X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Fri, 26 Jul 2013 16:30:38 -0400 Message-ID: X-Original-Return-Path: Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122] verified) by logan.com (CommuniGate Pro SMTP 6.0.5) with ESMTP id 6392524 for lml@lancaironline.net; Fri, 26 Jul 2013 15:20:37 -0400 Received-SPF: none receiver=logan.com; client-ip=71.74.56.122; envelope-from=Wolfgang@MiCom.net X-Original-Return-Path: X-Authority-Analysis: v=2.0 cv=e9yEuNV/ c=1 sm=0 a=MHZY6FYWMEQOp7S43i2QIw==:17 a=3Zlka_XeuxsA:10 a=uoFbTxqA3N0A:10 a=ttCsPuSJ-FAA:10 a=rTjvlri0AAAA:8 a=KGjhK52YXX0A:10 a=I1SdC7XVI-cA:10 a=Ia-xEzejAAAA:8 a=mCSqThwqAAAA:8 a=CjxXgO3LAAAA:8 a=GDvJEaaRAAAA:8 a=gP-Iyt7oAAAA:8 a=xHHRXPc-rGvvgrmBUFEA:9 a=wPNLvfGTeEIA:10 a=rnYgdqcAs4AA:10 a=-ZBvsNeBbbMA:10 a=EzXvWhQp4_cA:10 a=rC2wZJ5BpNYA:10 a=nYNn1GbNWs8A:10 a=CgRqhVk1oUYHbq2LlZQA:9 a=_W_S_7VecoQA:10 a=RGzsX6QO0QU9KQpF:21 a=MHZY6FYWMEQOp7S43i2QIw==:117 X-Cloudmark-Score: 0 X-Authenticated-User: X-Originating-IP: 74.218.201.50 Received: from [74.218.201.50] ([74.218.201.50:3228] helo=lobo) by hrndva-oedge01.mail.rr.com (envelope-from ) (ecelerity 2.2.3.46 r()) with ESMTP id D5/1A-18705-2EBC2F15; Fri, 26 Jul 2013 19:20:02 +0000 X-Original-Message-ID: <80C5CC7523F84132BA3A70B13CCEC328@lobo> From: "Wolfgang" X-Original-To: References: Subject: Re: [LML] Re: Potential Problem-Engine Vibration X-Original-Date: Fri, 26 Jul 2013 15:20:04 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_003D_01CE8A13.9A86F2B0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5512 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5512 This is a multi-part message in MIME format. ------=_NextPart_000_003D_01CE8A13.9A86F2B0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable It sounds like accelerometers mounted in suspect locations with the = engine running at the RPM indicated by the spike shown by the Apple app. = would lead you to the culprit. Wolfgang ----- Original Message -----=20 From: John Smith=20 To: lml@lancaironline.net=20 Sent: Friday, July 26, 2013 12:47 PM Subject: Re: [LML] Re: Potential Problem-Engine Vibration Kryilian, I too have this vibration phenomenon in VH-XTZ - I spent hours and = hours of flying time trying to isolate it, trying different power = settings, different aircraft loading, different angles of attack, you = name it - I could not find a pattern. Mostly its there, but occasionally = nothing. Visually, it manifests itself with a very slight port wing tip = / aileron quiver; physically, you can mainly feel it ever so slightly in = the rudder pedals. Having said all this, others fly in the aircraft and = don't know what I'm on about. But, I have now found that running at = about 2540rpm is quite smooth and all but gets rid of the vibration. Its = noticeably worse at say 2400 - 2450rpm. So - endeavouring to quantify things, I employed the iPhone App you = have mentioned. The attached pics are from way back in 2011; these = should give everyone an idea of what can be produced. Below my comments = at the time wrt to attached samples. As one of our other forum contributors mentioned, vibration is very = subjective without the use of measurement devices. so can I suggest that = those whip have access to iPhones go flying and capture outputs in the = same manner and with same engine settings - how about with iPhone = resting on centre console and engine set at 2500rpm, 19" and leaned = 28degC (50degF) rich of peak.. Or as anyone else might suggest = otherwise. Then we can all collect data that should be legitimately = comparable, and perhaps identify if there are any substantial = differences in the vibration characteristics. Anyways, just an idea.. Comments from tests in August 2011:- Captured three outputs with 2400rpm and about 19" MAP. First sample = with iPhone on the centre console shows a spike at ~20Hz - that is = approx. equivalent to 1200rpm, which exactly half the engine engine rpm. = For other two samples, iPhone on the dust cover in the middle and then a = bit to one side; these show the same 20Hz spike, and also a spike around = 38 - 40Hz - this would seem to be close to the engine rpm, but 38Hz is = equivalent to 2280rpm, which does not make sense as there is no way the = engine rpm varies by that much. So, I'm not sure what all this means. = I'd love to get the iPhone onto the rudder pedals, but that's kind of = tricky! The iPhone doesn't measure above 50Hz, so I can detect prop beat = or exhaust beat. Regards, John John N G Smith Tel / fax: +61-8-9385-8891 Mobile: +61-409-372-975 Email: john@jjts.net.au From: Kyrilian Dyer Reply-To: Lancair Mailing List Date: Friday, 26 July 2013 6:22 PM To: Subject: [LML] Re: Potential Problem-Engine Vibration If you'd like to measure the frequency and amplitude of relatively = low frequency vibration I'd recommend an iPhone app called 'Vibration' = ($4.99 from the App Store). It's certainly not high end but it may help = in characterizing some of the vibrations that you guys describe. The = only problem I see is that it only samples up to 100 Hz, which gives you = frequency data up to 44.9 Hz (~2690 rpm). This won't give you any data = at propeller frequencies. But it may help tell if its a function of RPM = at 1/rev, or if it's asynchronous with the engine (and doesn't correlate = with engine speed, such as buffet or flutter). A few screenshots (recording of an out of balance car tire at 70 = mph) are shown below. Note that the app can output data to a .csv file, = which can be reviewed/analyzed later. I do this sort of thing with = proper accelerometers, recorders and analyzers on helicopters in my day = job, so I'd like to help if I can. If anyone has luck with the iPhone = app please send me the data files. Perhaps we could then compare = between aircraft. Regards, - Kyrilian L2K-236 Time display: DFT (note spike at around 16 Hz) Setup (one of several sub screens) Sent from my iPhone On Jul 25, 2013, at 8:46 PM, "Dennis Johnson" = wrote: I have a smooth running Legacy RG IO-550 with a three blade = Hartzell scimitar prop, HC-J3YF-1RF/F7391D-3/SM7. =20 According to Hartzell's website, this is the recommended three = blade scimitar prop for the Legacy RG with IO-550 engine. It is a 72" = diameter prop, not the 78" prop mentioned in Bob R's posting. I thought = all the scimitar props on Legacys were the same as mine. = http://hartzellprop.com/pilots/kit-builders/legacy-2000-io-550-n-3-blade/= I consider mine to be "smooth," but that is a terribly subjective = concept. However, I can say for sure that I do not feel vibration in = the stick and don't see any aileron vibration or wing tip vibration. = Another Legacy builder and pilot commented on how smooth mine is, but = maybe he was just being polite. =20 Unless there is a way to quantify "vibration" and "smoothness," I = don't see how we can accurately communicate about this. One person's = rough could be another person's smooth. Maybe if someone had a video of = stick shake or aileron shake? A glass of water sitting on the glare = shield?=20 Dennis Legacy 625 hours =20 =20 -------------------------------------------------------------------------= ----- -------------------------------------------------------------------------= ----- -------------------------------------------------------------------------= ----- ------=_NextPart_000_003D_01CE8A13.9A86F2B0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
It sounds like accelerometers mounted = in suspect=20 locations with the engine running at the RPM indicated by the spike = shown by the=20 Apple app. would lead you to the culprit.
 
Wolfgang
 
----- Original Message -----
From:=20 John = Smith
Sent: Friday, July 26, 2013 = 12:47=20 PM
Subject: Re: [LML] Re: = Potential=20 Problem-Engine Vibration

Kryilian,

I too have this vibration phenomenon in VH-XTZ =96 I spent hours = and hours=20 of flying time trying to isolate it, trying different power settings,=20 different aircraft loading, different angles of attack, you name it = =96 I could=20 not find a pattern. Mostly its there, but occasionally nothing. = Visually, it=20 manifests itself with a very slight port wing tip / aileron quiver;=20 physically, you can mainly feel it ever so slightly in the rudder = pedals.=20 Having said all this, others fly in the aircraft and don't know what = I'm on=20 about.  But, I have now found that running at about 2540rpm is = quite=20 smooth and all but gets rid of the vibration. Its noticeably worse at = say 2400=20 =96 2450rpm.

So =96 endeavouring to quantify things, I employed the iPhone App = you have=20 mentioned.  The attached pics are from way back in 2011; these = should=20 give everyone an idea of what can be produced. Below my comments at = the time=20 wrt to attached samples.

As one of our other forum contributors mentioned, vibration is = very=20 subjective without the use of measurement devices=85 so can I suggest = that those=20 whip have access to iPhones go flying and capture outputs in the same = manner=20 and with same engine settings =96 how about with iPhone resting on = centre=20 console and engine set at 2500rpm, 19" and leaned 28degC (50degF) rich = of=20 peak=85. Or as anyone else might suggest otherwise.  Then we can = all=20 collect data that should be legitimately comparable, and perhaps = identify if=20 there are any substantial differences in the vibration = characteristics.=20 Anyways, just an idea=85.

Comments from tests in August = 2011:-

Captured=20 three outputs with 2400rpm and about 19=94 MAP.  First sample = with iPhone=20 on the centre console shows a spike at ~20Hz =96 that is approx. = equivalent to=20 1200rpm, which exactly half the engine engine rpm. For other two = samples,=20 iPhone on the dust cover in the middle and then a bit to one side; = these show=20 the same 20Hz spike, and also a spike around 38 - 40Hz =96 this would = seem to be=20 close to the engine rpm, but 38Hz is equivalent to 2280rpm, which does = not=20 make sense as there is no way the engine rpm varies by that much. So, = I=92m not=20 sure what all this means. I=92d love to get the iPhone onto the rudder = pedals,=20 but that=92s kind of tricky! The iPhone doesn=92t measure above 50Hz, = so I can=20 detect prop beat or exhaust beat.


Regards,

John


John N G Smith
Tel / fax:=20    +61-8-9385-8891
Mobile:=20      +61-409-372-975
Email:=20 =         john@jjts.net.au

<= /FONT>

From: Kyrilian Dyer <kyrilian_av@yahoo.com>
Reply-To: Lancair Mailing List = <lml@lancaironline.net>
Date: Friday, 26 July 2013 6:22 = PM
To: <lml@lancaironline.net>
Subject: [LML] Re: Potential = Problem-Engine=20 Vibration

If you'd like to measure the frequency and amplitude of = relatively low=20 frequency vibration I'd recommend an iPhone app called 'Vibration' = ($4.99=20 from the App Store).  It's certainly not high end but it may = help in=20 characterizing some of the vibrations that you guys describe. The = only=20 problem I see is that it only samples up to 100 Hz, which gives you=20 frequency data up to 44.9 Hz (~2690 rpm).  This won't give you = any data=20 at propeller frequencies.  But it may help tell if its a = function of=20 RPM at 1/rev, or if it's asynchronous with the engine (and doesn't = correlate=20 with engine speed, such as buffet or flutter).

A few screenshots (recording of an out of balance car tire at = 70 mph)=20 are shown below. Note that the app can output data to a .csv file, = which can=20 be reviewed/analyzed later.  I do this sort of thing with = proper=20 accelerometers, recorders and analyzers on helicopters in my day = job, so I'd=20 like to help if I can.  If anyone has luck with the iPhone app = please=20 send me the data files.  Perhaps we could then compare between=20 aircraft.

 Regards,
- Kyrilian
  L2K-236

Time display:
3Dimage.png=20

DFT (note spike at around 16 Hz)
3Dimage.png=20

Setup (one of several sub screens)
3Dimage.png=20


Sent from my iPhone

On Jul 25, 2013, at 8:46 PM, "Dennis Johnson" <pinetownd@volcano.net>=20 wrote:

I have a smooth running Legacy RG IO-550 with a three blade = Hartzell=20 scimitar prop, HC-J3YF-1RF/F7391D-3/SM7. 
 
According to Hartzell's website, this is the recommended = three blade=20 scimitar prop for the Legacy RG with IO-550 engine.  It is a = 72"=20 diameter prop, not the 78" prop mentioned in Bob R's = posting.  I=20 thought all the scimitar props on Legacys were the same as = mine.
 
http://hartzellprop.com/pilots/kit-builders/legacy-2000-io-550-= n-3-blade/
 
I consider mine to be "smooth," but that is a terribly = subjective=20 concept.  However, I can say for sure that I do not feel = vibration in=20 the stick and don't see any aileron vibration or wing tip=20 vibration.  Another Legacy builder and pilot commented = on how=20 smooth mine is, but maybe he was just being polite.    =
 
Unless there is a way to quantify "vibration" and = "smoothness," I=20 don't see how we can accurately communicate about this.  One = person's=20 rough could be another person's smooth.  Maybe if = someone had a=20 video of stick shake or aileron shake?  A glass of water = sitting on=20 the glare shield? 
 
Dennis
Legacy 625 hours 
 
 
 
 
 
 
=
 

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