I fly in the North Island of New Zealand where average cloud bases are
4500-6500ft
range and with quite a lot of high ground and sea breezes from both coasts
so
the low to mid performance range is where 95% of the flying is .
I fly at max cockpit weight as well so I am looking to improve the lower
range and I can
forget the water as I can't put much on unless I fly over gross weight. I am
not a test pilot
and do not intend to be one.
The winglets on 15m make a difference ,the reasoning about this idea is
perhaps cut the
extention at the the point where the control surface ends and basically flip
that 300mm
on each end to vertical and reshape to a winglet.
The broad paddles at the wingtip of the extention from past history of
wingtip improvements
will gain the most.
With the present state of winglet developement I think that the improvement
could be
quite considerable.
Take the base performance of the 15m plus 1 metre of extention and then the
winglet
with one of the latest design concepts (latest designs recording 1.5-2.5 LD
points improvement)
The better handling is the cream, that is where the idea of 44-45 LD seems
reasonable .
You don't reinvent the wheel therefore the question ,"has anyone done this
before"?
gary


"Andreas Maurer" wrote in message
...
On Fri, 17 Sep 2004 14:24:32 +0200, "Bert Willing"
wrote:

Well, the ASW20 with 15m and winglets has been measured to 41:1, and I
honestly don't think that an additional meter in span will bring you 3-4
points (the difference between ASW20 15m and 16.6m ist just one point).
Apart from that, I haven't heard of any ASW20L with winglets fitted onto
the
extended span, and you probably would have to contact Schleicher to get
their ok.

Performance spread is huge for the ASW-20 - the 20L of my club had
(with 15 meters) at least identical performance as Ventus C and LS-6
(the LS-6 in question was regared as one of the best LS-6 around). We
estimated its L/D to rather 43:1 than 41:1 (based on many team flights
with very good pilots).

It easily outclassed the (re-finished) 20 of our neighbourhood club,
even at high speeds (180-200 kp/h) when the latter carried much more
water (60 Liters vs. no water).

On the other hand: I usually flew the 20 without wingtips. Performance
gain with the 16.60m wingtips was only below 110 kp/h and water
ballast was not possible, therefore in my opinion overall performance
was always better without wingtips, even on weak days (average climb
less than 200 ft/min) - I would not invest a single cent in the
modification of the extended wingtips.





Bye
Andreas