X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail06.syd.optusnet.com.au ([211.29.132.187] verified) by logan.com (CommuniGate Pro SMTP 5.2c1) with ESMTPS id 2556201 for flyrotary@lancaironline.net; Tue, 04 Dec 2007 17:21:54 -0500 Received-SPF: none receiver=logan.com; client-ip=211.29.132.187; envelope-from=lendich@optusnet.com.au Received: from george (d211-31-234-154.dsl.nsw.optusnet.com.au [211.31.234.154]) by mail06.syd.optusnet.com.au (8.13.1/8.13.1) with SMTP id lB4ML73U008839 for ; Wed, 5 Dec 2007 09:21:08 +1100 Message-ID: <005501c836c3$fb23a900$9aea1fd3@george> From: "George Lendich" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Giving up on single rotor Date: Wed, 5 Dec 2007 08:21:11 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0052_01C83717.CB869730" 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_0052_01C83717.CB869730 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable TJ, I have heard of something similar, but have never seen one. The rattler = does look good, so I have shot off a request on pricing and asked if = they had something for the single rotor ( for off-road recreational = use). Their in Memphis, Tennessee - if anyone is handy to them there parts. George ( down under) To quote Al, "I might be full of it", .... but: A couple of years ago, when I started to read up on all the fantastic = aftermarket gadgets available and legal to the US folks (I am from = Europe and modifying vehicles is a PITA MAJOR), I read about a = vibration/torque pulse damper that consisted of a rather massive ring = with holes (don't remember if they where evenly spaced or not...) the = holes where filled with rolls (cylindrical), with what seemed of = different sizes. The rolls where free to roll around inside their = specific hole. obviously once the crank started to turn the rolls would be drawn to = the outside, but depending on the torque pulses they would roll back and = forth inside the holes, supposedly dampening (?) vibration/torque = pulses. Supposedly a development from WW II aircraft engines. Usable only with even number cylinder engines and even firing order = engines.. On the site below this thing is called a pendulum absorber?? See:=20 http://www.tciauto.com/Products/Rattler/ Lynn, Bill, George, Richard - anyone knows what I am talking about? = Any possible application for the 1-rotor?=20 Am I full of it?? TJ On 12/4/07, George Lendich wrote: Ok Al, I can understand that now that you have explained it further. All we have to do is marry up the frequency of the single rotor, one = pulse per shaft rotation, to that of a known damper. We know that the more outward (to the edge of the flexplate) and the = softer the damper the better for the 2 rotor, 2 pulses per shaft = rotation . I believe that Richard's suggestion that the damper for the single = be closer to the centre of the flexplate. George (down under) I 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=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=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 -------------------------------------------------------------------------= ----- 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_0052_01C83717.CB869730 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
TJ,
I have heard of something similar, but = have never=20 seen one. The rattler does look good, so I have shot off a request on = pricing=20 and asked if they had something for the single rotor ( for off-road = recreational=20 use).
Their in Memphis, Tennessee - if anyone = is handy to=20 them there parts.
George ( down under)
To=20 quote Al,

"I might be full of it", .... but:
A couple of = years ago,=20 when I started to read up on all the fantastic aftermarket gadgets = available=20 and legal to the US folks (I am from Europe and modifying vehicles is = a PITA=20 MAJOR), I read about a vibration/torque pulse damper that consisted = of  a=20 rather massive ring with holes (don't remember if they where evenly = spaced or=20 not...) the holes where filled with rolls (cylindrical), with what = seemed of=20 different sizes. The rolls where free to roll around inside their = specific=20 hole.
obviously once the crank started to turn the rolls would be = drawn to=20 the outside, but depending on the torque pulses they would roll back = and forth=20 inside the holes, supposedly dampening (?) vibration/torque pulses. = Supposedly=20 a development from WW II aircraft engines.
Usable only with even = number=20 cylinder engines and even firing order engines..
On the site below = this=20 thing is called a pendulum absorber??

See:

http://www.tciauto.com/= Products/Rattler/


Lynn,=20 Bill, George, Richard - anyone knows what I am talking about? Any = possible=20 application for the 1-rotor?
Am I full of it??

TJ

On 12/4/07, George=20 Lendich <lendich@optusnet.com.au>=20 wrote:
Ok Al,
I can understand that now that you = have=20 explained it further.
 
All we have to do is marry up the = frequency of=20 the single rotor, one pulse per shaft rotation, to that of a = known=20 damper.
 
We know that the more outward (to = the edge of=20 the flexplate) and the softer the damper the better for the 2 = rotor, 2=20 pulses per shaft rotation .
 
I believe that Richard's suggestion = that the=20 damper for the single be closer to the centre of the = flexplate.
 
George (down under)
I don't have any expertise on = this subject.=20 But I do play around with  harmonic vibrations all the time = in=20 physics lab. I understand aspects from statistical point of view = too.=20 Here's my wild theory:
 
Apply torque wrench to the = damper. Also=20 measure the angle of that wrench as you apply torque. You would = end up=20 with chart that says: at 1 degree, you have 5 lbs. At 3 degrees = you have=20 18 lbs. Etc. If you change the durometer of ONE of your dampers, = you=20 change the above numbers AND the frequency response of the unit. = Using=20 above numbers you should be able to predict effect and test a = whole bunch=20 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.
 
Just an idea. I could be totally = full of=20 it.
 
-al wick
-----=20 Original Message -----
From:=20 George = Lendich=20
To:=20 Rotary motors in=20 aircraft
Sent:=20 Sunday, December 02, 2007 3:05 PM Subject:=20 [FlyRotary] Re: Giving up on single rotor

Al,
It sounds like you might be = right - but I=20 wish I had an idea of what your talking about in regard to = torque V=20 angle of deflection.
I do my best but you have me = beat on this=20 one.
George ( down = under)
-----=20 Original Message ----- From:=20 Al Wick = To:=20 Rotary motors=20 in aircraft Sent:=20 Monday, December 03, 2007 1:19 AM Subject:=20 [FlyRotary] Re: Giving up on single rotor

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

Righ-t-o = Rusty!
Thanks
George ( down = under)
So what durometer = is your gut=20 feeling now that you went this far? 
 
Hi George,
 
I don't think you can compare the durometer of = one damper=20 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=20 durometer.  It's a fairly large diameter, and thick=20 coupler.  50 was better than 60, but two 50's = (effectively=20 25) in series was way too soft.  Maybe a 40 = would be=20 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. =20 I also suspect his engine has softer power pulses at low=20 rpms.  It's a 12A for one, and PP for another.  = PP is=20 great at high rpms, but not know for good power down=20 low.  It's the best theory I=20 have.  
 
Cheers,
Rusty  

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

-Al Wick
Cozy IV powered by Turbo Subaru 3.0R with = variable=20 valve lift and cam timing.
Artificial intelligence in = cockpit,=20 N9032U 240+ hours from Portland, Oregon
Glass panel design, = Subaru=20 install, Prop construct, Risk assessment info:
http://www.maddyhome.com/canardpages/pages/alwick/index.h= tml=20

No virus found in this incoming message.
Checked by = AVG Free=20 Edition.
Version: 7.5.503 / Virus Database: 269.16.11/1161 = -=20 Release 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:
http://www.maddyhome.com/canardpages/pages/alwick/index.h= tml=20

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


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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