Thread: Answer to the aeroplane problem on Facebook

Yes.

- Would be a wonderful Training Aid for helogobuzzer Drivers.

Originally Posted by superquag

My error. That was a partial quote from the link posted. Anyway, this "problem" has been floating around for yonks, since last Century from memory. - Never quite satisfied myself with the answer - until I gained my Wings a few years ago.
(Spending the kids' inheritance )

Nevertheless, the 'plane takes off... with red-hot wheel bearings.

No it doesn’t... having wings obviously doesn’t require the ability to comply with conditions of an exam

If all points are to be met then the plane doesn’t take off.
Because it can not move.
The question renders the scenario invalid...

It’s NOT an Aviation question.
It’s a COMPREHENSION question.

Originally Posted by austastar

Hi,
Just rethink the problem to a real world scenario.
A float plane taking off against a current, and it all works.
Cheers

No it doesn’t.
In the real world the current doesn’t continually change speed to match “wheel” (or pontoon) speed.

It’s a Comprehension test, not a flight test.

Originally Posted by cuppabillytea

I thought this one had been done to death. The plane's wheels have nothing to do with how fast it can go. They only allow it to move across the ground. The only impediment to the plain achieving take off speed is the rolling resistance of the the wheels, which I would have thought would be negligible.

Not this one Billy... this is the Comprehension one.
If all conditions are to be met it is impossible.

Originally Posted by Ferret

Assuming wheel bearing friction is negligible then there are only 5 forces are acting on the plane.

1 Thrust from the engine - huge in any realistic aircraft engine.
2 gravity - constant but always directed down
3 lift - variable but always directed up
4 drag - variable, but always directed in the opposite direction to movement and therefore to thrust.
5 wheel rolling friction - very small compared to thrust from an engine but always directed in the opposite direction to wheel rotation

If the force of thrust is greater than the sum of the opposing forces of drag and wheel rolling friction then there is nothing on gods earth which will stop that plane moving forward, whether it is on a conveyor or not.

Since it moves forward the wings will generate a lift force. When the force of lift exceeds the force of gravity the plane will fly.

None of the above forces have anything to do with the conveyor. The conveyor can spin those wheels in any direction it likes, at pretty much any speed it likes within the bounds of reason. Provided thrust exceeds the sum of drag and friction losses associated with the wheel's movement then the plane moves and flies.

You forget #6...Rules...Aircraft are subject to rules.

In this instance to meet ALL the rules the outcome is impossible.

Originally Posted by Old Farang

Surely it has to depend on which direction the blades are rotating in relation to the turntable?

And if you have it on 45 or 33 1/3...

Originally Posted by Tombie

And if you have it on 45 or 33 1/3...

I'm old already. 78 is enough for me!

Put the helicopter on the conveyer belt and i bet it can lift off , Lol .