Mythbusters tackles the plane/treadmill

[darkred87T]

Since the wheels are not propelled, the conveyor will have absolutley NO effect on the planes body.

Bingo!

 

[notacarlo]

Now we gotta throw bingo into this!?:biggrin:

I understand the "conveyor" really is immaterial. The plane will still need to be held in place. If it matched the forward speed of the plane the entire time it will go nowhere. Like said above. Not sure about bending space and time.....but I will believe anything at this point.

be right back....running low on whipped cream cans.

 

[SouthernCal GN]

Chanute Air Museum


Of course, MY logic could be all FUBARed!!


VTOL- Vertical take off is great for getting off the ground; if you don't transition to forward flight (using the wings to generate lift vice pure engine thrust) you will soon meet earth once again as you run out of fuel......

In the same vein- helicopters. If you tilt the rotors without spinning the blades, you go nowhere. If the tail rotor goes away, the 'copter autorotates, and control is lost.

Both rotor assemblies are wings that rely on air moving over the foil to generate lift.

 

[Madcat455]

Now we gotta throw bingo into this!?:biggrin:

I understand the "conveyor" really is immaterial. The plane will still need to be held in place. If it matched the forward speed of the plane the entire time it will go nowhere. Like said above. Not sure about bending space and time.....but I will believe anything at this point.

be right back....running low on whipped cream cans.

It can only speed up the conveyor in the oppisite dircetion of the aircrafts movement and match speed.

The only effect that'll have is making the planes wheels rotate 2X the speed of normal take off... but the planes body will act as if the conveyor isn't even there.


Plane engines move relative to the air around them... not the ground underneath them. NOW.. if you have a HUGE fan matching the planes air speed in the same direction of the planes movement.. then it wouldn't fly.:biggrin:

 

[Pitbozz]

Think about a treadmill at your gym, and if you don't go to a gym, quit reading this thread and get off your lazy ass!!:biggrin: If you got on the treadmill with rollerblades/skates and tied a rope to the handle and around your waist, the treadmill would hold you stationary. Right? Now have someone push you from behind or you pull on the rope. What happens? You move forward. That is what the thrust of the engines on a plane will do.

 

[SouthernCal GN]

Think about a treadmill at your gym, and if you don't go to a gym, quit reading this thread and get off your lazy ass!!:biggrin: If you got on the treadmill with rollerblades/skates and tied a rope to the handle and around your waist, the treadmill would hold you stationary. Right? Now have someone push you from behind or you pull on the rope. What happens? You move forward. That is what the thrust of the engines on a plane will do.

Ah, but look at this:
"Imagine a plane is sitting on a massive conveyor belt, as wide and as long as a runway. The conveyer belt is designed to exactly match the speed of the plane, moving in the opposite direction."

According to the above, your forward motion would be instantly negated by the opposite direction of the treadmill.

 

[Brer Rabbit]

Easy there Dr. Spock....

Everybody seems to compare it to a car on a treadmill... it's not the same...

Planes take off with ski's, on water, hell.... VTOL is available so they don't even need to move at all.

Basically... the wheels are there only to make it easier to roll on the ground to achieve the "AIR" speed necessary to fly.

Since the wheels are not propelled, the conveyor will have absolutley NO effect on the planes body.

The ONLY way it could stop the plane is if the conveyor speeds up, melts the wheel bearings and locking up the tires. But if the engines have enough thrust, it'll still take off smoking the tires all the way down the runway.

Ofcourse... if the treadmill were programmed to match the speed of the wheels.... it would instantly accellerate to infinity, creating a massive gravitational field, collapsing in on itself and creating a singularity that'll eat the entire planet.:biggrin:

Givin Mythbusters love to destroy stuff, they couldn't hope for a better way to end a show.

Launch Photon Torpedoes too why ur at it. My guess is that it would not fly. Ur basically securing a huge rope to the tail of the plane preventing it from accelerating to a point where the wind passing over the wings will create the lift required to make the plane fly. So no I dont think it will fly. Now thats my opinion based on what was posted in the first post.

 

[Madcat455]

Ah, but look at this:
"Imagine a plane is sitting on a massive conveyor belt, as wide and as long as a runway. The conveyer belt is designed to exactly match the speed of the plane, moving in the opposite direction."

According to the above, your forward motion would be instantly negated by the opposite direction of the treadmill.

NO... according to that, the treadmill would accellerate, doubling the speed of the wheels, but not negating the force of you pulling on the rope, or your friend pushing you, because those forces operate outside the effectivness of the treadmill.

The treadmill can ONLY effect the tires.. they'll spin faster, but won't stop the plane.

 

[Pitbozz]

Launch Photon Torpedoes too why ur at it. My guess is that it would not fly. Ur basically securing a huge rope to the tail of the plane preventing it from accelerating to a point where the wind passing over the wings will create the lift required to make the plane fly. So no I dont think it will fly. Now thats my opinion based on what was posted in the first post.

There is nothing preventing the plane from moving. The treadmill is irrelevant.

 

[Pitbozz]

NO... according to that, the treadmill would accellerate, doubling the speed of the wheels, but not negating the force of you pulling on the rope, or your friend pushing you, because those forces operate outside the effectivness of the treadmill.

The treadmill can ONLY effect the tires.. they'll spin faster, but won't stop the plane.

 

[UNGN]

Mythbusters....the same guys who busted the driveshaft dropping myth. Somebody better tell NHRA that nothing happens when a car drops the front part of the driveshaft.

They actually got a car to pole vault, comfirming that it could happen.

They busted the myth that you could tie a chain to the rear axle and drive the car away, leaving the axle in place. You can, but you have to cut through the lower control arms first to do it.

 

[SouthernCal GN]

There is nothing preventing the plane from moving. The treadmill is irrelevant.

The wheels and suspension are part of the plane- you can't separate the two. I'm just using the original post, and assuming nothing. Treadmill, lap pool, dyno- all involve opposing forces that work to keep an object stationary. The conveyor is moving at the exact speed of the aircraft, thereby negating forward motion.

There is no forward motion- there is no lift. Basic aerodynamics.


There is no spoon.

 

[Pitbozz]

The wheels and suspension are part of the plane- you can't separate the two. I'm just using the original post, and assuming nothing. Treadmill, lap pool, dyno- all involve opposing forces that work to keep an object stationary. The conveyor is moving at the exact speed of the aircraft, thereby negating forward motion.

There is no forward motion- there is no lift. Basic aerodynamics.


There is no spoon.

Negative, ghost rider! The wheels and treadmill are irrelevant. The plane is engine driven, not wheel driven. The plane will accelerate and move forward and takeoff.

Look at my rollerblade reference.

 

[Brer Rabbit]

Maybe Im misunderstanding the question then.

There is nothing preventing the plane from moving. The treadmill is irrelevant.

How is treadmill irrelevant. It is the reason why the plane is not moving forward, right? The treadmill will accelerate in the direction that would prevent the plane from moving forward at all, the instant the treadmill cant keep up is the only point where the plane will move forward creating the wind over and under the wings necessary for lift. GOD I LOVE THIS TOPIC!

 

[SouthernCal GN]

"Negative, ghost rider! The wheels and treadmill are irrelevant. The plane is engine driven, not wheel driven. The plane will accelerate and move forward and takeoff.

Look at my rollerblade reference."


Correct- the plane IS engine drive. Therefore, the wheels have no limiting factors (gears, engine drag, etc) to hinder their rotation. They will rotate at whatever speed the conveyor is moving at.

As the wheels are attached to the aircraft, they are relevant. The rotation of the conveyor will absorb whatever forward motion is created by the engine, and the plane will not move.

No movement- no generated lift- no flight.

 

[Brer Rabbit]

Thats not what the original post stated.

Negative, ghost rider! The wheels and treadmill are irrelevant. The plane is engine driven, not wheel driven. The plane will accelerate and move forward and takeoff.

Look at my rollerblade reference.

"The conveyer belt is designed to exactly match the speed of the plane, moving in the opposite direction" Cut and pasted from the original post.

 

[notacarlo]

My brain hurts.

Think about this....if you suddenly turn the conveyor 90 degrees the plane will crash without leaving the ground or accelerating......:biggrin:

It will on the other hand be several hundred yards to the right of where it started.

Ahh, the Polish logic.

 

[83hurstguy]

A plane generates lift by moving air over its wing surface- forward motion is made by the powerplant generating thrust enough to overcome drag.

Your car strapped to a dyno (or you on a treadmill) generates no forward motion- the potential forward motion is counteracted by the action of the rollers (or tread). Since the conveyor belt is "exactly matching the speed of the aircraft" there is no forward motion; hence, no lift is generated.

gut your trunk and put a jet engine into it. Strap it to the chassis dyno. no matter how fast the dyno spins your wheels backwards, you'd better say a prayer that the tie down straps are strong enough or your car is going for a ride.

Put on rollerblades, and have a friend push you up the treadmill. If you have an external force acting on the system, the wheels and belt speed are irrelevant. If you have something holding you in place on the treadmill, whether the belt moves at 10, 20, or 200 mph, you aren't going anywhere.

Get the point yet? Just look at force pairs. Wheels drive a car, force vectors points backwards from the wheels, chassis dyno provides equal and opposite reacting force to keep car stationary. Airplane engines use thrust against the atmosphere to push forward... you'll need something that counteracts that to stop it...

This is only coming from somebody currently working on their MSME, so take it for what it's worth...

 

[83hurstguy]

oh yeah, and to instantaneously match speed of the aircraft, you'll calculate an infinite acceleration in the conveyor belt, which means it will virtually self destruct and cease to exist.

Problem solved.

 

[SouthernCal GN]

oh yeah, and to instantaneously match speed of the aircraft, you'll calculate an infinite acceleration in the conveyor belt, which means it will virtually self destruct and cease to exist.

Problem solved.

As we're in the world of theoreticals, that self destruction clause is negated.

Hey, I didn't pose the question- I'l just looking at it from twisted angles!