Dr.ArmoMaxx

Yes or No?

Explain, if you can

alan0899

G'day Mate,
NO, no airspeed. no lift, no flight.

rwright142

alan0899 is spot on.

If the plane is not moving through air then no air will be passing under it's wings to give it lift.

A stationary plane will only fly if sufficient wind is forced past it to give it lift - like in a wind tunnel.

Ed Smith

It will be thrown off by centrifugal force. May even fly backwards for a while.

Ed S

RCVFR

My Feedback: (7)

Or, the friction from the treadmill might generate enough magnetic force, which, with the reinforcement of the corialis effect, could produce anti-matter which would propel the airplane at subsonic speed toward the most recent solar flare episode. That would constitute a take off.

Stickbuilder

I have seen overpowered models take off from inside a box, but that is not the question here. No, a treadmill will only generate wheelspeed. It won't generate airspeed, and that is what generates lift. Now if you had the treadmill out in a wind storm, that would be another issue entirely.

Bill, AMA 4720
WACO Brotherhood #1

Dsegal

> Or, the friction from the treadmill might generate enough magnetic force, which, with the reinforcement of the corialis effect, could produce anti-matter which would propel the airplane at subsonic speed toward the most recent solar flare episode. <

Boy, I am so glad that you explained that. Now I understand what is going on. (G)

da Rock

Airplanes have taken off of aircraft carriers that were heading DOWNWIND.

If having the runway move downwind can't keep the engine from pulling the airplane into flight, having a treadmill under the tires certainly isn't going to matter.

The tires roll freely for a reason. To remove any forces that would resist the aircraft's motion. They do that no matter what they're in contact with.

da Rock

The prop will pull that airplane forward against any resistance that it can overcome.

If the airplane didn't have wheels, the landing gear would grate against the runway and might stop the airplane from moving. But the design places wheels between the struts and the pavement. The wheels remove any resistance to motion.

The prop don't give a damn how fast the wheels are turning when they're rolling along a runway (that can't hold them back). So it won't mind if the wheels start off sitting on something that can't create ANY retarding force AT ALL. The prop is going to pull that airplane forward treadmill, pavement, or aircraft carrier.

Was it the F14 or the F16 that had a restriction on the throttle for takeoff. If the throttle was advanced too quickly, the airplane would simply tear the gear off while taking off.
And a number of powerful fighters have had restrictions on static runups. If the throttles were advanced, even with the brakes locked and the wheels chocked, the airplane would either drag off on the runway until airborne, or more probably wreck the gear and tip over.

so what kind of hold back force do you think a freewheeling treadmill is going to have? Since it's designed to give NO resistance. And airplanes have already proven they can take off against any resistance.

BillyGoat

Ok there are a few ways to read this question. If the plane is sitting on a treadmill, in essence moving the same speed as the treadmill, it will generate lift and “take off� if the treadmill reaches the take off speed of the plane.

A plane sitting stationary while a treadmill moves underneath can take off too. It will act just like it would any other time when the throttle is advanced. The treadmill will have to be runway length. It’s not like an auto that has to overcome the speed of the treadmill, to move forward. With a plane the prop is providing the forward motion and has no connection to the speed the wheels are turning.

saramos

If a plane is capable of taking off in about 5 feet, it's theroretically possible, but even so, unless it's a very small electric, and the treadmill is of an open design, the plane will crash into the upright posts of the cntrol panel and hand grips. Given all that, it would probably be easier if the treadmill was not actually on.

dbacque

My Feedback: (3)

The real answer is "What is your question?" Do you mean that the airplane gets no forward speed? Do you mean an infintely long treadmill but the plane is free to move forward? How fast is the treadmill? What is the rolling resistance of the wheels and axles on the aircraft? Do you mean the only airflow is the prop blast? Is the treadmill even turned on? How long is the treadmill? More data is needed on what you want to know.

This old horse has been sufficiently flogged several times on the aerodynamics forum. There's lots of reading matter on the subject there.

Tall Paul

The plane -will- take off.
http://www.youtube.com/watch?v=-EopVDgSPAk
This is an intelligence test.
Way too many people fail it.

Robotech

My Feedback: (9)

The original posters title implied that the airplane would be stationary. He asked whether it would take off, not if it could take off. Big difference.

saramos

After re-reading the question originally posted, I see I was not addressing the question in my previous post. I read it as 'can a plane take off from a treadmill?', which was not the question.

Also note, in the video link posted by Paul, only acceleration on a treadmill was demonstrated, the plane never achieved flight.

To test the question posted, one would have to turn the plane around, leave it un-powered, turn the treadmill on and see if it would achieve flight rather than simply fall off the end of the treadmill. can it be done?
I just successfully launched a paper airplane on my treadmill. The flight was very short, but it did gain a couple of inches of altitude.

Gary L.

This needs to go to myth busters ...

bkdavy

My Feedback: (1)

This debate when on for MONTHS in the aerodynamics forum. Go read that thread.

Brad

sharpshooter223

if it does i will not waste my time by watching it.

KitBuilder

Went on for months????
The original question: Will a plane "take off" from "sitting" (to be read stationary, no foward thrust) on a "running" treadmill.
no air over wings means no flight...
Hold a plane "inside" your car going down the road at 25 mph. Let it go... will it fly. I think not. The environment is moving 25mph, airspeed within the environment zero.

The planes wheels can spin at 1000 rpm for all we care... the plane will not fly as it is not moving through the environment or as well... the environment is not moving past it... (think seagull hovering).
Mike

KitBuilder

Went on for months????
The original question: Will a plane "take off" from "sitting" (to be read stationary, no foward thrust) on a "running" treadmill.
no air over wings means no flight...
Hold a plane "inside" your car going down the road at 25 mph. Let it go... will it fly. I think not. The environment is moving 25mph, airspeed within the environment zero.

The planes wheels can spin at 1000 rpm for all we care... the plane will not fly as it is not moving through the environment or as well... the environment is not moving past it... (think seagull hovering).

Question... answer if you can... when you close the refridgerator door... does the light go out???? lol (no pushing the lever to test!!)

Mike

bkdavy

My Feedback: (1)

This is my last attempt - The motive force for the plane is either the propeller or jet thrust. We'll just discuss propellor for simplicity.

The air medium the plane is working in is INDEPENDENT of the treadmill. The discussion in a moving car assumes the car is closed, and therefore the air medium is not moving relative to the plane, therefore the plane doesn't fly. Do the same thing in a convertible, and the plane will fly out of the car until it loses air speed.

The plane sitting on the treadmill pulls the plane through the air. The treadmill is NOT acting on the air the way the closed car is acting on the air. The plane must overcome the friction of the wheels on the axles. As long as the engine is capable of pulling the plane through the AIR, it will be able to generate air speed. There is no doubt some point at which the speed of the treadmill is so fast that the friction of the wheels will be high enough to prevent the engine from being able to overcome the force, and it will therefore NOT be able to generate any air speed. That point is dependent on the friction of the wheels on the axles.

Brad

saramos

Uh, I just tested a paper airplane on my treadmill. It is neither prop powered, or jet powered. I turned the treadmill on, set it for 8 mph, and set the paper airplane on the treadmill, It left the treadmill and flew ( a very very short distance ) and even gained altitude ( perhaps 2" ). Seems that with the proper plane ( such as a paper airplane ) sitting on a treadmill, a plane will take off. This is similar to how the Navy gets planes to take off from aircraft carriers. It's a catapult!

Jazzy

One of the things left out of the original post was whether or not the wheels were chocked to prevent the rotation of the wheels when the treadmill was turned on. If the wheels WERE chocked to prevent rotation and the impending acceleration of the airframe would not tip the aircraft, it would, as mentioned, act as a catapult. The forward momentum of the airframe would assist the prop. Ever hand launch before?
Otherwise, if the wheels or airframe were not chocked to prevent 'slippage' the runway would be moving but not the air relative to the airframe. The prop would do ALL of the work. Period. That is it.

This is just a question to get you guys suckered into a debate. Too many variables were left out.

I can't believe I even responded to such a silly thing...!

TimC

I took the original post to mean a treadmill running to match the forward thrust of the aircraft. It would seem to me, given a long enough treadmill, the plane would take off near normal. If you hold the plane a foot above the treadmill, it will go forward. I can't see it suddenly not being able to move forward just because the wheels are touching the treadmill. The wheels would be spun by the treadmill, but the thrust of the prop would simply add more rpm to the wheels as the plane proceeded forward. Friction in the wheels would make this forward progress slower than off a non-moving runway.
Airplane related, this reminds me very much of the discussion of the ballistics of a bullet fired by the nose gunner or tail gunner of a plane hypothetically traveling at the same speed as the muzzle velocity of the gun.
That would make for another entertaining thread.

TexasAirBoss

My Feedback: (22)

The theoretical and the practical are two different things. In the theoretical, the treadmill can attain any speed, even hundreds or thousands of miles per hour. Now friction is a factor, even for wheels and even for wheels mounted on ball bearings.
I took the original question, in the aero forum to be in the theoretical and that friction could be made to become a factor at some point.
OK, Youtubers, does a model airplane wheel have an infinite speed limit, or will friction limit how fast one can turn ?