ASG-29 Coke Bottle Whistle

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!

Let me know how you solve it. My LS-8 has the exact same noise at the same speed. Slight rudder pressure makes it go away. Rudder gap seals are tight.

At 14:37 12 June 2016, RickH wrote:

I hope some of you ASG-29 drivers have either experienced or
heard o
this issue I'm having with my 2012 ASG-29. The ship has about
200 hour
on it. At about 100-110 knots I have a very loud and annoying
soun
that comes from the rear of the ship. It sounds just like someon
blowing over a coke bottle to create a tone. I can get rid of the
soun
by applying a little rudder although the yaw string is running tru
while the sound is being generated. Rex Williams said he thought it
wa
the tail dump opening. I've put duct tape over the tail dump valve
an
still have this annoying tone accelerating through 100-110 knots.
Joh
Murray thought that it was the gap seal tape on the rudder. I woul
have thought that would have produced more of a buzz sound but
this i
probably my next step. Hopefully someone can enlighten me as to
possible cause




--
RickH
We had a similar issue with an LS4a. It turned out to be the root
wing seal tape on the lower surface. If the tape was not sealed
tightly to the lower surface, we would get the tone. The noise
sounded like it was coming from the aft end of the ship, but pressing
the tape tight to the lower surface of the wing would stop the
problem.

Jim

On Sunday, June 12, 2016 at 2:43:14 PM UTC-4, 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

Guessing it is turbulence over the rudder cable outlet which is not followed by a trailing faring. Fashion a faring out of DOW blue styrofoam square edge insulation (Lowes). First put down a strip of duck tape and then glue the shaped foam trailing faring to the duct tape. Do for both sides and flight test. If this eliminates the whistle then proceed to fabricate and permanently install FG shell faring.

RickH,

How much equipment do you stow behind your head?

On my LS4 if there was too much equipment (sweatshirt, jacket etc) on the
cargo shelf it caused a 'choke' and the fuselage exhaust at the base of the
fin
would start to howl.

Trial an error sorted it out, but also worth making sure the internal
rudder
seal (if fitted) is fully adhered to the fin and making contact with the
rudder.

GG

At 14:37 12 June 2016, RickH wrote:

I hope some of you ASG-29 drivers have either experienced or heard o
this issue I'm having with my 2012 ASG-29. The ship has about 200 hour
on it. At about 100-110 knots I have a very loud and annoying soun
that comes from the rear of the ship. It sounds just like someon
blowing over a coke bottle to create a tone. I can get rid of the soun
by applying a little rudder although the yaw string is running tru
while the sound is being generated. Rex Williams said he thought it wa
the tail dump opening. I've put duct tape over the tail dump valve an
still have this annoying tone accelerating through 100-110 knots. Joh
Murray thought that it was the gap seal tape on the rudder. I woul
have thought that would have produced more of a buzz sound but this i
probably my next step. Hopefully someone can enlighten me as to
possible cause




--
RickH

Hi Rick,

I have the same 100 kt whistle on my 29. Just today replaced the upper mylar on the elevator in an attempt to remove the noise. I'll see if it goes away and report back. I also have new mylar for the lower surface and that is the next test if replacing the upper doesn't solve it. Let me know if you replace rudder seals and if that solves the problem on yours.

Dave Springford

The high speed noise is very common in the ASG29. The ASW 27 will also make the noise but needs to be at high altitude and high speed (like 17k at 105+knots.)

So sadly, I don't know of anyone who has cured this yet but maybe broadening the question to include ASW 27 pilots who fly regularly at high altitude will yield an answer.

In my own plane I've tried to seal air from getting into or out of the vertical fin via around the elevator and rudder joints. Not cured yet but I'll be at the Utah nationals next week so I'll be able to test out a couple of ideas.

On Sunday, June 12, 2016 at 11:43:14 AM UTC-7, 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

As John Murry said.
My Discus 2b had the same issue after the rudder seals blew out in an overnight wind storm. I put them back in, but it still buzzed.
Craig

On Sunday, June 12, 2016 at 2:43:14 PM UTC-4, 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

Some things I have done with some success.
Install a bulkhead in the fin cove with a wiping seal against the leading edge of the rudder to stop flow up the fin cove area.
Seal the elevator push rod exit.
Add wipe seals to the sides of the elevator drive
Install ES vent so cockpit air exits forward instead of at the tail.
FWIW
UH

On a club LS4 as well as an LS4 I used to own, we had the same problem. Sounds like a bassoon player sitting in the area of the empennage. Turned out that sealing the top of the vertical stab with foam around the elevator pushrod solved the problem. My 29 hasn't yet displayed this musical tendency, but I have a Nixon/Murray exhaust vent which provides an optimized path for high pressure cockpit air to escape...

P3