air extractor for asw19 and asw20

[swanso...@yahoo.com]

I just installed a very cool - pun intended - air extractor in my ASW19. Its a nifty device that replaces that little hatch cover where the control connections are. My guess is that it was made on a 3D printer. Anyway, I couldn’t believe how well it worked and so I’m putting a shameless plug for that thing here. I got it from an outfit in the UK called LJ Panels. I don’t often get carried away raving things, but this one is the cats meow.

[JS]

On Monday, October 16, 2017 at 6:47:55 PM UTC-7, swanso...@yahoo.com wrote:
> I just installed a very cool - pun intended - air extractor in my ASW19. Its a nifty device that replaces that little hatch cover where the control connections are. My guess is that it was made on a 3D printer. Anyway, I couldn’t believe how well it worked and so I’m putting a shameless plug for that thing here. I got it from an outfit in the UK called LJ Panels. I don’t often get carried away raving things, but this one is the cats meow.

Is it anything like the ones that Paul Hanson sold years ago?
Jim

[Paul Agnew]

I just bought the same extractor for my ASW-19 and am waiting to install it. Mine will require a small modification to the block of wood under the opening so the front edge lip will slide in.

Did you cut the vent holes in the aft bulkhead?

Paul A.

[Paul Agnew]

http://ljpanels.co.uk/test/index.php/products/14-extractor-ducts/29-air-extraction-ducts

FYI

[Dan Marotta]

Pretty nifty looking bit of kit!  But I'd think you'd have to make a
cover to close off the ring bulkhead aft of the vent.

On 10/16/2017 10:46 PM, Paul Agnew wrote:
> http://ljpanels.co.uk/test/index.php/products/14-extractor-ducts/29-air-extraction-ducts
>
> FYI

--
Dan, 5J

[Ramy]

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

[Paul Agnew]

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.

[Charlie M. (UH & 002 owner/pilot)]

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.

[Paul Agnew]

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.

[swanso...@yahoo.com]

Some of the ASW19s (and maybe the 20’s) have a fold down wood bulkhead. There is a 1/2 gap around the perimeter that lets the air escape into the fuselage where the air extractor is located. For gliders with a fiberglass bulkhead, the kit includes a template to cut some holes, and also some round plastic screens that prevent the anything other than air from getting through.

As far as glider performance goes, the difference is probably insignificant. But when it comes to pilot comfort, the airflow through the cockpit was probably double what I had before, maybe more.

[swanso...@yahoo.com]

I didn’t cut the holes, but mine has a fold down wood bulkhead with a pretty gap (about 1/2 inch) around the perimeter. That gap was large enough that I though I’d give it a try before cutting the holes. I was happy with the result, so I’ll probaby not cut the holes. The fiberglass bulkhead has a tighter fit, so you may ne d the holes.

John

[sisu1a]

They are similar, but they adopted the dual 'louver' type outlet the Jonkers team came up with. No form on treatment on the interior. Te parts are laser sintered nylon so finish is quite rough (something between sandstone and wood) until primed/sanded, though some Polyprimer and sanding would make them really nice.

My guess is they work at least as well if not better due to having higher surface area with the double outlet even with the forward louver is partly blocked by the attach point, though likely to make a bit more noise with the air hitting the outlet without any organization taking place on the inside.

Wish I would have made my test pod to quantify this stuff, but never did though I do still make/sell the hatches I have been in fiberglass, prefinished with PCL 907 white to a #320 grit

[Dan Mockler]

At 02:17 18 October 2017, sisu1a wrote:
>On Monday, October 16, 2017 at 8:03:30 PM UTC-7, JS wrote:
>> On Monday, October 16, 2017 at 6:47:55 PM UTC-7, swanso...@yahoo.com

>wrot=

>e:
>> > I just installed a very cool - pun intended - air extractor in my

>ASW19=
>.. Its a nifty device that replaces that little hatch cover where the
>contr=

>ol connections are. My guess is that it was made on a 3D printer.

>Anywa=
>y, I couldn=E2=80=99t believe how well it worked and so I=E2=80=99m
>putting=

> a shameless plug for that thing here. I got it from an outfit in the
UK

>=
>called LJ Panels. I don=E2=80=99t often get carried away raving things,
>b=

>ut this one is the cats meow.

>>=20

>> Is it anything like the ones that Paul Hanson sold years ago?
>> Jim
>
>They are similar, but they adopted the dual 'louver' type outlet the

>Jonker=

>s team came up with. No form on treatment on the interior. Te parts are

>las=

>er sintered nylon so finish is quite rough (something between sandstone

>and=

> wood) until primed/sanded, though some Polyprimer and sanding would
make

>t=

>hem really nice.
>
>My guess is they work at least as well if not better due to having higher

>s=

>urface area with the double outlet even with the forward louver is partly

>b=

>locked by the attach point, though likely to make a bit more noise with

>the=

> air hitting the outlet without any organization taking place on the

>inside=
>..=20

>
>Wish I would have made my test pod to quantify this stuff, but never did

>th=

>ough I do still make/sell the hatches I have been in fiberglass,

>prefinishe=

>d with PCL 907 white to a #320 grit
>

After installing a Nixon special in my 20, I heard a burbling sound coming
from
the vent.
I reduced the size of the extractor opening using mylar.
Each flight I would trim another 1/8 inch until the airflow, in the
cockpit,
returned to original levels. Very nice setup.....
I now hear air leaking around the flap while in negative settings.

What sounds are heard due to this design?

[uncl...@ix.netcom.com]

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

[Papa3]

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....

[uncl...@ix.netcom.com]

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

[krasw]

On Friday, 20 October 2017 17:21:04 UTC+3, uncl...@ix.netcom.com 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.

[jpg...@gmail.com]

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.

[Michael Opitz]

>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

[Darryl Ramm]

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

[krasw]

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?

[chip.b...@gmail.com]

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

[JS]

The exit vent in Dick Brandt's Nimbus 3 is at the bottom of the rudder like that. Moved a lot of air.
It was a nice mod to have in Australia.
Jim

[Steve Leonard]

On Tuesday, October 24, 2017 at 11:53:14 AM UTC-5, chip.b...@gmail.com wrote:

>
> 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.
>

> Chip Bearden

A subsequent owner used Nerf balls to plug the air vents when not needed. A red one on the left, and a green one on the right. Got a heck of a scare one day when on a fast final glide, they both blew out into the cockpit at the same time!

Steve Leonard