|
Post by RWChris on Jul 23, 2009 11:11:12 GMT
OK i've just thought about this properly whilst making a cuppa and have changed my mind. I think I misinterpreted what was being asked.
The aircraft will take off as long as the pilot applies enough power to allow it to happen. A small amount of power would have to be applied to keep the aircraft relatively stationary but once this has been applied (enough to overcome the frictional force of the wheels), the aircraft should remain stationary not matter how high the treadmill is turned up.
From this point on every application of extra thrust will start to move the aircraft forward until a point where it reaches the VLOF speed.
It doesn't make any difference if it were a propellor or jet aircraft incase anybody was wondering.
|
|
|
Post by edinburghstokie on Jul 23, 2009 11:27:19 GMT
Excellent RWChris. As I said before, the structure of the question is designed to confuse the issue. By the way, do all traniee pilots go to NZ? I have a friend here who has a boyfriend over there too for pilot training.
|
|
|
Post by thepremierbanksy on Jul 23, 2009 11:34:10 GMT
Has anyone got any ideas on why the treadmill should need to go to infinity then? (see halfway up page8). Surely it will only ever go as fast as the plane itself if that is what it is set to do? If the treadmill were trying to go fast enough to stop the plane then it would keep accelerating to no avail and hence would need to reach infinity.
|
|
|
Post by RWChris on Jul 23, 2009 19:01:11 GMT
Yeah you have to read the question very carefully otherwise it's easy to misinterpret.
There are two really big flying training organisations in the UK, one of which has a base in New Zealand where you do the majority of the training. I'm due back in the UK in November.
What's your friends boyfriend called? There's only about 150 of us out here so there's a good chance I'll know him.
|
|
|
Post by kidsgrove4 on Jul 24, 2009 2:44:38 GMT
Propeller or gas turbine? Personally, I feel the gas turbine JT9 engine from Pratt and Whitney was a superb engine, but I also think the RB211 from Rolls Royce was far more efficient. When General Electric brought out the CF6 for the 300 and 400 747's it was hailed as the finest engine as it was lighter, far more efficient and around 30% more powerful than the RB211. There wasn't a fucking treadmill in sight. ;D Discuss.
|
|
|
Post by french toast on Sept 16, 2009 21:55:46 GMT
but can it ;D
|
|
|
Post by scfcrmagic on Sept 16, 2009 22:05:44 GMT
but can it ;D if its a harrier jump jet it can ...fact
|
|
|
Post by edinburghstokie on Sept 17, 2009 6:58:53 GMT
Anyone else going to change their minds?
|
|
|
Post by Somebody_Told_Me on Sept 17, 2009 7:07:33 GMT
My answer is yes,
The planes engines make it move therefore it will go travel along the belt, the wheels will just turn faster, as fast as they would normally plus the speed of the belt in the opposite direction.
|
|
|
Post by edinburghstokie on Sept 17, 2009 9:05:36 GMT
good answer
|
|
|
Post by Somebody_Told_Me on Sept 17, 2009 12:24:24 GMT
Good answer or correct answer? LOL Don't answer that, I know I'm right. Makes you think, but christ some people are dim. ;D
|
|
|
Post by monkhousestokie on Sept 17, 2009 12:30:14 GMT
God, is this thread still running!
|
|
|
Post by edinburghstokie on Sept 17, 2009 12:51:30 GMT
God, is this thread still running! I think we are just building up to take off speed.
|
|
|
Post by edinburghstokie on Sept 17, 2009 14:38:06 GMT
, as fast as they would normally plus the speed of the belt in the opposite direction. Eh? That backwards force would create friction, slowing the speed of the wheels Aye, but if enough thrust is applied to the engines (not the wheels) they (the wheels) will turn faster than they would if the ground were stationary (for the equivalent thrust).
|
|
|
Post by edinburghstokie on Sept 17, 2009 14:55:01 GMT
indeed. As said before. it's a bloody long treadmill. Actually, the treadmill would have to be longer (tice the length of a usual runway) as it will need to fold back on itself...
|
|
|
Post by edinburghstokie on Sept 17, 2009 14:59:59 GMT
are you an aeronautical type then captain?
|
|
|
Post by Somebody_Told_Me on Sept 17, 2009 15:58:03 GMT
Allright, Let's assume an A380 with Rolls Royce engines are being used for the experiment. Weather clear, no factor whatsoever. A380 is at full payload. It's forward thrust from the engines will be about 80-84 thousand pounds. It will need about 14,000 feet of runway to take off at full payload, 1,200,000 pounds. Take off speed will be about 160-180 knots, as weather is not a factor. The treadmill will have to accelerate at the same speed as the aircraft, as well as being 16,000 feet long and capable of holding 1,200,000 lb and acceleration from 0 to 160-80 very quickly. The aircraft accelerates to V1 (Take off desicion speed, 160-180 knots) So does the treadmill. A380 gets up to rotating (safe take off speed) speed, treadmill holds same speed. If the A380 can theoretically maintain a slightly higher speed than the treadmill during rotating, it is almost impossible but the physics techincally allow it too happen, it can. I don't see why the treadmill would need to go any faster, if you run faster on a treadmill, you go forwards. The speed will stay at the speed its set at. The wheels will just have to go faster than normal take off to compensate for the speed coming the other way. Please explain.
|
|
|
Post by Somebody_Told_Me on Sept 17, 2009 17:09:42 GMT
I'm going on about wheels because you put. "Eh? That backwards force would create friction, slowing the speed of the wheels" by my wording, then wrote this! "The treadmill will have to accelerate at the same speed as the aircraft," Which is incorrect. If the treadmill is set to 20 knots and the take off speed (as you put it) is 180 knots then the wheels would spin at the 200 knots. the treadmill wouldn't go faster. So why would you put that??? As you correctly state the wheels have nothing to do with it taking off, but as I put in my first answer. The wheels would have to spin faster. So why put in about treadmill having to accelerate??? It wouldn't, would it.
|
|
|
Post by RWChris on Sept 23, 2009 4:58:17 GMT
Captain Quagmire, out of interest, what exactly do you do?
If you don't want to say on here then send me a PM.
Chris
|
|
|
Post by edinburghstokie on Sept 23, 2009 10:18:09 GMT
Captain Quagmire, out of interest, what exactly do you do? If you don't want to say on here then send me a PM. Chris His only 7 posts have been on this thread. Doubt he is a regular visitor to the GDB. PM him to see if you get a response.
|
|
|
Post by edinburghstokie on Jul 3, 2010 7:34:13 GMT
bump.
|
|
|
Post by Peters Pipe on Jul 3, 2010 15:31:35 GMT
Yes because the thrust is applied to the surrounding air, not through the wheels.
The wheels/tyres are unable to impart any force to the aircraft, barring the very minimal amount caused by friction in the (wheel) bearings. So the plane would move forwards, lift would be created and away it would go...
|
|
|
Post by StokieMatt on Jul 3, 2010 15:39:59 GMT
Yes because the thrust is applied to the surrounding air, not through the wheels. The wheels/tyres are unable to impart any force to the aircraft, barring the very minimal amount caused by friction in the (wheel) bearings. So the plane would move forwards, lift would be created and away it would go... what i said from the beginning, no one agree'd with me though. thank you ;d
|
|
|
Post by Peters Pipe on Jul 3, 2010 15:50:45 GMT
Really? Doesn't say much for the general level of intelligence around here then! ;D
I was surprised to see such a basic premise reach 9 pages to be honest!
|
|
|
Post by StokieMatt on Jul 3, 2010 15:58:25 GMT
^what he said
|
|
|
Post by Peters Pipe on Jul 3, 2010 16:01:27 GMT
Good thing there's no Karma anymore, I suspect I might have just taken "one hell of a beating..."! ;D
|
|
|
Post by StokieMatt on Jul 3, 2010 16:03:18 GMT
id of gave you some + for being an intellectual like myself ;D
|
|
|
Post by Peters Pipe on Jul 3, 2010 16:06:27 GMT
A little karma love-in.... My fave ;D
|
|
|
Post by StokieMatt on Jul 3, 2010 16:08:10 GMT
|
|
|
Post by Peters Pipe on Jul 3, 2010 16:10:48 GMT
;D
|
|