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 2554319 for flyrotary@lancaironline.net; Mon, 03 Dec 2007 18:45:23 -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 smtpout02.vgs.untd.com with SMTP id AABDXKFHHAP6SSUJ for (sender ); Mon, 3 Dec 2007 15:44:39 -0800 (PST) Message-ID: <2609B4566F134ACBA6555BA92AE63AB0@Penny> From: "Al Wick" To: "Rotary motors in aircraft" References: In-Reply-To: Subject: Re: [FlyRotary] Re: Giving up on single rotor Date: Mon, 3 Dec 2007 15:43:26 -0800 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_00DA_01C835C3.3ED60F50" 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: 40:20:2675315861 X-MAIL-INFO:4f858504112571797414b904d9b98075454130b940a4351d11403041408140151929c4898521045d047d113980e101397925f529ed6d34bdd9d5010580f56d8410e9ad91cd81e0313d20ad94a5f050d9712920c051f98dc9e5c965c161a075f07050312424fdd0a45179942d407de420b124f45d6d94edaddd38305d81401519 X-UNTD-OriginStamp: L941HVjjYzDhN3itp//mkIzhLqwChnIRg5iK70skGATz8K6fkGl+5w== X-UNTD-Peer-Info: 10.181.42.32|smtpout02.vgs.untd.com|smtpout02.vgs.untd.com|alwick@juno.com This is a multi-part message in MIME format. ------=_NextPart_000_00DA_01C835C3.3ED60F50 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MessageI don't have any expertise on this subject. But I do play around = with harmonic vibrations all the time in physics lab. I understand = aspects from statistical point of view too. Here's my wild theory: Apply torque wrench to the damper. Also measure the angle of that wrench = as you apply torque. You would end up with chart that says: at 1 degree, = you have 5 lbs. At 3 degrees you have 18 lbs. Etc. If you change the = durometer of ONE of your dampers, you change the above numbers AND the = frequency response of the unit. Using above numbers you should be able = to predict effect and test a whole bunch of frequency responses. That = would allow you to tune the device to optimize the damping. It gets you = away from the "Aha!" approach of experimenting. Converts your ideas into = numbers.=20 Just an idea. I could be totally full of it. -al wick ----- Original Message -----=20 From: George Lendich=20 To: Rotary motors in aircraft=20 Sent: Sunday, December 02, 2007 3:05 PM Subject: [FlyRotary] Re: Giving up on single rotor Al, 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 -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_00DA_01C835C3.3ED60F50 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message
I don't have any expertise on this = subject. But I=20 do play around with  harmonic vibrations all the time in physics = lab. I=20 understand aspects from statistical point of view too. Here's my wild=20 theory:
 
Apply torque wrench to the damper. Also = measure the=20 angle of that wrench as you apply torque. You would end up with chart = that says:=20 at 1 degree, you have 5 lbs. At 3 degrees you have 18 lbs. Etc. If you = change=20 the durometer of ONE of your dampers, you change the above numbers AND = the=20 frequency response of the unit. Using above numbers you should be able = to=20 predict effect and test a whole bunch of frequency responses. That would = allow=20 you to tune the device to optimize the damping. It gets you away from = the "Aha!"=20 approach of experimenting. Converts your ideas into numbers. =
 
Just an idea. I could be totally full = of=20 it.
 
-al wick
----- Original Message -----
From:=20 George=20 Lendich
Sent: Sunday, December 02, 2007 = 3:05=20 PM
Subject: [FlyRotary] Re: Giving = up on=20 single rotor

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
To: Rotary motors in = aircraft=20
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=20 think it would be better to measure torque vs. angle of deflection. = Using=20 torque wrench and simple angle measure device. If you graphed this, = you=20 would end up with a chart that defines frequency response of the = damper.=20 Goal to have damper frequency response that's out of phase with the = worst=20 torsional pulses.
 
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 = system.
 
I've always been drawn to having = damper that=20 has more than one frequency response. You never see designs like = that. So=20 with mild TV, it would respond one way. Suddenly it would have = different=20 response with larger TV. Both responses out of phase. They use this = method=20 with electronics and I've seen a few auto clutch dampers utilizing = the=20 concept.
 
FWIW
 
al wick
----- Original Message ----- =
From:=20 George Lendich
To: Rotary motors in = aircraft=20
Sent: Saturday, December = 01, 2007=20 10:46 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=20 Centaflex coupler that's only available in 50 and 60 = durometer. =20 It's a fairly large diameter, and thick coupler.  50 was = better=20 than 60, but two 50's (effectively 25) in series was way too=20 soft.  Maybe a 40 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=20 perhaps they already have the right damper for the = job.  I=20 also suspect his engine has softer power pulses at low = rpms.  It's=20 a 12A for one, and PP for another.  PP is great at high = rpms, but=20 not know for good 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=20 lift and cam timing.
Artificial intelligence in cockpit, N9032U = 240+=20 hours from Portland, Oregon
Glass panel design, Subaru install, = Prop=20 construct, Risk assessment info:
htt= p://www.maddyhome.com/canardpages/pages/alwick/index.html

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_00DA_01C835C3.3ED60F50--