plane on a conveyor belt?

[rpm]

An electric train is moving North at 50MPH.

The wind is blowing from the South at 50MPH.

Which way does the smoke go?

[Kurt]

Originally posted by Debonair
no pilot would taxi onto that contraption

Damn Straight!

[Kurt]

Ok, I'm a little surprised how many of our armchair aviators just don't get it...

Look, A propeller or a jet, they act on AIR, not on the ground.  You see, this is why they keep working when the plane loses contact with the ground... Get it?

Ok, so you have this conveyor and it will match GROUND SPEED....

That doesn't matter because ground speed doesn't fly airplanes... AIRSPEED fly's airplanes.

All you need to do is get the wings moving in the air and the required speed.  The speed of the ground (or a belt under the wheels) is absolutely irrelevent.

As soon as the propeller (or jet) can get enough forward velocity moving over the wing (forget the ground kids, it doesn't matter, we are pushing air, not belts) it will fly...

This is why a plane standing still can take flight if you blow enough air on it (which is why we tie them to hooks on the ground...) ..  If you take a Piper Cherokee and you weld the wheels to the axles so that it can not roll at all... Then you get a big freakin fan and you blow air over the wings at 120 mph, that byotch is going to leave the ground... Absolutely...

And if you do the same trick with a 747 and you increase the airflow to 200 mph, the same thing is going to happen...

Airplanes don't give a toss about ground... You see, this is why they fly.

CLUE IN.

Duh.

The most shocking part to me is that I have seen some of you pretend to be smart in other threads... now I know that your frame of reference was a salad bar.

To support my position... Make a good paper airplane and set it on your floor (it doesn't even have wheels)

Blow on that paper airplane with all your lung power (or if you are lazy, get a fan)... Guess what, it moved...  It lifted up and left where it was.

Done, g'nite... Mail me a check.

[Kurt]

Originally posted by rpm
An electric train is moving North at 50MPH.

The wind is blowing from the South at 50MPH.

Which way does the smoke go?

Smoke from the cigarettes I assume?

[JB88]

Originally posted by sluggish
Sure it will.  Thrust has nothing (or very little) to do with wheel RPM.

it isnt actual thrust being created so there is no additional airflow involved..  its like thinking that you will get blown off of a treadmill for running in place too fast.

[JB88]

however.  

were you to create a fan big enough and an anchor strong enough...

[Kurt]

Originally posted by JB88
however.  

were you to create a fan big enough and an anchor strong enough...

Doesn't matter, the wing will still exert lift against the anchor.  The fact that the wing may not be able to lift the anchor is irrelevent.. The plane makes enough lift to lift the plane.

You could tie an extra 747 to an otherwise flyable 747 and keep it from leaving the ground....

You see, JB88... Flight is not magic as you might believe.  Its physics... Just like the physics that say if you drop an 85 pound rock on your bare foot, its going to hurt... Even if you have a conveyor belt.

[JB88]

oh.

so, how does a wind tunnel work again?

you know, within the realm of physics and all.

tap tap tap...is this thing on?

[APDrone]

Originally posted by Kurt
...The plane makes enough lift to lift the plane.

...

So you're saying that every airplane generates enough air to lift itself off the ground.

If that is the case...


why do we need runways?


THIS would be a good one for mythbusters.

[Kurt]

Originally posted by APDrone
So you're saying that every airplane generates enough air to lift itself off the ground.

If that is the case...


why do we need runways?


THIS would be a good one for mythbusters.

With enough air over the wing, yes...  Air on the wing has no relationship to conveyor belt passing under the wing... Comprende?

Because in the absence of a convyer belt, the plane will move forward for a while before attaining adequate airspeed.  The key here is that the speed is not attained by moving the freakin wheels, its attained by moving the freakin AIR... why doesn't anyone get it?  IN your world, as soon as the airplane leaves the ground it loses its motive force and comes back down... Yet you know this is not the case - Because propellers and jets act against AIR, not concrete - and most especially not against conveyors.

Add a conveyor to prevent it moving forward and it will fly after covering that same amount of distance on the conveyor.

Come on Drone, you're smarter than this.  I know it.

Besides, everything the Mythbusters have looked at in the last 12 months is WAY below their level of knowledge... Its become a mainstream circle-jerk...

[Kurt]

Originally posted by JB88
oh.

so, how does a wind tunnel work again?

you know, within the realm of physics and all.

tap tap tap...is this thing on?

BINGO!

[APDrone]

Originally posted by Kurt
Because in the absence of a convyer belt, the plane will move forward for a while before attaining adequate airspeed.  The key here is that the speed is not attained by moving the freakin wheels, its attained by moving the freakin AIR... why doesn't anyone get it?  IN your world, as soon as the airplane leaves the ground it loses its motive force and comes back down... Yet you know this is not the case - Because propellers and jets act against AIR, not concrete - and most especially not against conveyors.

Add a conveyor to prevent it moving forward and it will fly after covering that same amount of distance on the conveyor.

Come on Drone, you're smarter than this.  I know it.

Besides, everything the Mythbusters have looked at in the last 12 months is WAY below their level of knowledge... Its become a mainstream circle-jerk...

Dude.. where did the initial question say you were driving the wheels with power?

To overcome the friction and start moving forward, wheels must roll. If they roll on a surface that effectively negates their forward motion, then the whole plane, itself, is not moving forward and is therefore not getting the airflow necessary to generate lift.

Like trying to cross a pond walking on a log that rotates toward you.  You aren't going anywhere.

[eagl]

You guys are funny.

The plane will fly.  The only difference will be that the wheels will roll very fast resulting in more rolling resistance, so the takeoff distance will be a bit longer (assuming the tires don't burst from spinning a lot faster than usual).

Think about it this way... what if instead of wheels, it had skids...  See?  Same thing.  You could put a plane with skids on a 500mph treadmill and if the engines have enough thrust to accelerate the plane against the drag of the skids on the treadmill, it'll still accelerate.

Other than people not having a grasp on how physics works or not being able to think it through, that's the only "trick" to this - there will be more drag than usual from the wheels (or skids, whatever) due to the higher wheel rotation speed.

[eagl]

Drone - your analogy is flawed.  Here's your real analogy - stand on a log in the water that rotates when you walk, but then strap a big fan on your back.  Sure the log will spin and spin and spin, but your speed will be determined not by how fast you run or the rotation rate of the log, rather by the balance between the thrust of the fan and the drag of the spinning log as it plows through the water.

You're forgetting that airplane wheels don't push the plane forward.  In fact, airplane wheels push straight down (weight) and actually "push" forward as they resist the rearward drag between the wheels and the ground.  The only force from the wheels that the engines must overcome on takeoff is that drag.  The wheels are simply not responsible for accelerating the plane forward so their only contribution to the whole thing is how much drag they're producing because the engines must push against that drag.

[Debonair]

also may be teh plane is aV-22:noid