On Tuesday, December 1, 2015 at 8:23:41 AM UTC-8, Jonathan St. Cloud wrote:
Thank you much and very interesting. Just kind of shows anything can be improved, even yarn taped to a canopy! Perhaps you could do the same with the Quiet vent, how does that work. Just for full disclosure I did buy a Mark IV and a quiet vent, but have yet to install them and have never seen either in practice.


Okay, briefly:

Soaring, should be serene and peaceful, at least when not doing a low save. When flying in the high desert, the experienced pilot should remain cool under the collar. And that Mecaplex flip-out vent sure was noisy, making a particularly bothersome low frequency noise.

The problem is caused by the air hitting the flip out vent, the back edge of the opening, the hinge block and the inside handle when the vent is open. All of the creates turbulence which impedes airflow and makes noise - in a glider that's supposed to be quiet.

The fix is the QV kit. It's made of clear plastic and when installed you won't notice it visually unless you look closely. The QV attaches to the inside handle of the flip-out vent and seals against and near the vent's leading edge to give the incoming air a smooth, rounded transition all the way into the ship. The flow is smoothed, less turbulent, and more air can enter more quietly.

To test in my ASH26E, I installed a QV, then at 60 knots measured the sound level at my ear level. Then, maintaining same speed, wasted a perfectly good QV by ripping it off and repeating sound level measurement. The reduction in noise was 10 dba! Each 3 dba represents a halving of sound pressure level, so dba is a quite significant reduction AND that irksome low frequency component of the noise was all but gone.

The QV was a winner! But, there were initial problems. The material I used at first was too thin, and any alignment error would have the QV acting like the reed on an oboe. This turned out to be quite unpopular, with some pilot ripping the damn thing out. Some others would go high in wave where even a gentle bumping of the QV would have it detach due to the extreme cold - - they were unhappy with me too.

Both issues were fixed of course, and there must be a thousand QVs are out there making soaring more enjoyable, or at least quieter when slowed up, hot, and trying to do a low save.

Price is $9 USD, and as with all the stuff I foist upon the soaring community, satisfaction is guaranteed.

The QV fits Mecaplex flip out vent. A version is available for the Antares on request.


I truly appreciate all the previous positive comments. Thank you everyone!