Question posed on Facebook

[Chas]

I'm making no comment!

 

[fbnss]

Is the plane moving?The wheels dont have anything to do with it. If the plane is moving forward through the air then yes?

 

[nick_the_fish]

only if it had a headwind of 160 kts...

 

[moggy1968]

No

 

[Towpack]

Yes.

 

[karl webster]

No

 

[chapel gate]

Yes, the wheels are not providing the forward motion for the plane, the jet engines are.

 

[Chris]

Absolutely. It's air speed over the wings. If it was a car and the belt matched the wheel speed then it would be like a rolling road and the car wouldn't move. But for a plane, it has no effect.

However, I should have said, that the wheels will now be spinning at twice the speed they normally would be

 

[chadr]

No.

The plane would be static relative to the ground and air around it, therefore no airflow over the wings and no "lift".

As an aside I would imagine the engines would overheat....

 

[StarCruiser]

Yes,
all as per Chris’s post above.

When do you give out the prizes Chas?

 

[Towpack]

It’s the thrust from the jet engines moving air backwards that move the plane forward relative to the air around it, generating lift. Whatever the wheels are doing is irrelevant.

 

[Aeronick]

As already told... jet engine are not connected to the tyres, they accelerate the air without decrease the pressure... in this way they provide a forward force!

The important thing to fly is the relative wind... wind speed + aircraft speed!

When the relative wind is fast enough the wings are able to provide lift!
The lift is created by a different speed between the upper and lower side of the wing.
In the upper side the flow is faster so has a lower pressure and on the lower side the flow is slower and has a higher pressure.
This difference in pressure permit aircraft to fly!

In all this... wheels aren't interested!!

 

[Shayne]

I say no because the jet would not actually start moving at all so even at full thrust it would remain grounded with no aerodynamics to assist lift .

 

[SeaJay]

yes, the hard part to answer would be at what speed would the wheels turn? the plane would be moving in a fwd direction with its turbine propulsion, but as the wheels turn to match direction of thrust the conveyor would follow, so the wheels would be starting and stopping to turn, or perhaps turning at 50% air speed of jet... this equation is one that needs Sheldon Cooper to explain

 

[StarCruiser]

... this equation is one that needs Sheldon Cooper to explain

Or Chas…

 

[Aeronick]

I say no because the jet would not actually start moving at all so even at full thrust it would remain grounded with no aerodynamics to assist lift .

It's impossible to obtain really what is written!
Whatever you do with the wheel, the jet engine is pushing forward so the speed of the wheel will be higher than the conveyor belt...
If the engine force is moving the plane at 10 kts and the conveyor speed is 10kts opposite direction the wheels will turn at 20kts!
What is written is fisically impossible to obtain!
Also if you run the conveyor at 100kts, the plane still going forward at 10 kts...so the wheels run at 110kts...
The moving of the plane is in respect to the air... it doesn't matter on the ground/ wheels etc

 

[StarCruiser]

The only problem I see would be holding the plane as the engines are revved as this is usually done with the brakes on for a sort of racing start. That said the plane would still take off, it would just have a rolling start.

 

[Aeronick]

The only problem I see would be holding the plane as the engines are revved as this is usually done with the brakes on for a sort of racing start. That said the plane would still take off, it would just have a rolling start.

The reason why they (sometimes) use brakes at the beginning is just to maximise the trust from the beginning in order to use less runway possible... in reality it's not changing a lot!
And taking in account what is written you can do also that because with the brakes the wheels are stacked so also the conveyor it's!
As soon as the engine is pushing forward the speed of the wheels will be higher the the conveyor one! Independently from the conveyor speed!

 

[StarCruiser]

Good point Marco. In exactly matching the speed of the wheels, at stop with brakes on the conveyor isn’t moving so brakes would hold it.

 

[Aeronick]

Think to be on the conveyor using roller blade! In order to go forward you use your arms... do you pay care in the conveyor speed? really not and the roller blade wheels are faster than the conveyor... in any case!