air extractor for asw19 and asw20

Curious what you mean by "how well it works". The theoretical small performance improvement will be very difficult to measure if possible at all. Or do you refer to the reduced cockpit noise?

Ramy

The purpose of the extraction vent is to increase the available airflow to the cockpit. The ASW-19 has NACA vents under the wing roots to draw air in, but there is no clear path for it to exit. The extraction vent, and modification of the bulkhead to allow airflow, gives the air someplace to go and reportedly greatly increases the comfort level in the cockpit. Noise reduction is primarily due to being able to keep the canopy vent closed and a reduction of "pressurized" air leaking under the canopy seals.

Any performance benefits are a bonus in my book and not a serious consideration unless you are a hard-core performance tweaker looking for every .1% gain.

Paul A.

On Tuesday, October 17, 2017 at 1:12:58 PM UTC-4, Paul Agnew wrote:
The purpose of the extraction vent is to increase the available airflow to the cockpit. The ASW-19 has NACA vents under the wing roots to draw air in, but there is no clear path for it to exit. The extraction vent, and modification of the bulkhead to allow airflow, gives the air someplace to go and reportedly greatly increases the comfort level in the cockpit. Noise reduction is primarily due to being able to keep the canopy vent closed and a reduction of "pressurized" air leaking under the canopy seals.

Any performance benefits are a bonus in my book and not a serious consideration unless you are a hard-core performance tweaker looking for every .1% gain.

Paul A.

Some experience on this topic(about 80 sold for 9 types)leads me to comment..
1) Extractors can and do help ventilation(and removal of exhaled moisture). They are a big improvement in 19's and 20's, maybe a bit less so in ships with better ventilation to start with.
2)Sealing the cockpit area off from the aft fuselage has a meaningful effect on this extraction by increasing the pressure differential between the cockpit and ambient. Without sealing, the pressure reduction is limited by air coming from the rudder horn and hinge area that is low pressure, but not as low as the vent.
3) Canopies leak. It is better to have the leak be into the cockpit and not out over the wing root area. Commonly one of the noises heard is air being sucked in around the edges of the little vent window.
4) The extractor shown may well infringe on the patent applied for by JS or their resources.

FWIW- Hard core performance guy.
UH

Not having seen the JS patent application, but cockpit air extractors have been in the public domain for a while now. Unless JS has something unique (perhaps the little airfoil in the middle), and unless they filed their patent before selling the first JS1 with an air extractor, JS is not likely to be granted a patent for the air extractor on the JS1c. The JS-3 extracts air out the underside of the fuselage. The JS-3 air extractor is new and I suspect that is what their patent is for.

On Friday, October 20, 2017 at 7:21:04 AM UTC-7, wrote:
On Tuesday, October 17, 2017 at 1:12:58 PM UTC-4, Paul Agnew wrote:
The purpose of the extraction vent is to increase the available airflow to the cockpit. The ASW-19 has NACA vents under the wing roots to draw air in, but there is no clear path for it to exit. The extraction vent, and modification of the bulkhead to allow airflow, gives the air someplace to go and reportedly greatly increases the comfort level in the cockpit. Noise reduction is primarily due to being able to keep the canopy vent closed and a reduction of "pressurized" air leaking under the canopy seals.

Any performance benefits are a bonus in my book and not a serious consideration unless you are a hard-core performance tweaker looking for every .1% gain.

Paul A.

Some experience on this topic(about 80 sold for 9 types)leads me to comment.

IIRC (and I could be wrong) didn't the Mandl Extractor with DG predate Jonkers? At one point the Mandl was advertised as "patent pending" as well....

On Friday, October 20, 2017 at 11:17:05 AM UTC-4, Jonathan St. Cloud wrote:
Not having seen the JS patent application, but cockpit air extractors have been in the public domain for a while now. Unless JS has something unique (perhaps the little airfoil in the middle), and unless they filed their patent before selling the first JS1 with an air extractor, JS is not likely to be granted a patent for the air extractor on the JS1c. The JS-3 extracts air out the underside of the fuselage. The JS-3 air extractor is new and I suspect that is what their patent is for.

JS mention of patent application as mentioned on their web site was for the incorporation of airfoil shaped additional element in the outlet area.
UH

On Friday, 20 October 2017 17:21:04 UTC+3, wrote:
4) The extractor shown may well infringe on the patent applied for by JS or their resources.


Haha, you are taking about factory that "borrowed" ASH26 fuselage and added Ventus-2 wing geometry to create JS1.

You mean the JS1 wing that differs in aerofoil, plan form, dihedral, winglet and structure from the Ventus 2 - that in fact shares no design features with it at all.

Ok, probably all similarities are purely coincidental then.

But regarding air extractors, I find it surprising that mainly US audience of ras does not mention Will Schuemann's work, predating JS or DG, what 35-40 years?

On Saturday, October 21, 2017 at 2:58:33 AM UTC-4, krasw wrote:
Ok, probably all similarities are purely coincidental then.

But regarding air extractors, I find it surprising that mainly US audience of ras does not mention Will Schuemann's work, predating JS or DG, what 35-40 years?

Wil was certainly a pioneer. IIRC, his 301 Libelle captured ventilation air using the leading edges of the gear doors as a scoop (the belly just ahead of the doors was flattened a bit so the doors protruded--probably not the best idea in the event of a gear up landing).

Thus pressurized, the gear box fed ventilation air into the cockpit through two outlets over the shoulders of the pilot. I don't think these could be modulated, at least initially, which was a problem when it got cold.

Air exited the glider at the base of the rudder through an expanded opening and "splitter" at the bottom of the rudder based on Wil's experiments to find the ideal low-pressure location. Jim Indrebo had a really nice version of that exit vent on his 301 in the early 80s.

Chip Bearden