conveyor belt and plane answered at last ??

[Deleted member 63160]

Very good mitch I see you are a fast learner

When the plane reaches 85knots or about 97.816mph the plane will take off.

Now assuming the conveyor is doing the same the wheels are doing 185.632 mph at take off.

Back to the question The speed of the Conveyor matches the speed of the planes wheels

Think we may have a problem.

Not really. At take of the plane is doing 85 knots. The belts speed relative to the wheels however is 170knots which complies with the bit you highlighted.

 

[Deleted member 63160]

Lets call wheels A. Belt B. If A is moving away from B at 170 knots then B is moving away from A at the same speed, 170 knots. There speed is relative to each other. Therfore the speed of A realative to B is equally matched at take off.

 

[doitall]

No Mitch.

If the conveyor is doing 97.816 mph and the plane is doing the same (85knots) then the wheels must be turning twice as fast as the belt. 195.632mph.

This conveyor belt has a control system that tracks the aircraft's wheels speed and tunes the speed of the conveyor belt to be exactly the same as the wheels, but in the opposite direction.

 

[Deleted member 63160]

No Mitch.

If the conveyor is doing 97.816 mph and the plane is doing the same (85knots) then the wheels must be turning twice as fast as the belt.

This conveyor belt has a control system that tracks the aircraft's wheels speed and tunes the speed of the conveyor belt to be exactly the same as the wheels, but in the opposite direction.

I'm confused. It says the conveyor tracks and matches the speed. Not travels at half the speed. As the wheels are non driven theres no reason why this couldn't be the case when the plane's blowing along at 85.

 

[Deleted member 63160]

If the conveyor is doing 97.816 mph and the plane is doing the same (85knots) then the wheels must be turning twice as fast as the belt. 195.632mph.



TBH if the belts moving away from the plane at 170knots and the wheels are attached to the plane, the belts doing 170 knots away from the wheels. Same speed as the wheels which are attached to the plane are doing from the belt.
Are you perhaps thinking of the wheel and belt speed differential in rpm perhaps.

 

[doitall]

Fact Mitch.

If the belt is going 10mph and the plane on the belt is also moving at 10mph in the opposite direction, then the wheels must be doing to combined total (20pmh)

Can you see the problem.

Tunes the conveyor belt to exactly the same speed as the planes wheels.

It's impossible to do, it the plane and belt are moving in different directions the wheels will always be the combined sum

 

[doitall]

Put it another way, if the belt is doing 10mph, and the plane is stationary the wheels will be matching the belt speed, but the plane has to go 10mph faster to match the belt, so the wheels are now doing 20mph.

 

[libby lou lou]

What size are the wheels.

 

[securespark]

Dunno. But the main wheels are bigger than the front one.

 

[doitall]

Doesn't matter what size the wheels are the ground speed will be the same.

 

[libby lou lou]

To have something running twice as fast must have ratios, so wheel size must matter?.

 

[doitall]

No Libby.

the conveyor is moving at 10mph so if you stand a dustbin on the belt it will also be going at 10mph.

Now stand the wheel on the conveyor and it will also go 10mph, next hold the wheel so it is turning on the spot, the belt it is stood on will be going under the wheel at 10mph, so if you stick a speedo on it, it will show 10mph.

In addition to that we now want the wheel to move forward at 10 mph, therefore the speedo will record 20mph.

If you mark a starting line, after 1 hour the belt will have gone 10mile on way and the wheel 10 miles the other or a combined distance of 20miles.

 

[UriBentMySpoon]

Don't be obtuse Uri - the wheels have nothing to do with it - they just spin at twice the speed. Newton's law governs the engine thrust. Fook all to do with the wheels, they can do what they like.

I didn't mention the wheels. I was proposing that the speed the conveyor belt backwards matched exactly the speed of the Jet moving forwards.

Plane stands still from an observers point of view off the conveyor belt.

 

[joe-90]

Don't be silly, that would only be true if the conveyor took the atmosphere with it. The engines apply forward thrust as per Newton, and the plane goes through the air and takes off - fook all to do with wheels or belts.

 

[UriBentMySpoon]

Don't be silly, that would only be true if the conveyor took the atmosphere with it. The engines apply forward thrust as per Newton, and the plane goes through the air and takes off - fook all to do with wheels or belts.

The forward thrust projects the plane along the ground. The ground in this case is the conveyor belt. The plane moves at one mph forwards, the belt 1 mph backwards. forward motion to the observer standing away from the belt is effectively cancelled out. In response to Newtons Law, the plane is moving along the conveyor belt.

Assuming no winds the plane is not moving through the air, no pressure created, no lift.