Today's Message Index:
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1. 06:01 AM - Re: (Pat Perry)
2. 12:15 PM - Re: (rob ray)
Message 1
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--> RV4-List message posted by: "Pat Perry" <pperryrv@hotmail.com>
Check all of your cowl clearances. One little contact point from the
engine, airbox, or baffle will cause a loud noise in the airfram. If the
engine has a slight orbital cycle like a gyroscope gets when it is wandering
off its axis I could imagine it making that kind of noise.
I had a slight contact point with my airbox and cowl that would make a load
noise during any 1.2G or more manuver that drove me nuts until I moved the
box 1/4" to the left.
Pat Perry
Dallas, PA
RV-4 N154PK Flies great!
>From: "Cye Vaughan" <cyenjoy@ctnis.com>
>Reply-To: rv4-list@matronics.com
>To: <rv4-list@matronics.com>
>Subject: RV4-List: Date: Thu, 25 Mar 2004 15:55:49 -0800
>
>--> RV4-List message posted by: "Cye Vaughan" <cyenjoy@ctnis.com>
>
>I have a strange one. My RV-4 with 36 total hours (Van's 180 Lyc, Sensenich
>metal prop) has a very strange harmonic that seems to run through the
>airframe. This happens in level flight, mostly above 140 mph indicated at
>8000' and as speed is increased toward 170 indicated it seems to beat at a
>faster rate. Rpm is between 2300-2500. If you have ever flown a twin with
>the engines slightly out of synch you would recognize the sound. Kind of a
>"wow-wow-wow" sound. I had the prop checked for balance and it was so good
>it didn't need any balancing.
>
>There is no apparent vibration in any of the controls, everything outside
>is tight, canopy locks down tight. This is a good airplane, flies straight,
>and except for this strange sound I couldn't be happier with it.
>
>If anyone has heard of or experienced this problem I would sure like to
>hear about it. By the way, I called Van's and spoke to one of his guys who
>had never heard of this.
>
>Cye Vaughan
>Elko NV
>cyenjoy@ctnis.com
>
>
download! http://toolbar.msn.com/go/onm00200413ave/direct/01/
Message 2
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--> RV4-List message posted by: rob ray <smokyray@yahoo.com>
Pat,
I hate to say it, but my RV4 had the exact same airframe vibrations with a Sensy
metal prop. I tried dynamic balancing, harmonic dampener and many different
power settings and finally sold the prop and put a Catto on. Problem solved.
That's not to say you have the same problem, but I tried a second sensy from a
friend to "break it in" for him and get some performance numbers. Again, the
same problem re-appeared.
When I re-mounted my Catto prop, problem solved.
One thing I would re-check is the mag timing and Electronic Ignition timing if
you have it. It's critical on an 0-360. Also, dynamic balancing is cheap insurance,
that might help too.
For me, prop removal was the fix.
Good Luck.
Rob Ray
Pat Perry <pperryrv@hotmail.com> wrote:
--> RV4-List message posted by: "Pat Perry"
Check all of your cowl clearances. One little contact point from the
engine, airbox, or baffle will cause a loud noise in the airfram. If the
engine has a slight orbital cycle like a gyroscope gets when it is wandering
off its axis I could imagine it making that kind of noise.
I had a slight contact point with my airbox and cowl that would make a load
noise during any 1.2G or more manuver that drove me nuts until I moved the
box 1/4" to the left.
Pat Perry
Dallas, PA
RV-4 N154PK Flies great!
>From: "Cye Vaughan"
>Reply-To: rv4-list@matronics.com
>To:
>Subject: RV4-List: Date: Thu, 25 Mar 2004 15:55:49 -0800
>
>--> RV4-List message posted by: "Cye Vaughan"
>
>I have a strange one. My RV-4 with 36 total hours (Van's 180 Lyc, Sensenich
>metal prop) has a very strange harmonic that seems to run through the
>airframe. This happens in level flight, mostly above 140 mph indicated at
>8000' and as speed is increased toward 170 indicated it seems to beat at a
>faster rate. Rpm is between 2300-2500. If you have ever flown a twin with
>the engines slightly out of synch you would recognize the sound. Kind of a
>"wow-wow-wow" sound. I had the prop checked for balance and it was so good
>it didn't need any balancing.
>
>There is no apparent vibration in any of the controls, everything outside
>is tight, canopy locks down tight. This is a good airplane, flies straight,
>and except for this strange sound I couldn't be happier with it.
>
>If anyone has heard of or experienced this problem I would sure like to
>hear about it. By the way, I called Van's and spoke to one of his guys who
>had never heard of this.
>
>Cye Vaughan
>Elko NV
>cyenjoy@ctnis.com
>
>
download! http://toolbar.msn.com/go/onm00200413ave/direct/01/
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