Air extractor for sustainer and motor gliders?

On Tuesday, August 25, 2015 at 1:41:15 AM UTC-5, Tango Whisky wrote:
Am Montag, 24. August 2015 23:53:39 UTC+2 schrieb Jonathan St. Cloud:
On Monday, August 24, 2015 at 12:43:49 PM UTC-7, wrote:


Look at the Jonker Sailplanes website for one example


The poster was looking for solutions that would work in gliders with fuel tank in baggage compartment. The JS-1 has a take on the Buttler/Murray/Nixon vent which would not work with a gas tank were the vent would be.

I have put extractor vents into the small engine bay doors on my Ventus cM. Needed to put two 5 cm dia holes into the bulkhead separating the cockpit from the engine bay (Schempp-Hirth confirmed me that this bulkhead is not structural and that I could put any holes I'd like).

Aside from the questionable Mandl report on the DG website and anecdotal evidence from those who had air extractors installed - are there measurable effects? While I believe that venting of the cockpit is improved, I doubt this is making for better performance until someone shows me data. Until then, I would call this snake oil.
Herb

At 13:59 25 August 2015, wrote:
On Tuesday, August 25, 2015 at 1:41:15 AM UTC-5, Tango Whisky wrote:
Am Montag, 24. August 2015 23:53:39 UTC+2 schrieb Jonathan St. Cloud:
On Monday, August 24, 2015 at 12:43:49 PM UTC-7,
wrote=
:
=20
=20
Look at the Jonker Sailplanes website for one example
=20
=20
The poster was looking for solutions that would work in gliders with
fu=
el tank in baggage compartment. The JS-1 has a take on the
Buttler/Murray/=
Nixon vent which would not work with a gas tank were the vent would be.
=20
I have put extractor vents into the small engine bay doors on my Ventus
c=
M. Needed to put two 5 cm dia holes into the bulkhead separating the
cockpi=
t from the engine bay (Schempp-Hirth confirmed me that this bulkhead is
not=
structural and that I could put any holes I'd like).

Aside from the questionable Mandl report on the DG website and anecdotal
ev=
idence from those who had air extractors installed - are there measurable
e=
ffects? While I believe that venting of the cockpit is improved, I doubt
t=
his is making for better performance until someone shows me data. Until
the=
n, I would call this snake oil.
Herb


http://www.jonkersailplanes.co.za/airextractor.htm

No raw data, but you could always ask them?

Shaun