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Date: Wed, 31 Jul 2013 07:29:35 -0400
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Subject: Re: [LML] Re: Potential Problem-Engine Vibration
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From: Kyrilian Dyer <kyrilian_av@yahoo.com>
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Charley,
I'd be happy to review. Just email me the csv files and I'll see what I can m=
ake of them.
- Kyrilian

Sent from my iPhone

On Jul 30, 2013, at 6:05 AM, Charles Brown <browncc1@verizon.net> wrote:

> Good info Paul.  I am a little chagrined to find that, after loading "Vibr=
ation" on my iPhone and going out to collect data, things were a bunch smoot=
her than I recalled.  The only thing I changed was new spark plugs.  But I t=
hink it's clear that the vibration in my Legacy/IO550 is much less than what=
 I hear Bob and Steve describe.
>=20
> Kyrilian, would you care to examine vibration data from a test ride?  I ha=
ve about 8 files of 15sec X 100Hz data taken with the iPhone secured to the i=
nstrument panel and I don't know what to make of it.
>=20
> Charley
>=20
>=20
> On Jul 29, 2013, at 10:23 AM, Paul Miller wrote:
>=20
> One thing to keep in mind is that the prop balancing on the ground is not a=
s accurate as when the scimitar is loaded in flight. This comes directly fro=
m one of the SX300 guys testing one of the Scimitars for Hartzell on his Lyc=
 580.   What he did was run the cables through the heat duct and perform the=
 balance in flight conditions.  He reported that balancing the scimitars was=
 not easy.  I had a hard time finding a good balance on the ground on the Le=
gacy but it was passable.  I may try the in-flight balance next time at the 2=
300 rpm mark.  Our Legacy scimitars are simply cut shorter than the longer b=
laded scimitars for ground clearance.
>=20
> Second, the engine and cowl moves a lot and the clearances are very tight i=
n the Legacy.  At 2700 RPM and low airspeed the cowl is different shape than=
 at cruise and the engine is in a different position relative to the mounts t=
hat at 2300.  The torque on the engine mounts is much different at 2300 vers=
us 2700.  I found a lot of interference showed up as the RPM came down from 2=
700 to 2300 and then the engine and cowling were slightly separated so that t=
he banging was transmitted.  I believe at other settings the engine was up a=
gainst parts of the cowl and the actual vibration was transmitted.  I had th=
e nose gear interference as well plus the baffling hit the prop governor cab=
le in cruise.  Lots of areas where interference fits are really tight.  My p=
oint is that there are many factors that can affect vibration with changing t=
hrottle and RPM and it isn't just the prop/crankshaft combo that can be at i=
ssue.  I was seeing almost two inches of cowl movement between rest and flig=
ht at certain locations.   Thats a lot.
>=20
> Not to take anything away from the issue under discussion except to say th=
at, in my Legacy, vibration amplitude did change with varying RPM as a resul=
t of mechanical interference.
>=20
> Paul
> Legacy
>=20
>=20

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<html><head><meta http-equiv=3D"content-type" content=3D"text/html; charset=3D=
utf-8"></head><body dir=3D"auto"><div>Charley,</div><div>I'd be happy to rev=
iew. Just email me the csv files and I'll see what I can make of them.</div>=
<div>- Kyrilian<br><br>Sent from my iPhone</div><div><br>On Jul 30, 2013, at=
 6:05 AM, Charles Brown &lt;<a href=3D"mailto:browncc1@verizon.net">browncc1=
@verizon.net</a>&gt; wrote:<br><br></div><blockquote type=3D"cite"><div><div=
>Good info Paul. &nbsp;I am a little chagrined to find that, after loading "=
Vibration" on my iPhone and going out to collect data, things were a bunch s=
moother than I recalled. &nbsp;The only thing I changed was new spark plugs.=
 &nbsp;But I think it's clear that the vibration in my Legacy/IO550 is much l=
ess than what I hear Bob and Steve describe.</div><div><br></div><div>Kyrili=
an, would you care to examine vibration data from a test ride? &nbsp;I have a=
bout 8 files of 15sec X 100Hz data taken with the iPhone secured to the inst=
rument panel and I don't know what to make of it.</div><div><br></div><div>C=
harley</div><div><br></div><br><div><div>On Jul 29, 2013, at 10:23 AM, Paul M=
iller wrote:</div><br class=3D"Apple-interchange-newline"><meta http-equiv=3D=
"Content-Type" content=3D"text/html charset=3Dbig5"><div style=3D"word-wrap:=
 break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space=
; ">One thing to keep in mind is that the prop balancing on the ground is no=
t as accurate as when the scimitar is loaded in flight. This comes directly f=
rom one of the SX300 guys testing one of the Scimitars for Hartzell on his L=
yc 580. &nbsp; What he did was run the cables through the heat duct and perf=
orm the balance in flight conditions. &nbsp;He reported that balancing the s=
cimitars was not easy. &nbsp;I had a hard time finding a good balance on the=
 ground on the Legacy but it was passable. &nbsp;I may try the in-flight bal=
ance next time at the 2300 rpm mark. &nbsp;Our Legacy scimitars are simply c=
ut shorter than the longer bladed scimitars for ground clearance.<div><br></=
div><div>Second, the engine and cowl moves a lot and the clearances are very=
 tight in the Legacy. &nbsp;At 2700 RPM and low airspeed the cowl is differe=
nt shape than at cruise and the engine is in a different position relative t=
o the mounts that at 2300. &nbsp;The torque on the engine mounts is much dif=
ferent at 2300 versus 2700. &nbsp;I found a lot of interference showed up as=
 the RPM came down from 2700 to 2300 and then the engine and cowling were sl=
ightly separated so that the banging was transmitted. &nbsp;I believe at oth=
er settings the engine was up against parts of the cowl and the actual vibra=
tion was transmitted. &nbsp;I had the nose gear interference as well plus th=
e baffling hit the prop governor cable in cruise. &nbsp;Lots of areas where i=
nterference fits are really tight. &nbsp;My point is that there are many fac=
tors that can affect vibration with changing throttle and RPM and it isn't j=
ust the prop/crankshaft combo that can be at issue. &nbsp;I was seeing almos=
t two inches of cowl movement between rest and flight at certain locations. &=
nbsp; Thats a lot.</div><div><br></div><div>Not to take anything away from t=
he issue under discussion except to say that, in my Legacy, vibration amplit=
ude did change with varying RPM as a result of mechanical interference.</div=
><div><br></div><div>Paul</div><div>Legacy</div><div><br></div><style></styl=
e></div></div><br></div></blockquote></body></html>=

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