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my 9A whistles in flight

carguy614

carguy614

Well Known Member
Hi All...
While watching my buddy Jan fly my plane the other day, I could not help but notice a distinct whistle. Kinda sounds like a jet flying over. Cruise flight only. O-320 with Sensenich fixed pitch prop. I cannot hear it inside the cockpit at any time. I have heard other planes make similar noise, but wondered if any of you can shed some light. I suspect prop is the culprit.
Thanks...Chris
 
Yup, seems like a lot of them do it. Mine does. Someone recently said it is the elevator hinge gaps.

Bob Kelly
 
Hi Chris,

My 9a also whistles in flight. It is most noticeable on mine while in the pattern. I can not hear it from inside the cabin but several on the ground have commented on it. Some friends in Lockhart (Ted and Phil) were curious as to the source of the whistle on Ted's 9a and did some testing. They determined that when you tape off the elevator hinge openings the whistle goes away. There is some info in the archives on this.

Cheers,

db
 
Tipup or slider?

My tipup had a whistle until I put a form-in-place seal on the aft edge where it meets the frame.
 
9/9A whistles regardless tipup or slider. The source is confirmed (by a few people) to be elevator hinge openings.
 
Did I build my wrong?

I can't hear mine whistle and no one has ever mentioned the sound after I land.

Kent
 
Whistle While You Work

Nothing better than having a happy partner (our RV's) that is happy, content, and whistles while they work. :)
 
Turbo 9

There are 3 flying 9's here at Cable Airport, Upland,CA. All have the cool 'turbo' sound when arriving in the pattern. I agree, it's the elevator hinge openings that are causing the sound.
 
Speed Tape

My mate Pete Pendergast asked me to fly with him in his RV7 to see if I could locate the origins of a 'Buzz' (as he described it) in his aircraft.
Passing 130kt the noise began, but it was a high pitch whistle, rather than a buzz.
I immediately identified it as the same noise I had occasionally heard from poorly sealed doors on airliners I had flown over the years. The occurrence was rare, but when it occurred life in the galley for the girls was **** due to the very high frequency of the whistle.
The engineers fixed it with 'Speed Tape'. That is adhesive aluminium tape.
The noise in Pete's machine was coming from the join in his tipper canopy. So we landed and I climbed out and sealed him in by running duct tape over the join at the aft end of his tipper canopy, to stop the flow through the gap between the canopy and the roll bar. I suspect that the smaller the gap between the canopy and the roll bar the higher the frequency of the noise. Pete's gap was not visible. He builds good RVs.
Pete took off for a test flight and returned shortly after saying the noise had disappeared completely; after I had unsealed him and let him out.
The final fix was some very thin foam strip door sealer placed under the aft lip of the canopy where it sits on the frame.

Pete.
 
whistler

Seems like the whistle is a 9 thing. Actually, I really like it, and have already received comment....."Heard you fly over yesterday". Thanks for the input and grins.....

Chris
 
carguy614 said:
Seems like the whistle is a 9 thing. Actually, I really like it, and have already received comment....."Heard you fly over yesterday". Thanks for the input and grins.....
Click to expand...

I live under an airport pattern, and kind of like whisteling planes too....

However, after about 60 hours between two 9A's with sliding canopies, I've never heard a whistle within. But I also have noise-cancelling headphones.

L.Adamson
 
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