Air exit vent with engine box?

On Thursday, November 19, 2015 at 10:01:49 PM UTC-5, Jonathan St. Cloud wrote:
Was wondering if anyone has figured out a good air exit vent for a glider with an engine box i.e., ASG-29E, ASW-28E, ASW-24E, Nimbus 4T...

The producers of the ES Vent, which is commonly installed in 24's, 27's, 28's, and 29's, as well as a hand full of other types, have looked at the issue of installing a vent using the design principles that work well in the above in the 29E and similar gliders. All of the Schleicher motorized gliders that have fuel tanks in the baggage compartment share 2 issues.
1. The aft bulkhead in the baggage compartment is a bit too far forward to allow placement where experience with the other similar types shows it should be. This would require a very special vent that would have to have alteration to the bulkhead. This is something we do not think is wise as it is important structure. Even if we could engineer this, and get approved by the factory, the installation would be very complex.
2. To create a collector to lead into the vent smoothly would require alterations to the fuel tank. We aren't going to do that for reasons described above.
As of this time we do not yet have a practical solution for these gliders.
UH

What are the draw backs of using the DG Mandel type air exit as this seems more viable than the ES style vent?

On Saturday, December 5, 2015 at 4:02:20 PM UTC-8, wrote:
On Thursday, November 19, 2015 at 10:01:49 PM UTC-5, Jonathan St. Cloud wrote:
Was wondering if anyone has figured out a good air exit vent for a glider with an engine box i.e., ASG-29E, ASW-28E, ASW-24E, Nimbus 4T...

The producers of the ES Vent, which is commonly installed in 24's, 27's, 28's, and 29's, as well as a hand full of other types, have looked at the issue of installing a vent using the design principles that work well in the above in the 29E and similar gliders. All of the Schleicher motorized gliders that have fuel tanks in the baggage compartment share 2 issues.
1. The aft bulkhead in the baggage compartment is a bit too far forward to allow placement where experience with the other similar types shows it should be. This would require a very special vent that would have to have alteration to the bulkhead. This is something we do not think is wise as it is important structure. Even if we could engineer this, and get approved by the factory, the installation would be very complex.
2. To create a collector to lead into the vent smoothly would require alterations to the fuel tank. We aren't going to do that for reasons described above.
As of this time we do not yet have a practical solution for these gliders..
UH

On Sunday, December 6, 2015 at 5:53:04 PM UTC, Jonathan St. Cloud wrote:
What are the draw backs of using the DG Mandel type air exit as this seems more viable than the ES style vent?

Is it worthwhile fitting a vent unless the particular vent design and location are proven to be effective for your glider type? There is a little article on the JS website about the design of their one.

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

On Sunday, December 6, 2015 at 12:53:04 PM UTC-5, Jonathan St. Cloud wrote:
What are the draw backs of using the DG Mandel type air exit as this seems more viable than the ES style vent?

It very much depends on whether there is a low pressure area on the fuselage that will provide the suction needed to be effective. If there is, the next issue is whether it is in a place where the structure will permit installation as well as being able to provide and install the inner portions of the system that bring the airflow smoothly up to free stream speed.
I repaired 2 holes in a Discus 2 resulting from 2 failed attempts.
UH

Flew with a high-tech mod today:
A (dry) sponge from my washing kit jammed into the collector of the Uncle Hank exhaust in the 29.
At one point wanted some ventilation. (Never did get to the freezing level.)
Discovered that the air vents don't work very well with the exhaust plugged.
Jim

On Sunday, December 6, 2015 at 9:51:27 PM UTC-8, JS wrote:
Flew with a high-tech mod today:
A (dry) sponge from my washing kit jammed into the collector of the Uncle Hank exhaust in the 29.
At one point wanted some ventilation. (Never did get to the freezing level.)
Discovered that the air vents don't work very well with the exhaust plugged.
Jim

But it was so quiet, you didn't notice the wheel was still downt. ;-)