On Jun 10, 11:50*pm, sisu1a wrote:
Hi Chris.
I've made only one modifcation to my Speed Astir. *It's *a 'Mandl
Extractor' vent to let air out. *Subjectively, I know I'm a lot cooler
in the cockpit. *I haven't done this yet, but here's what I'm going to
do to verify my subjective observation. *I have set up a water
manometer that indicates the difference between cabin pressure and the
static system. *I'll fly with my Extractor in place, but with the
inside opening taped over. *After noting the manometer at 2 or 3
airspeeds/alititudes, I'll climb back up and repeat, after ripping the
tape off the extractor. *I don't expect spectacular numbers, but if it
just confirms a small drop in cabin pressure relative to the static
system, I'll continue to use it. *If it indicates my 'subjective'
observations are wishful thinking, I'll... still use it because I
THINK it works (even if I'm wrong!)

I also made a Mandle Exctractor, (as well as a Butler Extractor, which
is what I actually use on my SZD-59 although the Mandle I made works
just fine too... both really provide a night and day difference
compared to no exhaust exit, but have made no real measurements as to
actual performance...) and if Fuzz doesn't feel like molding up some,
I would be happy to. In the process of researching different aspects
on the subject, I made some discoveries and added some refinements as
well to the inlet of this outlet, to efficiently accommodate a
honeycomb grill of strategic proportions rather than putting a mere
piece of mesh there to 'keep out the critters' as DG/LS put it but did
not change the Mandle designed portion of it and of course it could be
easily made as a normal one by removing the bell-mouth inlet and
honeycomb flange...

Tomorrow when I have more time I will post my synopsis on the
subject...

-Paul

Please do, I am interested in making a replacement hatch for my Grob
also, but have no experience molding fiberglass.

Todd