air extractor for asw19 and asw20

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.

4) The extractor shown may well infringe on the patent applied for
by JS or their resources.

FWIW- Hard core performance guy.
UH

I am buying one for my old ASW-19 which my brother now owns.
In emailing Alan, I mentioned the RAS patent infringement
musings.

Here is his response to that issue:

No patent infringement. My product was developed long before
Jonkers tried to patent their version and also uses different airfoil
sections, materials, technologies.

FWIW,

RO

Hopefully he had some documentation of that, evidence of construction or sale... which could invalidate the Jonkers patent.

There have been mods over the years to increase airflow INTO the cockpit, but part of the issue is getting it back out efficiently without a performance hit.
Pressurized air will find a way out, sometimes through the wing by the control hingeline, also not good.
So some air is forced down the tail boom to the base of the rudder, turbulent flow and blanking part of the rudder.
The "turtledeck" is lower pressure and adding air can smooth fuselage airflow.
Also, the lower pressure can help draw out cockpit air, making the vents work better.

Flying high may not need this as much due to lower ambient air temp, flying lower, ambient can be much higher and sitting under a greenhouse.

I can attest to flying with some flavor turtledeck vent as greatly aiding cockpit airflow and possibly helping fill in fuselage turbulent airflow.
You may also have to do some mods to allow air from the cockpit to under the turtledeck (holes in the package shelf for example) to aid this mod.

Alan from LJPanels sends a template for adding three holes to the shelf/bulkhead and includes three round vents to install in order to prevent anything from falling through the holes onto the control linkages.

Paul A.