom |
Thomas01 (317) | ||
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