ASG-29 Coke Bottle Whistle

Originally Posted by Tom Kelley #711

On Sunday, June 12, 2016 at 12:43:14 PM UTC-6, RickH wrote:
I hope some of you ASG-29 drivers have either experienced or heard of
this issue I'm having with my 2012 ASG-29. The ship has about 200 hours
on it. At about 100-110 knots I have a very loud and annoying sound
that comes from the rear of the ship. It sounds just like someone
blowing over a coke bottle to create a tone. I can get rid of the sound
by applying a little rudder although the yaw string is running true
while the sound is being generated. Rex Williams said he thought it was
the tail dump opening. I've put duct tape over the tail dump valve and
still have this annoying tone accelerating through 100-110 knots. John
Murray thought that it was the gap seal tape on the rudder. I would
have thought that would have produced more of a buzz sound but this is
probably my next step. Hopefully someone can enlighten me as to a
possible cause!




--
RickH

When my 29 was new in 2006, I had maybe the same noise around 95-100 kts. When I got home from the Nationals, I removed the rudder and really bent the mylar over. Used a small wood block and even creased it at almost a 90 degree angle. Reinstalled the rudder and the noise went away.
Then several years ago, installed new mylar. Didn't crease it over. Flew it and the noise came back. Came home, removed the rudder and bent it over using again a small block of wood to crease it and the nose went away. Several other folks with the same noise simply trimmed the mylar down from the top by an inch or so. The bottom they trimmed up. Their noise went away.

Best. Tom #711.

Thanks Tom, that sounds promising as well as some of the other tips regarding sealing around the rudder cable faring. I do have the MN exhaust and I glassed up the edges of the cockpit exhaust collector so it seals tightly. Wing gap seal tape is good all around as well, so directing my attention to the tail is probably the best bet. I had a 27B before my 29 and it had the MN cockpit exhaust as well. It was quiet all the way up to as fast as I dared take it! Thanks again for the comments, at least I don't feel that I have a one-off now-

Rick
NR