Will a plane on a conveyor belt take off?

[3vXT]

I got this from another forum and am curious about what people on here think.

If a plane is traveling at takeoff speed on a conveyor belt, and the belt is matching that speed in the opposite direction, can the plane take off?

[LTDHO]

This was posted last year or something.

As the wheels do not move the plane but the thrust does.
So the plane will fly with the wheels spinning at twice plane speed.


close thread

[scoupedy]

Its basic vectors: NO as the plane has zero Airspeed

[Outbackjack]

An aircraft needs airflow over its wing to generate lift. If the A/C is staionary it is not generating lift, therefore it cant take off.

[Blonk]

NOoooooooooooooooooooo..........

Not this one again...

The AC generates thrust from the environment and not the earth.....IE the jet will use propulsion from the air not the ground.. The damn thing would take off even if it was on skids...... The damn thing would take off even if its laying on it belly

[TheSneakiness]

http://www.fordforums.com.au/showthread.php?t=28901

[Dave_au]

For the love of god, not again.

As mentioned, a plane develops momentum from the thrust of it's engines pulling and pushing air, the wheels are not powered in any way. What would actually happen in this hypothetical, the plane would actually pull itself up the conveyor belt as if it was a normal length runway, with the wheels spinning twice as fast as they needed to (ignoring friction, wheel resistance etc). Once the correct airspeed is reached the wings will generate lift and the plane will take off.

The best example is to think of an aircraft fitted with skis and taking off from a snow field. Without the props pushing the plane forward there is no movement at all.

[3vXT]

OK, so its been on here before.
Judging by the first 2 responses it wasn't resolved. I've got my own opinion, the reason i posted it was to put a pole up to see more clearly what everyone else thinks.

[aye you]

no, the speed f the aircraft relative to the wheels in contact with the ground/earth is not what causes flight, it is the speed of the airflow over the wing and the angle of the wing to the airflow. An aircraft can be completly stationary but, as was seen in Cyclone tracy, if the wind moving over the wing generates enought lift to counter act the weight of the aircraft then it will lift off. This is why we tie down our planes when their not in use because in Cyclone tracy aircraft where becomming airbourne from the speeds of the wind alone. Also why we takeoff into and land into the wind, means that engine has to do less work to maintain forward speed and lift

Eg

(aircraft travelling 80kts) -----><------ (Wind at 20kts) total airspeed = 100kts

[Charliewool]

NOOOOOOOOOOOO!!.. CASPER Don't look!!!! : : :

[ardei]

I always believed that it would be stationary but this video convinced me otherwise:

http://www.youtube.com/watch?v=-EopVDgSPAk (skip through all the boring bits to the actual experiment)

[Charliewool]

Originally Posted by ken2903

OK, so its been on here before.
Judging by the first 2 responses it wasn't resolved. I've got my own opinion, the reason i posted it was to put a pole up to see more clearly what everyone else thinks.

First TWO responses??? Try FOUR HUNDRED & THIRTY TWO responses!!

[3vXT]

Originally Posted by charliewool

First TWO responses??? Try FOUR HUNDRED & THIRTY TWO responses!!

I just had a quick look at the old thread. 18 pages and the last post almost 2 years ago. There are lots of new members on here since then (myself included).

As LTDHO said, i believe the plane would take off, with the wheels spinning freely at twice the speed of the conveyor belt.

EDIT: Mods please dont block the thread, a little passive disagreement never hurt anyone.

[aye you]

oh, just to add to my previous post, a jet aircraft will not take off as the engines provide no lift, only thrust, and a propeller aircraft will not take off as the engine/s thrust passing over the wings will not provide enough lift to become airbourne, if they did, wings would be a heck of a lot smaller

[the_scotsman]

Oh ffs..I'm guessing the OP is a member of Overclockers.com.au forum. They have re-opened the issue as Mythbusters are going to have another go at this.

The plane will take off...the question clearly states the plane is travelling "at takeoff speed"....why on earth wouldnt it take off if it is flying at takeoff speed?
The only difference between this and any ordinary takeoff is that a conveyor is running the opposite way against the aircraft at the same speed as the aircraft groundspeed. As has been poimted out several times, it just means the wheels will spin at twice the speed of the aircraft...nothing more to it...

[Peuty]

No it won't. Simple.

Close Thread.

[SB076]

Originally Posted by aye you

oh, just to add to my previous post, a jet aircraft will not take off as the engines provide no lift, only thrust, and a propeller aircraft will not take off as the engine/s thrust passing over the wings will not provide enough lift to become airbourne, if they did, wings would be a heck of a lot smaller

The plane will take off as you said the engines provide thrust therefore the plane will move on the conveyor which will enable sufficent airflow over the wings which allows the plane to take off (the conveyor can spin around as fast as it wants it wont keep the plane stationery)

What a great thread first we hear the FPV want to bring back the GT-HO and now this thread resurfaces - this should be fun

[Charliewool]

I think the definitive answer was submitted by our member.. 42.57lb back in Dec.05
[Quote] if I glued a chicken to a skateboard and then put fire crackers up the chicken's erse, the I put the skatboard (with chiken attached) a tredmill, then I lit the fireworks BUT I also had a hypotheical device that instantaneoulty matched the power generated by the fireworks, but in the opposite direction, the chicken would expode on the treadmill and you would have a very messy gym.

then you would probably tell the person who own the gym that the feathers and blood everywhere had nothing to do with the chicken and the skateboard (or the fireworks) because the wheels of the skateboard are not important to the systems energy transfer.


Game over man game over, I can't convince you, you can't convince me. I'm not going to perpetuate, it. I think my education is lacing where yours is not (not being a pr1ck) so we'll just have to leave it there.

Then the RSPCA will arrest me and I'll be in jail. kool. [end Quote]

[3vXT]

Originally Posted by the_scotsman

Oh ffs..I'm guessing the OP is a member of Overclockers.com.au forum. They have re-opened the issue as Mythbusters are going to have another go at this.

The plane will take off...case closed...and thread closed soon too methinks...

No, i got it from another forum where people aren't afraid of everyone else's point of view. Half the people in the old thread aren't even posting on FF these days anyway, what is the big problem? I put a pole on to see what the general opinion is without having to read 18 pages of 2 year old posts.

[the_scotsman]

I think people are seeing 2 different questions...the treadmill or conveyor is matching the speed (groundspeed) of the aircraft, not the thrust of the aircraft...the conveyor could be spinning 5000 km/h it would make no (or very little) difference...the plane will roll along the conveyor as normal and take off.

[aye you]

yes, in that case it will, because the aircraft is not stationary the air is not flowing over the wing. im reading the question as the converyor belt is matching the aircraft, thus keeping it stationary, eg it has no forward momentum. I mean i run on a treadmill, maintaining my position relative to the surrounds, shoot me with a speed gun, it'll register 0 (give or take for varience) No momentum = no velocity= no airflow = no lift = no flight. Introduce a moving airflow we have a different. Eg place a the whole experiment into a wind tunnel and make sure there is, lets say 60kts *take off speed for a C172) then it will take off, no matter what speed the converyor belt moves, because its the airflow over the wing that wil initiate flight. No lift, No flight, Lift can only be generated by airflow gained from forward momentum

[the_scotsman]

yes, your legs (the part in contact with the ground) are what power you forward.

In the case of a plane, wheels (the paart in contact with the ground ) do not drive the plane forward, the engines do...which are NO WAY related to contact with the ground.

How could a conveyor match the "aircraft" as you put it? simply not possible as far as I can see...the wheels freewheel and so you could never oppose the aircraft itself.

[SB076]

Originally Posted by aye you

yes, in that case it will, because the aircraft is not stationary the air is not flowing over the wing. im reading the question as the converyor belt is matching the aircraft, thus keeping it stationary, eg it has no forward momentum. I mean i run on a treadmill, maintaining my position relative to the surrounds, shoot me with a speed gun, it'll register 0 (give or take for varience) No momentum = no velocity= no airflow = no lift = no flight. Introduce a moving airflow we have a different. Eg place a the whole experiment into a wind tunnel and make sure there is, lets say 60kts *take off speed for a C172) then it will take off, no matter what speed the converyor belt moves, because its the airflow over the wing that wil initiate flight. No lift, No flight, Lift can only be generated by airflow gained from forward momentum

When you run on the treadmill your feet are trying to propel you forward hence the conveyor can maintain your position - But with a plane the jets engines are moving it forward (not the wheels) therefore the plane will drag itself through the air and move it forward which will create air flow and the plane will take off

Edit what Scotsman said

[XR6WGN]

Is it a small plane or a dirty big conveyor belt?????

[Outbackjack]

Originally Posted by Outbackjack

An aircraft needs airflow over its wing to generate lift. If the A/C is staionary it is not generating lift, therefore it cant take off.

Wrong wrong. the palne can take off. .....

[the_scotsman]

Originally Posted by Outbackjack

Wrong wrong. the palne can take off. .....

Yea, you tell.......you :

[EA2BA]

Been done before, have fun reading

http://www.fordforums.com.au/showthread.php?t=28901

[The Monty]

Aararrrrrghhghhghghghghg
Why did you go and do that?
Your evil, that is not OK.
This brings back BADDDDd memories....

[Outbackjack]

Originally Posted by the_scotsman

Yea, you tell.......you!

Yeah , what a fool......

[the_scotsman]

EDIT: Never Mind...