|
Post by nemesis on Feb 23, 2008 0:41:04 GMT 1
Jim, re re read it. You were right the frist time. It states in brackets that the runway is (some sort of band conveyer).
|
|
|
Post by eric on Feb 23, 2008 1:07:44 GMT 1
aerodynamics need forward motion, for a wing to be effective it must have airflow, if the plane is on a rolling road (not going forward ) there will be no lift to the wings. no matter how hard you push the engines if the plane cannot encounter wind resistance then the wings are useless. Forget lift and aerodynamics, that is only a by-product of an aircraft at takeoff velocity, the main point is; what is the propultion method? that is the engines.....they are not attached to the wheels as in a car, they push the aircraft forward by sheer brute force....the conveyor belt cannot stop the engines pushing the aircraft forward through the air....I have now polled three pilots and one engineer, they all agree that the engines would be able to push the aircraft forward through the air regardless of the belt attempting to match the speed of the aircraft. I am a very sad person....yes?
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Feb 23, 2008 1:19:53 GMT 1
Actually the engines don't push the plane forward. The planes moves forward as a result of the reaction to the air getting pushed back by the propellors or jet engines. For every action, there is an equal and opposite reaction. - Newton's Third Law of Motion www.glenbrook.k12.il.us/gbssci/phys/Class/newtlaws/u2l4a.html
|
|
|
Post by Baz on Feb 23, 2008 2:28:59 GMT 1
Yeah what have I started!!! Just feel happy that this is raging on across the internet on many forums lol. Oh and I do belive to solve this we need to appropriate a plane and a large factory conveyer belt and make a day of wizzing planes along a conveyer belt rofl Afk Shooting is too good for you ;D I'm amazed you still have any Karma left rofl baz
|
|
|
Post by eric on Feb 23, 2008 11:44:03 GMT 1
Actually the engines don't push the plane forward. The planes moves forward as a result of the reaction to the air getting pushed back by the propellors or jet engines. For every action, there is an equal and opposite reaction. - Newton's Third Law of Motion www.glenbrook.k12.il.us/gbssci/phys/Class/newtlaws/u2l4a.htmlWell done skyfire, you've just made the point, the aircraft has no choice but to move forward as a result of the thrust from the engines. The action; thrust from the engines on the airframe......the result, air gets pushed out one way (backwards), and the aircraft gets pushed the other way (forwards). That is the action and reaction....what the wheels are doing is not part of the equation! Nice one!!!!
|
|
|
Post by Mike B on Feb 23, 2008 11:46:06 GMT 1
Let's look at it another way, forgetting about wheel speed, friction etc. 1. If the engine is switched off and the conveyor belt goes in reverse, the plane will move backwards from point X. 2. If the conveyor belt is switched off and the engines thrust the plane, the plane will move forward from point X. 3. If the conveyor belt goes in reverse and the plane thrusts forward at the same speed, the two motions will result in the plane staying stationary above point X and the air molecule above the plane will keep it's position relative to the wings and therefore no lift will be provided and THE PLANE WILL NOT FLY. ;D ;D ;D Now, if you are still sceptical, try the following experiment. Get a long piece of paper (fanfold paper or newspaper). Get a model car and push it along a table top - it goes forward. Now put the paper on the table top, grab the back edge of the paper, note the car's position, push the car forward on the paper and pull the paper backwards. When the car runs off the front of the paper you will see it's position on the table is where it started from!
|
|
|
Post by nemesis on Feb 23, 2008 12:17:23 GMT 1
Eric, you say
The action; thrust from the engines on the airframe......the result, air gets pushed out one way (backwards), and the aircraft gets pushed the other way (forwards).
That part is absolutely correct but you are consistently ignoring the fact that in this scenario, the conveyor belt is running in the oposite direction to match that speed.
You keep referencing pilots, mechanic etc. I served in the Army Air Corps. I lived and breathed aircraft and aviation every day for six years so I'm not making this up. It's basic theory of flight. If an aeroplane has no airflow over the wings, it will not fly. Otherwise we could all get in our Mini Coopers, turn on the engine and fly to Asda instead of dealing with all that traffic. ;D
|
|
|
Post by eric on Feb 23, 2008 13:17:17 GMT 1
Ok, I give up!
We shall just have to disagree on this one, but could I please have on of these flying car thingies, 'cos it's impossable to get from one end of my town to the other!!!
|
|
|
Post by nemesis on Feb 23, 2008 15:04:28 GMT 1
Lol, believe me, if I could have one of those flying car thingies, myself I would. Getting through my town at rush hour is a nightmare and getting worse by the day.
It reminds me of those old 1950's documentaries where they were saying in a few years we would all be flying around in small helicopters rather than family cars.
|
|
|
Post by jim on Feb 23, 2008 17:53:27 GMT 1
aerodynamics need forward motion, for a wing to be effective it must have airflow, if the plane is on a rolling road (not going forward ) there will be no lift to the wings. no matter how hard you push the engines if the plane cannot encounter wind resistance then the wings are useless. Forget lift and aerodynamics, that is only a by-product of an aircraft at takeoff velocity, the main point is; what is the propultion method? that is the engines.....they are not attached to the wheels as in a car, they push the aircraft forward by sheer brute force....the conveyor belt cannot stop the engines pushing the aircraft forward through the air....I have now polled three pilots and one engineer, they all agree that the engines would be able to push the aircraft forward through the air regardless of the belt attempting to match the speed of the aircraft. I am a very sad person....yes? I must disagree prior to takeoff all aircraft rev engines to maximise thrust. the brakes hold the aircraft stationary until released, ergo if the plane aint moving through the air it cannot take off regardless of what the engines are doing. wings need forward motion to create lift.
|
|
|
Post by nm on Feb 23, 2008 18:59:29 GMT 1
A stationary plane can have quite an airflow over the wings: propellers do that, especially multi-engine aircraft with wing-mounted engines.
NM
|
|
|
Post by nemesis on Feb 24, 2008 1:18:54 GMT 1
That's true, nm but that air is very disrupted and usually in the form of vortices (sp). Useless for lift in itself.
|
|
|
Post by eric on Feb 24, 2008 1:26:16 GMT 1
If the aircraft is stationary, there is no way it can take off...unless it is blowing a force 9 gale straight at it!
It must be moving forward to take off, the only questions is one of whether or not the aircraft WOULD be able to move forward.
One day someone will do a proper test, and I look forward to that!
One of the pilots I spoke to is off in a week or two to brush up on his flying at a simulator (one of the proper ones), and he said he would see if they can program the senario into the computer.
Whats the bets it would go into meltdown!!!
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Feb 24, 2008 2:16:33 GMT 1
If the aircraft is stationary, there is no way it can take off...unless it is blowing a force 9 gale straight at it! It must be moving forward to take off, the only questions is one of whether or not the aircraft WOULD be able to move forward. One day someone will do a proper test, and I look forward to that! One of the pilots I spoke to is off in a week or two to brush up on his flying at a simulator (one of the proper ones), and he said he would see if they can program the senario into the computer. Whats the bets it would go into meltdown!!! Unless of course it's a Harrier Jump Jet. They don't need a runway to take off. I've seen on tv, (several years go now) of 1 of them flying backwards at the head of a formation of helicopters. The sim might crash, but doubt it would meltdown, or at least I hope it don't. - lol
|
|
|
Post by jim on Mar 1, 2008 11:04:36 GMT 1
yeah but the harrier is not using its wings to takeoff it is literally rising on vectored jet thrust similar to a rocket
|
|