preludespeeder

the question is answered simply by the fact that the conveyor does not control relative wind, it controls the wheel speed. no matter how fast that conveyor moves the engines will still move the plane through the air. if the wheels had any effect on the planes accerlation then the a plane could not accelerate once off the ground. also if the ground movement had an effect on a plane, then a landing plane would stop instantly once it touched down because the ground is stationary. remember what makes the plane move through the air, engines acting with the air not wheel friction. maybe an analogy is picture a hotwheel on a tread mill, if you hold the top of the car, the tread mill can go as fast as you want but the car will not move. If an outside force not relative to the ground acts on it, aka your hand pushing it foward, it will move forward regardless of the speed of the treadmill. the wheels will be moving faster but it will still move in the direction the force, your hand, is pushing it. just my one and half cents

TonyC

The question is not too vague, and it has only one answer.

Read the second sentence very carefully. I'll highlight the important words.




An airplane does not apply thrust through its wheels, so the conveyor is nothing more than a cute (and impossibly expensive) distraction. Airplane accelerates to 60 mph, the conveyor accelerates to 60 mph in the opposite direction. (The question as posed requires that the conveyor move at the same speed, but opposite direction, as the airplane. If the airplane is stationary, then the conveyor isn't moving either.) Wheels turn at 120 mph, and the airplane flies.



- Tony C

The truth only hurts if it should.

daytonaflyer

That is true. If the conveyor were moving at 60kts backward, the airplane would have to move at least 60kts in the forward direction to avoid getting pushed backwards. It would show 60kts IAS on the airspeed indicator. If it got fast enough, it would fly just fine.

ERAU1978grad

It's amazing how easy it is to confuse a pilot.



Ok everybody, let's think of it in terms you are familiar with.........imagine that you are making a connection between two gates at Atlanta Hartsfield. You are standing on one of those moving sidewalks. You feel a breeze in your face because you are moving right along as fast as the guy walking on the carpet next to you. Suddenly, you turn around and start walking in the direction from which you came, at the exact same speed as the moving sidewalk. The breeze in your face stops and you look over and see that the wall next to you is no longer moving. You are stationary.

Your Inertial Nav System is telling you that your are stationary.

Therefore you have zero groundspeed.

You also have Zero IAS.

No air over wing.

Plane no fly.

Plane stay on ground.

Trust me on this.

ryane946

I agree with the last post. No ground speed, no indicated airspeed, no air over the wings, no lift, no flight.

The only thing that will seem normal about the whole thing is the wheels will be moving at takeoff speed.

FlyerJosh

Gosh. Thanks for clearing that up for us Mr. ERAU grad. Too bad you're wrong... But don't try to figure it out- you might hurt yourself.

ERAU1978grad

I bet you have the big watch too. Do you plan on a career with McDonald's or Wendy's?

iflyjets4food

Part of the problem we have here is that an assumption is made that since the engine is interacting with air (causing thrust) that the wings are also interacting with the air. In this case, it would seem, both are not interacting with air. Only the engine is interacting with the air. The only thing that matters is relative wind. Does the airplane generate enough relative wind to fly without moving forward? If it does, please tell me why our own U.S. Navy launches fighters FORWARD off of the carrier, instead of creating a conveyor to launch from a stationary point. If we shut our engine down, and just let the belt run at our normal rotation speed, the airplane goes backward. It does so because it is connected to the belt at the wheels. Now, we fire up our engine and start adding power, we add enough power, and the aircraft accelerates enough, that we stop going backward. We are now stationary, and there is no relative wind over the wings. Without relative wind over the wings, we cannot ever hope to fly. The wheels are moving at rotation speed, however the airflow over the wings is nil. There has to be some airflow over the wings to create lift. Think of air as a stationary substance, which is a fair thought since the wind is zero. Somehow you have to make the air around the airplane reach rotation speed. Since the air is not moving, the airplane has to be moving through the stationary air at a speed equal to rotation.

All in all, this is just one of those rediculous college questions that could be avoided by majoring in business administration. It really doesn't matter one bit. I have yet to see a conveyor belt runway. If it were really possible, then in areas where the airport is getting closed in on all sides we could just have a conveyor belt. You'd have 747's getting in to Orange County (SNA).

HERE'S A GOOD THOUGHT: Maybe we could get the myth busters to try it. If anyone can make that happen, post it because I'd like to watch and see.

FlyerJosh

Hmmm, big words for somebody that has 8 posts and their very own space shuttle type rating. But, I'll play along cuz I have nothing better to do... (I'd also like to point out that ERAUDude slung the mud first... I just fired it back)

Yup I have a big watch. If you consider a $20 casio from Target a big watch. If you want, I can take a picture of it an post it here. I don't have anything to compensate for... big penis, small penis, it doesn't really matter- I'm still satisfied after my 30 seconds. Besides- I'm married As everybody knows, the sex stops when you say "I do". (Apparently you know who I am since you know my wifes name... but you're a bit late on the furlough joke, seeing that ACA hasn't been around since 2004.) Why don't you save us all some time and go back to flightinfo.com.

(Sorry HSLD- couldn't resist picking up the bait on that one.)

If you guys really want to rehash this subject, why not reread the thread that already has a zillion posts about it, or better yet read this article:

http://www.avweb.com/news/columns/191034-1.html

ERAU1978grad

Sweet response!