Author Topic: New Cherub Owner  (Read 6809 times)

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Nick in Bristol

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Re: New Cherub Owner
« Reply #30 on: September 17, 2011, 11:32:52 AM »
Cheers Phil, will take a gander now.

Nick in Bristol

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Re: New Cherub Owner
« Reply #31 on: September 17, 2011, 11:47:16 AM »
Just read the "T foil rudders - a complete guide" and am definitely sold on the idea of a T-foil now!

One thing that immediately struck me is why just a single T? Would it make any sense to have an additional smaller (less prone to breakage during heeling) T closer to the surface to increase energy recovery but which should not interfere with the laminar flow deeper down for the displacement reduction.

Or is that me missing something crucial?

Offline phil_kirk

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Re: New Cherub Owner
« Reply #32 on: September 18, 2011, 09:52:24 PM »
As you will know the horizontal foil can be set at the bottom of the rudder or part way up it.
With the horizontal foil set part way up you can't raise the foil so high in the stock for launching and recovery.  That's the practical bit.

The science bit is that it is more efficient to have a larger single foil than 2 smaller ones. Less tip losses.
as an example we don't see many bi-planes these days and most modern hydrofoil craft avoid ladder foils (which have several lifting foils).

Cherubs being light appear to work best with the foil deep in the water. There is less need to recover energy from the wake because a cherub planes early and doesn't have much of a wake.