On 15 Oct, 15:54, Ian wrote:

Claiming I don't understand is rather futile. Of course, _I_ don't
understand. The point is you claim you do. So post the figures that
you base your understanding on and then I will share the same
understanding and this issue will be put to bed for good:

Can I assume that you have a rasonable base in fluid dynamics and
Kelvin-Froude actuator disk theory?

No, but I will be able to verify your formulas and check your maths
fine.

20kts of wind on the nose. Assume no friction or drag anywhere in the
system apart from the push backwards on the windmill. How fast does it
go. Show your workings.

You have given insufficient information.

Fine, make you own assumptions - just explain what the are when you
post the maths.