FINALLY! Mythbuster, Dec 12th, MUST WATCH!

[legendboy]

i was a bit mis understood on what exactly they were doing

[b_t]

Originally posted by kertejud


A Camel could defintely take off from a carrier. The British used Swordfish biplanes on their carriers in WWII which were much heavier and didn't have a much higher speed or rate of acceleration compared to the Camel. And of course the Camel being an Allied aircraft, it wouldn't really matter whether or not Germany had any aircraft carriers.

However all of this is moot considering the Camel wasn't "shot" of any type of vessel nevermind a yet to appear flattop aircraft carrier.

[/nitpick]

Whoops, I mistook the Sopwith Camel for the plane the Red Baron flew and didn't even know the Swordfish existed. I don't think an aircraft quite like the Camel was a good choice for anything but a fixed deck though, and I certainly would not want to land one on a carrier.

[[GaGe]]

here's my theory:

if the conveyor belt is always travelling at the exact opposite speed as the plane (same acceleration in different directions), the plane will NOT take off. doesn't matter if the plane is powered by the jets and not the wheels. the thrust from the jets give the force to propel the plane forward, and the conveyor belt uses frictional force to push the plane backwards.

if the plane is travelling at x km/h, that means the base of its wheels is travelling at x km/h in the opposite direction. if the conveyor belt is travelling at the exact opposite speed of the plane, that means that the conveyor belt is ALWAYS travelling at the exact same speed as the base of the wheels (the wheels are not spinning faster because of the conveyor belt). since the relative speed between the tires and the conveyor belt is 0, this experiment would be the same as trying to take off a plane with locked wheels on a rubber runway, which is not possible.

[962 kid]

Originally posted by [GaGe]
if the conveyor belt is travelling at the exact opposite speed of the plane, that means that the conveyor belt is ALWAYS travelling at the exact same speed as the base of the wheels (the wheels are not spinning faster because of the conveyor belt). since the relative speed between the tires and the conveyor belt is 0, this experiment would be the same as trying to take off a plane with locked wheels on a rubber runway, which is not possible.

Close, but it would not be the same as trying to take off with locked wheels, but rather trying to take off with no wheels, but on a frictionless surface (put simply). All of the forces between the wheel and the belt are basically negated, which makes it impossible for it to oppose the force of the thrust from the jet engines.

[[GaGe]]

Originally posted by 962 kid


Close, but it would not be the same as trying to take off with locked wheels, but rather trying to take off with no wheels, but on a frictionless surface (put simply). All of the forces between the wheel and the belt are basically negated, which makes it impossible for it to oppose the force of the thrust from the jet engines.

if you stood at the end of a conveyor belt and held a shopping cart in the same position on the belt, you're applying the same force as the belt just holding it there. the conveyor belt isn't a frictionless surface. if you applied the same force to the cart on ice (frictionless surface), then it would move forward.

[962 kid]

The shopping cart will stay motionless on the conveyor belt whether or not you are holding it. No matter how fast the conveyor belt is spinning, the wheels will spin just as fast in the opposite direction keeping it motionless. If I were to push the cart however, it would move in the direction I pushed it.

[suen17]

No matter how fast the conveyor belt is moving, the plane will take off.

As mentioned before, it is simply a case of Newton's second law. At any given time before takeoff, the thrust force will be ALWAYS be greater than any force in the opposite direction. For a plane to stay "stationary" on the belt, it would require a force in the opposite direction of equal magnitude. On a belt, there is no way in hell that the force of friction, the only force acting on the plane from the belt, is equal to the thrust force. Thus, the plane will move forwards, creating the aforementioned airflow, and take off.

The friction force between a jet's tires and the runway, or belt, is so minute that it could even be considered negligible when compared to the thrust force.

The difference between the plane and a car on conveyor belts is that the plane's thrust force is acting on an air mass, and a car's "thrust" or driving force is acting directly on the belt through the tires.

[[GaGe]]

Originally posted by 962 kid
If I were to push the cart however, it would move in the direction I pushed it.

that only occurs if the conveyor belt remains at a constant speed. the cart's wheels end up moving faster than the conveyor belt, which is why it moves forward.

if the wheels and the conveyor belt were both accelerating at the same rate, the cart would remain in the same spot

if the conveyor belt is always travelling at the exact opposite speed as the plane (same acceleration in different directions), the plane will NOT take off

[Go4Long]

I can't believe there's still people arguing that this plane is going to take off.

newton's second law applies to the thrust generated, yes. however the thrust of an airplane is not what causes it to take off. the thrust is used simply to move the air craft forwards, the lift needed to make the aircraft take off is actually generated by the air flow over the wings caused by the velocity at which the plane is moving forwards.
think about it like this, if an airplanes ability to take off was determined solely by it's thrust, then there would be no reason for there to be a catapult on aircraft carriers. there would just be a bolt to hold the aircraft down until it's engines made enough thrust, then release the bolt and VOILA you're airborn. but no, instead, they want the engines at full thrust, and the airplane to be moving with enough speed for the wings to generate lift.
a plane can't fly without moving forwards, period. a gliders thrust factor is 0, but yet if you get it moving, it flys, that's because lift is generated by the wings, not the engines.

[962 kid]

Originally posted by [GaGe]


that only occurs if the conveyor belt remains at a constant speed. the cart's wheels end up moving faster than the conveyor belt, which is why it moves forward.

if the wheels and the conveyor belt were both accelerating at the same rate, the cart would remain in the same spot

The cart will remain motionless barring any outside force, no matter what the speed of the conveyor belt is. The sooner you understand this, the sooner you will be able to understand the problem

[n1zm0]

Originally posted by b_t


dude, are you fucking serious? Not only are you the worst physician in the world, but also the worst historian. Problem A - there were no aircraft carriers in World War I. Problem B - a Sopwith Camel could not take off from a deck as short as those on even a modern aircraft carrier. Problem C - Germany has never had any aircraft carriers ever, so uh...

ha, where the hell did you learn this from,
A- HMS Ark Royal ,HMS Furious, read up
B-The did not take off from a runway deck, they were launched
C-Wherever you got the idea that a Sopwith Camel is German must be your own history books, they are british.. never said Germans had an aircraft carrier

I still stand by the fact that an a/c needs airflow to perform lift.

[962 kid]

^^ noone is disputing that fact. Learn simple physics.

[Lagerstatten.ca]

Just got a reply back from the President of the PASA (Physics & Astronomy Student's Association) Club at the University of Calgary:

"Yes, the plane will still take off. The conveyer belt will not slow down
the body of the plane at all, it will only speed up the wheels of the
airplane to twice its angular velocity. Contrary to popular belief, the
plane will still be moving forward at it's takeoff velocity. Despite the
velocity the conveyer belt is moving at (it could even be moving faster or
slower than the plane) the plane will still have a forward velocity."

John Nguyen
PASA, President

Hope this resolves the debate.

-TT

[b_t]

Originally posted by Lagerstatten.ca

Hope this resolves the debate.

-TT

The debate was resolved on the first page but is still continuing, so it probably won't.

[Rockski]

ill bet a bucket with a gold handle says it doesnt take off

[alloroc]

B-T
Wow so many things wrong.
First you incorrectly started starting talking about aircraft and aircraft history in thread I was reading.

Originally posted by b_t
Not only are you the worst physician in the world,

I think you mean Physicist, physicians are medicially trained..

Originally posted by b_t

but also the worst historian. Problem A - there were no aircraft carriers in World War I. Problem C - Germany has never had any aircraft carriers ever, so uh...

Oh geez! USS Langley, HMS Castor to name two.

Germans did launch planes off boats in both WW1 and WW2. German Arado Ar196's routinely were used for NAVAL aerial recon - they flew off german ships. (you have heard of the Bismark haven't you?) The planes flew2 off a 32m long deck equipped with a catapult.

Originally posted by b_t

Problem B - a Sopwith Camel could not take off from a deck as short as those on even a modern aircraft carrier.

They can and they did.
Check out the takeoff length (near end of video - how far? certainly less than the field length of a modern CV.
http://www.youtube.com/watch?v=wH3ap...elated&search=

Originally posted by b_t

Anyway, the fuselage is independent of the wheels, like you just said, which are connected directly to the fuselage... and the wings are directly connected to the fuselage... so how do the wheels affect the wings at all?

Do you not see the wheels as being attached to the plane? do the wings fly off independently? Or in your view does the landing gear - wheels included fall off at takeoff.
If the wheels are rotating at takeoff speed on the conveyor - and the conveyor os moving at takeoff speed in the opposite direction - the plane will not be at full power (planes do have throttles) and it will be stationary relative to ground.

There are Two pysically possible scenarios as the question is written

One plane stationary relative to ground.
One plane moving relative to ground.

[rage2]

Originally posted by alloroc
Do you not see the wheels as being attached to the plane? do the wings fly off independently? Or in your view does the landing gear - wheels included fall off at takeoff.

But explain how the conveyor belt can exert enough force to negate the force of the jet engines. Remember that the wheels rotate freely, which effectively "disconnects" the wheels from the rest of the plane.

Originally posted by alloroc
If the wheels are rotating at takeoff speed on the conveyor - and the conveyor os moving at takeoff speed in the opposite direction - the plane will not be at full power (planes do have throttles) and it will be stationary relative to ground.

You are correct here, the plane will not be at full power. It'll be at 99.99999999% power. Because of the ultra low coefficient of friction of the bearings, the energy from the conveyor will have enough to make a 0.000000001% difference.

[BerserkerCatSplat]

Originally posted by Rockski
ill bet a bucket with a gold handle says it doesnt take off

You're on, sucker!

[benyl]

Originally posted by n1zm0
^ the a/c is not moving it says it will be traveling at take-off speed, on a conveyor belt, thus being 'stationary',

omgwtfbbq!

If the plane is traveling at take off speed, HOW THE HELL is it stationary?

[rip]

Lock this untill the episode airs. This has been debated twice and people still can't get their head around the fact that the plane does have forward velocity.