X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from [64.136.55.15] (HELO outbound-mail.dca.untd.com) by logan.com (CommuniGate Pro SMTP 5.2c1) with SMTP id 2551894 for flyrotary@lancaironline.net; Sun, 02 Dec 2007 10:22:12 -0500 Received-SPF: pass receiver=logan.com; client-ip=64.136.55.15; envelope-from=alwick@juno.com Received: from Penny (71-32-251-184.ptld.qwest.net [71.32.251.184]) by smtpout04.vgs.untd.com with SMTP id AABDXFVLFASWCPYS for (sender ); Sun, 2 Dec 2007 07:20:37 -0800 (PDT) Message-ID: From: "Al Wick" To: "Rotary motors in aircraft" References: In-Reply-To: Subject: Re: [FlyRotary] Re: Giving up on single rotor Date: Sun, 2 Dec 2007 07:19:27 -0800 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0080_01C834B3.AC443280" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Windows Mail 6.0.6000.16480 X-MimeOLE: Produced By Microsoft MimeOLE V6.0.6000.16545 X-ContentStamp: 21:10:3182952645 X-MAIL-INFO:19dbdb4adafaca639ab7934a73935b1f2aaff793bbba873fdabbf7afbb5fbb97abaebe9fdb134aaa4a5edadf5bfec3df63fa8bae07ef3a4f7317c36b5b8bef8e0fce7aeb6e5fb33b0bd77a5aa36f0e73caaed70a432b024ee74ee3cbbf7b1f6f670e3b2e2efb4bba43635aa7bb X-UNTD-OriginStamp: L941HVjjYzDhN3itp//mkG9I3WtdPICwXydEzgqZWqGxG+crmMNZRA== X-UNTD-Peer-Info: 10.181.42.34|smtpout04.vgs.untd.com|smtpout04.vgs.untd.com|alwick@juno.com This is a multi-part message in MIME format. ------=_NextPart_000_0080_01C834B3.AC443280 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MessageInstead 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. =20 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 ------=_NextPart_000_0080_01C834B3.AC443280 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message
Instead of using durometer in this = case. I think it=20 would be better to measure torque vs. angle of deflection. Using torque = wrench=20 and simple angle measure device. If you graphed this, you would end up = with a=20 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=20 then tune it with durometer tweaks. So you might end up with 2 dampers = at 50=20 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 mild=20 TV, it would respond one way. Suddenly it would have different response = with=20 larger TV. Both responses out of phase. They use this method with = electronics=20 and I've seen a few auto clutch dampers utilizing the concept. =
 
FWIW
 
al wick
----- Original Message -----
From:=20 George=20 Lendich
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 now=20 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 = hardness=20 of the rubber.  The Autoflight drive uses a stock Centaflex = coupler=20 that's only available in 50 and 60 durometer.  It's a fairly = large=20 diameter, and thick coupler.  50 was better than 60, but two = 50's=20 (effectively 25) in series was way too soft.  Maybe a 40 = would be=20 good, but it doesn't = 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
------=_NextPart_000_0080_01C834B3.AC443280--