## Re: [ksurfschool] Kite depowering ratio

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• Hi Hung & anyone interested, I posted something about this on the KSurf list. In short: The interesting thing to me was that the C Quad loses efficiency
Message 1 of 2 , Dec 17, 2000
Hi Hung & anyone interested,

The interesting thing to me was that the C Quad loses efficiency
(lift-to-drag) when it's "powered up" more than the AR5. In other words, the
AR5 can sheet in and out quite a ways before the L/D starts to suffer, while
the C Quad is definately most effecint at its lowest power setting.

But if you really want to split hairs, the highest lift-to-drag ratio on the
AR5 was at about 20% bottom line tension. So if you weree trying to go
absolutely as fast as possible you'd want to use the size that gave you the
right amount of power at top speed with the kite mostly sheeted out. But the
difference would be small compared to most kites.

Mark Frasier

----- Original Message -----
From: "Hung Vu" <hungvu@...>
To: <ksurfschool@egroups.com>
Sent: Saturday, December 16, 2000 6:32 PM
Subject: [ksurfschool] Kite depowering ratio

> Finaly, I managed to find some time to quickly go through the kite test
> report from Andrew J Reid at
> http://www.peterlynnkites.com/web/information/testrept.htm. The report
> is excellent; however, it contains quite a bit more info than most of us
> "mortal" kitesurfers would want to know.
>
> There is one element of the report discussing the kite depowering ratio
> of various kites which could be useful in selecting kite size. The
> report shows the AR5 has a depowering ratio of 1.8, C-quad of 1.6 and
> Waterfoil of 1.3 (the higher the number, the more one can depower the
> kite).
>
> What these number mean is that if you already has an AR5 of a certain
> size, the projected surface of the next AR5 kite you should get should
> be roughly 1.8 of the projected surface of the current kite.
>
> For example:
> Current kite Next size up kite
> 5.5 (projected 3.4) projected 6.1. The best is 11.5 (projected 6.4)
> 7.5 (projected 4.4) Projected 7.9. The best is 13.5 (projected 7.4)
> 9.5 (projected 5.4) Projected 9.7. The best is either 15.5 or 20.5?
>
> These "formula" seem to agree with my experience with the AR5s (I have
> an 5.5 and 11.5). I am not so sure about the C-Quad and the Water Foil.
>
> P.S. the depowering ratio of 1.8 could be a bit "low" for the AR5 as the
> author did not test the full power range for the AR5.
>
> Hung.
>
>
>
>
>
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