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# Airplane on a treadmill problem
Not only will it take off...



but I'm beginning to think that it's the only way to get the buggers into the air.
(tapeworm depressed beyond tablets, Sun 7 Jan 2007, 20:58, archived)
# Not only is that great
it's also SCIENCE!
(I helped save b3ta! Kamikaze Stoat £4.09, Sun 7 Jan 2007, 20:59, archived)
# BEST POST THIS YEAR
YOU WIN *clcik*
(I helped save b3ta! davew27 hevosen kuva!, Sun 7 Jan 2007, 20:59, archived)
# pfft.
Best one yet.
(Woody999, Sun 7 Jan 2007, 20:59, archived)
# PHALLIC RUNWAY ALERT
(I helped save b3ta! Yeknom. Incontinence and Premature ejaculation? Easy come, easy go., Sun 7 Jan 2007, 20:59, archived)
# Wrong Way?
Surely...

Neat anim though.
(I helped save b3ta! SixByNine By the power of Greyskull, Sun 7 Jan 2007, 21:00, archived)
# not if it was a treadmill.
(I helped save b3ta! mugatu, Sun 7 Jan 2007, 21:01, archived)
# Yes
You are correct

But it would not help if fly
(I helped save b3ta! SixByNine By the power of Greyskull, Sun 7 Jan 2007, 21:03, archived)
# It is a much debated subject.
www.boingboing.net/2006/12/11/airplanetreadmill_pr.html
(I helped save b3ta! Kamikaze Stoat £4.09, Sun 7 Jan 2007, 21:06, archived)
#
ooh, hold on, the thrust isn't from the wheels though, ignore the previous thought
(I helped save b3ta! Yeknom. Incontinence and Premature ejaculation? Easy come, easy go., Sun 7 Jan 2007, 21:08, archived)
# it would take off.
but the discussion thereof causes havoc.
(I helped save b3ta! Paster of Muppets is an incredible screen name, Sun 7 Jan 2007, 21:11, archived)
# Yeah. I feel a terrible guilt
for even bringing it up.
(tapeworm depressed beyond tablets, Sun 7 Jan 2007, 21:08, archived)
# Light the touchpaper
and run like fuck, that's what I say.
(I helped save b3ta! Kamikaze Stoat £4.09, Sun 7 Jan 2007, 21:10, archived)
# Just off out
as it happens.

Heheh.
(tapeworm depressed beyond tablets, Sun 7 Jan 2007, 21:11, archived)
# Shirly
it would /hinder/ flight. The engine would have to work harder to get the plane to go forwards (so the air would be moving more slowly over the wings).
(Carwash Maaaaaaaaarge!, Sun 7 Jan 2007, 21:09, archived)
# ^ this
(I helped save b3ta! urbane legend i have known the inexorable sadness of pencils, Mon 8 Jan 2007, 9:57, archived)
# ^this again
Although I'm sure this would be a great solution to help them land.
(I helped save b3ta! Father_Ted Drink!, Mon 8 Jan 2007, 10:47, archived)
# The planes engines
are pushing against the air to move the plane forward, it is not the wheels that provide the thrust. The wheels would just rotate faster than if the plane was travelling on a stationary runway. The plane would take off as normal.
(I helped save b3ta! Sammo, Mon 8 Jan 2007, 10:55, archived)
# so how would this help?
(I helped save b3ta! urbane legend i have known the inexorable sadness of pencils, Mon 8 Jan 2007, 13:34, archived)
# It doesnt help
It makes no diffrance
(I helped save b3ta! Letum Your Ad here £2.40, Mon 8 Jan 2007, 15:24, archived)
# There would be extra thrust needed
to counter the forces pulling against the wheels in the opposite direction.

If the treadmill was going the other way are you suggesting that would make no difference either?
(I helped save b3ta! .spanky is singing "PEANUTS!", Mon 8 Jan 2007, 16:00, archived)
# The treadmill
Will have no detectable difference to the take off.

The speed that the wheels are going round at is fairly irrelevant. Flight is based on airflow over the wings, not speed relative to the ground.

More effective would be a massive fan at the far end of the runway.
(fastandfurryous What was the question again?, Mon 8 Jan 2007, 16:37, archived)
# The speed relative to the ground does matter here,
because it's the same as the speed relative to the air.
The plane does move relative to the ground, and the air.

edit: aah, "the ground" meaning the surface of the treadmill, gotcha. That's irrelevant.
(I helped save b3ta! Newington, Mon 8 Jan 2007, 17:37, archived)
# but
if the plane was sat on the runway and they forgot to turn it off it'd end up wdged in a hanger.
(MrChimp previously Monsieur, Tue 9 Jan 2007, 1:43, archived)
# The speed relative to the ground
as in the actual ground, not the treadmill, is irrelevant too. The aircraft has to achieve a speed relative to the air to achieve flight.

Suppose the aircraft was a 747 with a rotate speed of 180kts. If there's a 30kts headwind, then it only needs to do 150kts relative to the runway for it to have 180kts of airflow over the wings, and thus fly.

This is why you always take off and land into wind.

It's also why an aircraft with a very low stall speed can fly backwards. A Tiger Moth has a stall of 35kts. If there's a 45kts wind down the runway it's entirely possible for it to have 40kts of airflow over the wings, but be moving backwards (relative to the ground) at 5kts.

/relative motion blog
(fastandfurryous What was the question again?, Tue 9 Jan 2007, 14:16, archived)
# The wheels wouldn't turn at all,
but the plane would move forwards and drag the treadmill round to match it. (So the treadmill in the animation is going the wrong way.)
(If the wheels and treadmill are both perfect, with no bearing friction and infinite friction between them.)
(I helped save b3ta! Newington, Mon 8 Jan 2007, 15:39, archived)
# It's not going the wrong way, it's illustrating a well known conundrum.
Have a read of www.straightdope.com/columns/060203.html for a concise explanation.
(I helped save b3ta! Paster of Muppets is an incredible screen name, Mon 8 Jan 2007, 16:35, archived)
# Yes, the conundrum is cool. I see that the plane definitely takes off.
I also thought that if the wheels and treadmill are 'perfect' (which they don't need to be) then the wheels don't spin, but the treadmill does, and it spins the other way than shown in this picture.

...which I now think is wrong, because there's no reason for only one of them to spin. They'd both spin, and both in the direction you'd expect, and the plane would still take off.
[I changed my mind again. The treadmill goes the wrong way.]


Thanks to tapeworm for introducing me to this!
(I helped save b3ta! Newington, Mon 8 Jan 2007, 17:20, archived)
# You don't know that they rotate in the wrong direction???
N00b!LOL, ROFLCOPTERS
(I helped save b3ta! davew27 hevosen kuva!, Sun 7 Jan 2007, 21:02, archived)
# Bloody good that is!
woo yay.
(I helped save b3ta! Mstandot I suppose I should post more often., Sun 7 Jan 2007, 21:00, archived)
# woo! that's ace
(I helped save b3ta! mugatu, Sun 7 Jan 2007, 21:01, archived)
# Woo sir!
(I helped save b3ta! Jahled Three shades of black, Sun 7 Jan 2007, 21:01, archived)
# hahaha
great work
(I helped save b3ta! but the hedgehog can never be buggered at all foreskin of the apocalypse, Sun 7 Jan 2007, 21:02, archived)
# Great !
WOO.
(|, Sun 7 Jan 2007, 21:11, archived)
# You're a new person, and you're posting good stuff.
And it's within 250k!

I think I love you!
(Nam_Rood, Mon 8 Jan 2007, 13:13, archived)
# but what effect does this have
on all the snakes?? And the inevitable terrorist situation that must ensue??

Nice pic btw - we need more thought experiments on the FP.

(I helped save b3ta! NLi10 lurker - 10yrs & counting..., Mon 8 Jan 2007, 16:57, archived)
# An idea
If the runway moved the other way, the pilot could gently move the plane onto it, at which point it will slowly start to accelerate forwards, depending on the friction of the wheels. Then the pilot could slowly apply the brakes, causing the plane to accelerate quickly down the runway and take off. The plane could accelerate more quickly in this way than with its engines alone, so you could use a shorter runway than normal. Of course, the pilot might then find that he can't start the engines, and the plane goes crashing to the ground.

If the runway also moved at the same velocity as the plane upon landing, you'd avoid any skidding, tyre damage and bouncy landings.
(StrongBad =! strong% AND StrongBad =! bad%: StrongBad = 1/0, Mon 8 Jan 2007, 19:55, archived)
# This is similar
to how aircraft are "launched" from an aircraft carrier deck.
(fastandfurryous What was the question again?, Tue 9 Jan 2007, 14:23, archived)
# yes
similar, but much more fun. One is just air-powered crap, and the other is a 160 knot treadmill.
(StrongBad =! strong% AND StrongBad =! bad%: StrongBad = 1/0, Tue 9 Jan 2007, 16:04, archived)
# Cor Blimey!
I didn't think people went back to post on these threads.

Thanks for clicking.

Hang on... am I allowed to reply to my own message?

Drat.
(tapeworm depressed beyond tablets, Tue 9 Jan 2007, 18:11, archived)
# it would
take off if the wheels were perfect
but they probably aren't and travelling at the increased speed would probably blow them causing the wheel to no longer act as a wheel and thus the plane would be resting on its belly on a moving treadmill
big explosion :P
but if perfect? it would just take off like normal :)
(Swany o¿o, Tue 9 Jan 2007, 20:16, archived)