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#1
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air extractor for asw19 and asw20
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.
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#2
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air extractor for asw19 and asw20
On Monday, October 16, 2017 at 6:47:55 PM UTC-7, 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 |
#3
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air extractor for asw19 and asw20
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. |
#4
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air extractor for asw19 and asw20
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#5
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air extractor for asw19 and asw20
Pretty nifty looking bit of kit!Â* 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...traction-ducts FYI -- Dan, 5J |
#6
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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 |
#7
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air extractor for asw19 and asw20
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. |
#8
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air extractor for asw19 and asw20
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. |
#9
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air extractor for asw19 and asw20
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. |
#10
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air extractor for asw19 and asw20
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. |
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