Will the plane fly?

[Hannibal]

LOL

It doesnt matter which way a conveyor belt moves under the planes wheels. The plane is not using the wheels to get it up to speed. The one thing to note is that the wheels will be moving at a higher velocity (airplane velocity + reverse conveyor speed= wheel velocity)

Riddle me this: How is it that a certain plane can take off while floating on the surface of water?? Is it using paddles or something? NO, it is using accelerated air that is passed over the surface of the wing, and is essentially "pulling" itself using the wind created by the propeller.

[SpoiledMan]

I'm with you Hannibal! The plane flies!

[Jeff Smith]

Alright, I am seeing a trend here. East of the Mississippi says no way and west says it flies. I think Meg's has a different recipe for west coast wax and the vapors are getting to you guys.

[Jeff Smith]

Originally posted by Shiny Lil Detlr
That is, unless it's one of those British (or Russian? Can't remember) planes that can hover or take off like a hellicopter due to a rotating engine

The British folks make the harrier which actually rotate nozzles which redirect the engine exhaust.

The US makes the JSF which follows the same concept as the British Harrier.

We also make the V-22 Osprey which is a totally different animal as compared to the Harrier. The V-44 is the next in line but is still being developed. When it flies, you better hope your house is well built.

[DFTowel]

Originally posted by Jeff Smith
I think a neater question would be would an aircraft stay alot with a tailwind greater than the foreward speed needed. Or would it hover?

I'll ask one of our test pilots here in a couple of minutes.

You are asking the question wrong... I think you mean will it hover if a HEADwind is equal to it's groundspeed and the answer is yes it will. In fct it can even fly backwards relative to the ground.

I've experienced this effect myself many years ago in an old Aeronca Coupe flying over the Delaware Water Gap. I had a headwind of over 60mph and an airspeed of 60 so in essence I "hoveredd" over the same spot for a moment. With a greater headwind or lesser sirspeed I would have been able to fly backwards.

See, an airplane doesn't care about groundspeed only airspeed. That is why the answer to the conveyer belt question is so obvious... no airspeed = no flight.

Now add this to the question, if the plane is polished with NXT will it... well never mind

[Jeff Smith]

Originally posted by Hannibal
LOL

NO, it is using accelerated air that is passed over the surface of the wing, and is essentially "pulling" itself using the wind created by the propeller.

.

Yes but the wind in and of itself as being forced through the engine or blades is not enough to lift the aircraft. The forward motion of the aircraft adds to this. I work at a Miltary flight test center. Some of our tests revolve around having an aircraft sit on the ramp and run it's engines at full speed for various legths of time. If what you are saying is true. Then we would have no control of these aircraft. Once they up at full throttle they could conceivably just take off into the air. Using your logic. We do not chain these aircraft down or secure them to the deck in anyway and run them full bore for hours on end. We call these High Power turns. If there were any risk whatsover of losing control of these aircraft we would have to chain them down in order to do this. Also, If this were the case. How does an F-16 fly then. Or any jet for that matter. Their exhaust does not expell over the wing.

[Jeff Smith]

BTW, Which LSP has been applied to this aircraft? I am sure that needs to be considered here.

[the other pc]

Originally posted by Don
Ground speed is not relevant. ...

Originally posted by Hannibal
...It doesnt matter which way a conveyor belt moves under the planes wheels. The plane is not using the wheels to get it up to speed. ...

This is the critical point.

As long as the landing gear roll freely, ground speed, or in this case conveyor speed, has absolutely no effect on the aircraft's forward motion or aerodynamic lift (assuming the wings are above the boundary layer, blah, blah, blah...). It doesn't matter what speed the conveyor is moving or whether it's going backward, forward or stopped. The conveyor will only affect tire rotational velocity, which has nothing to do with air speed.

No matter what the conveyor is doing the engine's thrust will accelerate the aircraft forward, the wings will generate lift and when the lift exceeds the weight of the aircraft it will fly.

Originally posted by Jeff Smith
...I work at a Miltary flight test center...

You don't need to take my word for it. Run this past one of your engineers.


PC.

[teterd]

The plane will fly!! No doubt about it!! The plane and prop do not care what the wheels are doing as long as they roll. The wheels provide no forward thrust. How fast they roll does not enter into the equation (except as friction). The wheels just go along for the ride. The convayor belt's sole purpose is to spin the non-driving wheels which will come to a stop when THE PLANE LIFTS OFF!!

[SVT Lightning]

Originally posted by teterd
The plane will fly!! No doubt about it!! The plane and prop do not care what the wheels are doing as long as they roll. The wheels provide no forward thrust. How fast they roll does not enter into the equation (except as friction). The wheels just go along for the ride. The convayor belt's sole purpose is to spin the non-driving wheels which will come to a stop when THE PLANE LIFTS OFF!!

The plane CAN"T lift off. It has no forward motion...."air speed".

No air-speed.....no lift...no take off! It just seems so logical to me and I have no engineering degree.

[SpoiledMan]

Originally posted by SVT Lightning
The plane CAN"T lift off. It has no forward motion...."air speed".

No air-speed.....no lift...no take off! It just seems so logical to me and I have no engineering degree.

Where is getting the idea that the plane isn't moving?

[the other pc]

Well, the original wording of the question is ambiguous. It says merely that it's "A plane" and doesn't specifically say whether it's an unpowered glider or if it has active propulsion. (Although I believe it implies propulsion because it does say "The plane moves in one direction".)

So the answer could be, insufficient information presented to derive a meaningful conclusion if you don't accept the implication.

If we assume it's a glider with no propulsion, then the result is that there is no motion at all, either of the airframe or the conveyor.

If we assume it does have propulsion, prop, jet, rocket, ducted fan, towline, catapult or whatever it will move forward and the wings will generate lift.


PC.

[Jeff Smith]

Originally posted by the other pc
Well, the original wording of the question is ambiguous. It says merely that it's "A plane" and doesn't specifically say whether it's an unpowered glider or if it has active propulsion. (Although I believe it implies propulsion because it does say "The plane moves in one direction".)

So the answer could be, insufficient information presented to derive a meaningful conclusion if you don't accept the implication.

If we assume it's a glider with no propulsion, then the result is that there is no motion at all, either of the airframe or the conveyor.

If we assume it does have propulsion, prop, jet, rocket, ducted fan, towline, catapult or whatever it will move forward and the wings will generate lift.

PC.

I did speak with one of our pilots about this this morning. He comments were (paraphrasing here): It would depend on the Thrust-Weight ratio of the aircraft. If the aircraft has enough then it can overcome the loss of lift due to not having the "initial' forward motion which adds to the lift. He said forward momentum was not being looked at carefully enough here.

He went on to say that the queston itself leaves alot to be desired as ther are two schools of thought here. Is the question refering to aircraft currently inproduction. or is it a theoretical question based on the "possibilty" that an aircraft can do this.

If it is asking about a currently produced aircraft, the answer would be no. Nobody is currently building an aircraft capable of this as the engines would be so strong and large that fuel efficiency would be compromised. Thus leaving you with a flying engine with a gas tank attached. Not pratical.

As for the possibilty is a plane being built specifically to do this. His thoughts were yes. But he did go on to say that he would never fly it. The stress loads on the aircraft so great that we really just don't have the manufacturing processes in place to build an aircraft to withstand them on a regular basis. At least not at this point in time.

So I guess the answer to the question is based on your perception of the question.

While telling me all this he was reading through the commentary so far. After giving me the above food for though he then added the comment that In His Honest Opinon. Gold class was the best.

Even though Ilike the Colonel's answer. I did have to help him change his windsheild wiper blades a few years ago.

[SVT Lightning]

Originally posted by SpoiledMan
Where is getting the idea that the plane isn't moving?

From the first post by Scottwax......

"A plane is standing on runway that can move (some sort of band conveyer). The plane moves in one direction, while the conveyer moves in the opposite direction. This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in opposite direction)."

I'm starting to get a headache from this one but it seems that the forward motion of the plane would be cancelled out by the oppposite and equal motion of the runway. As the plane speeds up, the runway speeds up. Think about walking on a treadmill. If you don't keep up with the speed of the belt, you'll get thrown off the back.

[SpoiledMan]

The speed of the road isn't important. Tie the plane in place in front of the nose on that same moving runway and it stays still. Add thrust to that and the plane moves forward on that same moving runway. The thrust is what makes the plane move NOT the wheels.