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
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