X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail17.syd.optusnet.com.au ([211.29.132.198] verified) by logan.com (CommuniGate Pro SMTP 5.2c1) with ESMTPS id 2552441 for flyrotary@lancaironline.net; Sun, 02 Dec 2007 18:07:44 -0500 Received-SPF: none receiver=logan.com; client-ip=211.29.132.198; envelope-from=lendich@optusnet.com.au Received: from george (d58-108-72-98.dsl.nsw.optusnet.com.au [58.108.72.98]) by mail17.syd.optusnet.com.au (8.13.1/8.13.1) with SMTP id lB2N5YFA019730 for ; Mon, 3 Dec 2007 10:06:52 +1100 Message-ID: <006301c83538$08c63fb0$62486c3a@george> From: "George Lendich" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Giving up on single rotor Date: Mon, 3 Dec 2007 09:05:05 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_004A_01C8358B.9878D0C0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2180 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 X-Antivirus: avast! (VPS 0657-0, 12/12/2006), Outbound message X-Antivirus-Status: Clean This is a multi-part message in MIME format. ------=_NextPart_000_004A_01C8358B.9878D0C0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MessageAl, It sounds like you might be right - but I wish I had an idea of what = your talking about in regard to torque V angle of deflection. I do my best but you have me beat on this one. George ( down under) ----- Original Message -----=20 From: Al Wick=20 To: Rotary motors in aircraft=20 Sent: Monday, December 03, 2007 1:19 AM Subject: [FlyRotary] Re: Giving up on single rotor Instead of using durometer in this case. I think it would be better to = measure torque vs. angle of deflection. Using torque wrench and simple = angle measure device. If you graphed this, you would end up with a chart = that defines frequency response of the damper. Goal to have damper = frequency response that's out of phase with the worst torsional pulses.=20 Once you've measured frequency response, you could then tune it with = durometer tweaks. So you might end up with 2 dampers at 50 durometer, 2 = at 40, to obtain your ideal frequency response of system. I've always been drawn to having damper that has more than one = frequency response. You never see designs like that. So with mild TV, it = would respond one way. Suddenly it would have different response with = larger TV. Both responses out of phase. They use this method with = electronics and I've seen a few auto clutch dampers utilizing the = concept.=20 FWIW al wick ----- Original Message -----=20 From: George Lendich=20 To: Rotary motors in aircraft=20 Sent: Saturday, December 01, 2007 10:46 PM Subject: [FlyRotary] Re: Giving up on single rotor Righ-t-o Rusty! Thanks George ( down under) So what durometer is your gut feeling now that you went this far?=20 Hi George, I don't think you can compare the durometer of one damper to = another, because the physical size is as important as the hardness of = the rubber. The Autoflight drive uses a stock Centaflex coupler that's = only available in 50 and 60 durometer. It's a fairly large diameter, = and thick coupler. 50 was better than 60, but two 50's (effectively 25) = in series was way too soft. Maybe a 40 would be good, but it doesn't = exist. =20 Richard seems to be having better luck with the Hirth drive. Two = strokes are rough at low rpms, so perhaps they already have the right = damper for the job. I also suspect his engine has softer power pulses = at low rpms. It's a 12A for one, and PP for another. PP is great at = high rpms, but not know for good power down low. It's the best theory I = have. =20 Cheers, Rusty =20 -------------------------------------------------------------------------= - No virus found in this incoming message. Checked by AVG Free Edition.=20 Version: 7.5.503 / Virus Database: 269.16.11/1161 - Release Date: = 30/11/2007 12:12 PM -Al Wick Cozy IV powered by Turbo Subaru 3.0R with variable valve lift and cam = timing.=20 Artificial intelligence in cockpit, N9032U 240+ hours from Portland, = Oregon Glass panel design, Subaru install, Prop construct, Risk assessment = info: http://www.maddyhome.com/canardpages/pages/alwick/index.html -------------------------------------------------------------------------= ----- No virus found in this incoming message. Checked by AVG Free Edition.=20 Version: 7.5.503 / Virus Database: 269.16.11/1161 - Release Date: = 30/11/2007 12:12 PM ------=_NextPart_000_004A_01C8358B.9878D0C0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message
Al,
It sounds like you might be right - but = I wish I=20 had an idea of what your talking about in regard to torque V angle of=20 deflection.
I do my best but you have me beat on = this=20 one.
George ( down under)
----- Original Message -----
From:=20 Al Wick =
Sent: Monday, December 03, 2007 = 1:19=20 AM
Subject: [FlyRotary] Re: Giving = up on=20 single rotor

Instead of using durometer in this = case. I think=20 it would be better to measure torque vs. angle of deflection. Using = torque=20 wrench and simple angle measure device. If you graphed this, you would = end up=20 with a chart that defines frequency response of the damper. Goal to = have=20 damper frequency response that's out of phase with the worst torsional = pulses.=20
 
Once you've measured frequency = response, you=20 could then tune it with durometer tweaks. So you might end up with 2 = dampers=20 at 50 durometer, 2 at 40, to obtain your ideal frequency response of=20 system.
 
I've always been drawn to having = damper that has=20 more than one frequency response. You never see designs like that. So = with=20 mild TV, it would respond one way. Suddenly it would have different = response=20 with larger TV. Both responses out of phase. They use this method with = electronics and I've seen a few auto clutch dampers utilizing the = concept.=20
 
FWIW
 
al wick
----- Original Message -----
From:=20 George Lendich
To: Rotary motors in = aircraft=20
Sent: Saturday, December 01, = 2007 10:46=20 PM
Subject: [FlyRotary] Re: = Giving up on=20 single rotor

Righ-t-o Rusty!
Thanks
George ( down under)
So what durometer is your = gut feeling=20 now that you went this far? 
 
Hi = George,
 
I don't think you can compare the = durometer of one=20 damper to another, because the physical size is as important as = the=20 hardness of the rubber.  The Autoflight drive uses a stock = Centaflex=20 coupler that's only available in 50 and 60 durometer.  It's a = fairly=20 large diameter, and thick coupler.  50 was better than 60, = but two=20 50's (effectively 25) in series was way too soft.  Maybe = a 40=20 would be good, but it doesn't=20 exist.  
 
Richard seems to be having better = luck with=20 the Hirth drive.  Two strokes are rough at low rpms, so = perhaps=20 they already have the right damper for the job.  I also = suspect=20 his engine has softer power pulses at low rpms.  It's a 12A = for one,=20 and PP for another.  PP is great at high rpms, but not know = for good=20 power down low.  It's the best theory I=20 have.  
 
Cheers,
Rusty =  

No virus found in this incoming message.
Checked by AVG = Free=20 Edition.
Version: 7.5.503 / Virus Database: 269.16.11/1161 - = Release=20 Date: 30/11/2007 12:12 PM
-Al Wick
Cozy IV powered by Turbo Subaru 3.0R with variable = valve lift=20 and cam timing.
Artificial intelligence in cockpit, N9032U 240+ = hours from=20 Portland, Oregon
Glass panel design, Subaru install, Prop = construct, Risk=20 assessment info:
htt= p://www.maddyhome.com/canardpages/pages/alwick/index.html

No virus found in this incoming message.
Checked by AVG Free = Edition.
Version: 7.5.503 / Virus Database: 269.16.11/1161 - = Release Date:=20 30/11/2007 12:12 PM
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