Expanded World Class

At 17:18 04 October 2007, Toad wrote:
On Oct 4, 12:35 pm, Eric Greenwell wrote:
toad wrote:
Bad idea to require suitability for early solo pilot.
This led to
unneeded 'dumbing down' of the design. Specific
features such as the
nose wheel and non-retractable landing gear. It
also leads to
sacrificing performance for easier handling.

I agree about the 'dumbing down' aspect, but performance
can be built in as mentioned in the Discus/LS4 rebuttal,
so it's performance disadvantage is to cut costs in
addition to 'dumbing down'.

Time to update your knowledge to at least the 1980s,
when the LS4,
Discus, and other gliders showed you don't have to
sacrifice performance
to have a glider with wonderful, forgiving handling.

--
Eric Greenwell - Washington State, USA

Then why doesn't the PW5 have better performance ?

As mentioned, due to cost/dumbing down (read fixed
gear).

Trade offs between handling and performance might be:
span, easier handling with lower span.
wing loading, high for performance, low for safety,
happy medium ?
airfoil and twist for better performance or stall
?
fixed gear vs retract.
high wing for safety vs lower drag mid wing ?

Actually a high wing is more efficient (I believe due
to better lift distribution). Don't believe me though,
find some technical reports by OSTIV and look at what
will probably be the newest Shleicher ubership. It
is called the MU: 31, and it is essentially a 27 (it's
fuselage is considered to be just about optimal, drag
wise, since it has to house a human and be crash safe
it is hard to get much better) with the wing moved
to the high position. The trailing edge actually terminates
on a pylon to maintain it's optimal hight at optimal
angle of incidence. It has -7 degrees of inboard washout
(wash-in?) in the first meter which gives it a strange
anhedral sort of look, and these nifty little dimples
in front of the wing/fuselage juncture to discourage
horseshoe vortecies. Due to these mods, it has 16%
less induced drag, and induced being 1/3 of total drag
has around a 5% lower sink rate than a normal 27, but
the high wing is said by them to be more efficient,
although admittedly it does not look as cool. If you
can't find anything on the MU: 31 and want to see it,
I can archive and link my scanned version of it I have
on disk. It really is cool.

All of these items can be optimized one way or the
other. The LS4/
Discus got a really good happy medium with both good
handling and
performance. If the PW5 had near the performance of
either of these
gliders, I would own a PW5, but the PW5 does not.

Todd

The PW-5's performance is not too bad, but it sure
ain't no looker. That is what I believe turns a lot
of people off the idea, when they can get a much cooler
looking ship for less money! I do think there ought
to be a one design ship though, but I would much rather
see the Sparrowhawk be it.

Paul Hanson
"Do the usual, unusually well"--Len Niemi