Hank Nixon built the ASW24/W27/W28/G29 kits now approved by Schleicher at his
shop in New Jersey. It can be found on USA Schleicher rep John Murray's website.
http://www.easternsailplane.com/eastern/eastern.php/EasternSailplane/TheVent
I had theNixon/Murray/Butler ventinstalled in the 27. The same shop has
installed the kit in an LS8.
The kit has a large removable funnel which slots into the vent and covers the
baggage compartment (yet a 6 litre MSR Dromedary Bag still fits).Doubt it does
anything for technical performance, but the air flow through the cockpit is
greatly improved. The dark side, negative pressure will find anywhere that the
cockpit isn't sealed and pull cold outside air in. Now we've used the
Streifeneder canopy seal mod (4mm x 0.5mm silicone tubing in a routed slot
around the canopy) and it's one of the best sealed gliders I've flown.
As Mike pointed out, these ideas have been around for a while. Nimbus 3 ex-
VH-VJS had an exhaust vent in the bottom of the rudder, which I thought was a
Wil Scheuemann designed mod. Believe it worked well... Never tried flying with
the exhaust taped up.
The least expensive vent mod is the Quiet Vent by John "Bumper" Morgan.
Adheres to the inside of the vent in the canopy window, smoothing the airflow
and cutting down on noise. Works well in conjunction with the exhaust vent, and
installs in a minute.
For a laugh, look at the Eastern Sailplane catalog pages, click "Sailplanes".
You can add ASG29s, ASH30s, etc to your shopping cart with a "buy now" button.
Jim
________________________________
From: "[email protected]" <[email protected]>
To: Discussion of issues relating to Soaring in Australia.
<[email protected]>
Sent: Tuesday, June 5, 2012 4:32 AM
Subject: Re: [Aus-soaring] Mandl extractor - Is it snake oil or is there
something to it?
Hi Mike and others!
It wasn't only Wil Schuemann who experimented with an air outlet. About 25
years ago Dick Buttler worked with Schleicher to fit
an air extractor to his ASW 22. Martin Heide put an air outlet (similar to the
Mandl device) on the undercarriage door of his
ASH 25 prototype but was unable to measure a pressure difference in the
cockpit. This undercarriage door is currently in my
workshop in Adelaide.
The US Schleicher agent has developed an air extractor for the ASG 29 in close
cooperation with Michael Greiner, the designer
of the aircraft. It feature a rather substantional funnel which is designed to
accelerate the cockpit air prior to entering the free
airstream. By doing so the turbulence around the air extractor is reduced and
the drag is supposed to be minimised.
The big question is whether the drag created by the turbulence around the air
extractor is less than the drag caused by the escape
of air around the canopy frame. In any case, a performance gain of anywhere
near four L/D points is totally unrealistic. If only half
true the LS10 would win every competition .......
I hasten to add that cockpit ventilation is likely to be improved as the
ventilation air can escape without finding its way through
the tail boom to the rear of the fuselage. That in itself is an advantage -
especially in a country like Australia.
Kind regards to all
Bernard
>----- Original Message -----
>
>From:
"Discussion of issues relating to Soaring in Australia."
@lists.internode.on.net>
>
>To:"Discussion of issues relating to Soaring in Australia."
>
>Cc:
>
>Sent:Tue, 05 Jun 2012 18:13:59 +1000
>
>Subject:Re: [Aus-soaring] Mandl extractor - Is it snake oil or is there
>something to it?
>
>
>At 04:40 PM 5/06/2012, you wrote:
>
>Not sure about independent, but
Jonker does the same thing for their
>>JS1's, and I've heard of experimental ASW20 mods to add one.
>>http://www.jonkersailplanes.co.za/index.php?pageid=36
>>
>>-Matthew
>>
>>
>No the JS-1 vent is not the same as the Mandl extractor although both aim
to suck exit air out through a low pressure point. The Mandl device is on
the bottom of the fuselage and looks to be in around the trailing edge of
the wing location in the fore and aft sense. The JS-1 vent is on top of
the fuselage not far aft of the canopy and it has a little wing in it to
get the air to flow along the surface better. The JS-1 location is likely
a lower pressure area (top of wing and fat part of fuselage) than the
lower fuselage lined up with the wing TE where the pressure is
about back to static pressure. Also the Mandl extractor doesn't seem to
try to flow the exit air parallel to the airstream. Some tests with dye
or tufts would be interesting as well as static pressure measurements.
Don't forget also if you manage to put the vent in a low pressure area
and close the inlet, cockpit pressure will be a fair bit lower than
outside - maybe up to 100 feet or so altitude equivalent with consequent
effects on the pressure altitude measured by your logger.
>
>This is by no means a new idea to have an exit vent. Wil Schumann used
the back of the gear doors as an extractor on his H301b Libelle. I had an
exit vent on my Mini Nimbus in 1978. Gliders are coming out with better
cockpit ventilation nowadays It took long enpough. failure to provide
adequate ventilation in the cockpit is like failing to provide proper
cooling for the engine in a powered aircraft.
>
>Mike
>
>Borgelt Instruments- design & manufacture of quality soaring
instrumentation since 1978
>www.borgeltinstruments.com
>tel: 07 4635
5784 overseas: int+61-7-4635
5784
>mob: 042835
5784
:
int+61-42835 5784
>P O Box 4607, Toowoomba East, QLD 4350, Australia @lists.internode.on.net>
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