On Sunday, August 23, 2015 at 5:47:29 PM UTC-4, wrote:
I reviewed this news group, Buttler/Nixon/Murray vent and DG's page on Mandl air extractor. Could not find a suitable reference for and extractor for a sustainer or motor glider. I did note that the open tails of DG and LS gliders apparently did not do a good job of extracting air, hence the Mandl, which according to comments on this news group does not good avery effective job either. Anyone come up with a good method of extracting air from a glider with a fuel tank in the baggage compartment?

What type of glider are you referring to?
John Murray and I have looked at the feasibility on many gliders.
Among those that have had variants of the ES vent are ASW-24,27,28,27-18, Discus B, Ventus B,Ventus 2B, LS-6, LS-8, DG400, Lak-17,Lak 17T, and Std Cirrus.
ASG-29E is on the horizon for this Fall.
Others are obviously possible, provided there is enough potential to justify the one time costs for a particular installation.
UH