On Sep 5, 10:03*am, Tim Taylor wrote:
On Sep 4, 7:53*pm, "
wrote:



After all the threads on venting high pressure air overboard I thought
I would share this one with you.

I sealed up the ASW17 canopy and its nice and quiet now.
On Tow yesterday as I retracted the gear the pressure change was
enough to blow the hatch off the top of the turtle deck. *I couldn't
figure out what the noise was at first thinking it was a gear door
who's bungy had broken or come unhooked.

I cycled the gear 2 - 3 times more so thinking it might be an animal
or rock or stuck in the gear well.
The noise continued until I performed a sharp pull up from 80 knots.

The rest of the flight was uneventful except there was more air noise
I attributed to a stuck gear door.
The glider had a slight resonance vibration again I attributed it to
the gear door.

Upon landing I was amazed to see the rigging hatch wedged in the
aperture retained by its lanyard and the remaining tape. It was
aligned 45deg. to the airflow which explained the vibration I was
feeling.

So now the fun part....
The ASW17 has a hatch that is exactly dead center of the fuz. so I am
now working on a replacement air exhaust hatch that will replace the
stock "non breathing" hatch. *I am looking at a design like the ramp
style that Dick butler has on his ASW22.

More to follow.....

Al

Al,

I think a reverse NACA duct is a better model to use. *It will smooth
the transition more and accelerate the air to about equal to the speed
of the outside air for less drag. *I would build one similar to the
one in the link but with a cover over about the first half with a
smooth transition toward the back.

http://www.appletreeauto.com/naca-du...4-pr-3425.html

Tim

But NACA ducts are usually used for inbound air not outbound...

There was another type I saw on a buddies ASH26 but can remember the
name of it began with an E.

Cheers

Al