Today's Message Index:
----------------------
1. 03:56 PM - (Cye Vaughan)
2. 07:04 PM - Re: (Arvil)
3. 07:22 PM - Strange Vibration (Oldsfolks@aol.com)
4. 10:31 PM - Re: strange one (LessDragProd@aol.com)
Message 1
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--> 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
Message 2
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| Subject: | Re: e: RV4-List: |
--> RV4-List message posted by: Arvil <arvil@bellsouth.net>
Put on another prop and see if it still dose it,---- Fly in another
RV-4 and see if it still dos it might be just an RV-4 sound---- Check
the motor mounts ------ if you are still not sadasfide check the gear
feairing and weel pants for aliment!----- if you are at your wits end by
then and it still has the the sound ---- check your antennas they can
set up a harmonic that will drive you plum nuts-- Good luck'
Arvil
Cye Vaughan wrote:
> --> 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
>
Message 3
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| Subject: | Strange Vibration |
--> RV4-List message posted by: Oldsfolks@aol.com
Someone had quite a discussion going awhile back on a vibration which they
changed by shifting the prop alignment in relation to top dead center of the
pistons. Maybe you could try changing the prop setting one hole at a time to see
if it would go away? Then again your crank lugs may prevent doing that.
It sounds like the prop harmonics though.
Bob Olds -- RV-4 , N1191X
oldsfolks@aol.com
A&P , EAA Tech. Counselor
Charleston,Arkansas
Real Aviators Fly Taildraggers
Message 4
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--> RV4-List message posted by: LessDragProd@aol.com
Hi All,
Van's had a vibration occurring in the same speed range on their RV-8. They
traced to the engine baffle seal material vibrating against the cowl. If I
recall correctly, their seal strip had been push aft, instead of facing forward
towards the engine.
Jim Ayers
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