X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail31.syd.optusnet.com.au ([211.29.132.102] verified) by logan.com (CommuniGate Pro SMTP 5.1.9) with ESMTPS id 2084023 for flyrotary@lancaironline.net; Mon, 04 Jun 2007 18:28:13 -0400 Received-SPF: none receiver=logan.com; client-ip=211.29.132.102; envelope-from=lendich@optusnet.com.au Received: from george (d220-237-235-238.dsl.nsw.optusnet.com.au [220.237.235.238]) by mail31.syd.optusnet.com.au (8.13.1/8.13.1) with SMTP id l54MRSnX011043 for ; Tue, 5 Jun 2007 08:27:30 +1000 Message-ID: <003b01c7a6f7$8bb4e6d0$eeebeddc@george> From: "George Lendich" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Single rotor video Date: Tue, 5 Jun 2007 08:27:31 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0038_01C7A74B.5C0C1530" 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_0038_01C7A74B.5C0C1530 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message Rusty, I will leave the video for a couple of days so as to not bog down your = ISP. However I have had a long time to consider Dampers and have gone for the = polyurethane type (about 90 shore) as this has been tried on a 4 = cylinder and has been on the internet somewhere and showed up on the of = the discussion groups and in Contact mag I believe. I know that Tracy suggests the softer the better but it's a 2 rotor and = with no toque reversals -that's understandable. The article suggested softer rubber dampers turned to dust in short = order. The reason is, I believe, the distance between +ve and -ve torque = responses is much longer and the damper is caught going one way when it = is forced to go another ( in layman's language). For this reason I = believe the stiffer dampers less inclined to travel as far, as quickly. =20 The material I have selected is readily available and I purchased 300mm = for $30. This is the stuff they make for the aftermarket 4WD spring = mounts. Also Tracy suggests the more toward the outer edge of the flywheel the = better for mounting the 2 rotor mounting - again understandable. However = for the larger torque fluctuations, I believe it logical that the closer = toward the centre with limit the travel. Hope that helps. George ( down under) Greetings, I made a short video yesterday of a single rotor run. The purpose was = to demonstrate and document the prop tip behavior with the stock rubber = coupler/damper, so I can see if it gets any better with the new softer = one. =20 As you can see, it gets pretty wild at times, particularly when = changing rpms. I'm not sure this is completely abnormal though, because = I've watched the Subaru engines on the RAF2000 gyro do the exact same = thing. They even have a bit of tip wandering too, so some of this may = be OK.=20 During the video, you'll hear me say 2600 rpm, and at that point, the = tips are wandering fore and aft a bit. The next rpm tested was 3500, = and it appears fairly smooth. You'll note that my throttle control = doesn't have much friction, and closes itself if I don't hold it. By = the time I say 3500 rpm into the camera, you can see that the engine has = slowed down considerably, so 3500 is the point where I get up to come = back to the camera, not when I say 3500. For that reason, 4000 rpm = became a hand signal, and appears perfectly smooth. =20 The video is 60 MB, so not for the dialup crowd unless you download it = overnight. Also, if there's more traffic than I expect, I may have to = shut the link down to preserve my web space quota for the month. =20 http://www.radrotary.com/WL_original_damper.wmv Rusty=20 ------=_NextPart_000_0038_01C7A74B.5C0C1530 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message
 Rusty,
 I will leave the video for a = couple of days=20 so as to not bog down your ISP.
However I have had a long time to = consider Dampers=20 and have gone for the polyurethane type (about 90 shore) as this has = been tried=20 on a 4 cylinder and has been on the internet somewhere and showed up on = the of=20 the discussion groups and in Contact mag I believe.
 
I know that Tracy suggests the softer = the better=20 but it's a 2 rotor and with no  toque reversals  -that's=20 understandable.
 
The article suggested softer rubber = dampers turned=20 to dust in short order.
The reason is, I believe, the distance = between +ve=20 and -ve torque responses is much longer and the damper is caught going = one way=20 when it is forced to go another ( in layman's language). For this reason = I=20 believe the stiffer dampers less inclined to travel as far, as=20 quickly.
 
The material I have selected is readily = available=20 and I purchased 300mm for $30. This is the stuff they make for the = aftermarket=20 4WD spring mounts.
 
Also Tracy suggests the more toward the = outer edge=20 of the flywheel the better for mounting the 2 rotor mounting - again=20 understandable. However for the larger torque fluctuations, I believe it = logical=20 that the closer toward the centre with limit the travel.
 
Hope that helps.
George ( down under)
Greetings,
 
I made a = short video=20 yesterday of a single rotor run.  The purpose was to demonstrate = and=20 document the prop tip behavior with the stock rubber coupler/damper, = so I can=20 see if it gets any better with the new softer one.  =20
 
As you can = see, it gets=20 pretty wild at times, particularly when changing rpms.  I'm not = sure this=20 is completely abnormal though, because I've watched the Subaru engines = on the=20 RAF2000 gyro do the exact same thing.  They even have a bit of = tip=20 wandering too, so some of this may be OK.
 
During the = video, you'll=20 hear me say 2600 rpm, and at that point, the tips are wandering fore = and aft a=20 bit.  The next rpm tested was 3500, and it appears fairly = smooth. =20 You'll note that my throttle control doesn't have much friction, = and=20 closes itself if I don't hold it.  By the time I say 3500 rpm = into the=20 camera, you can see that the engine has slowed down considerably, so = 3500 is=20 the point where I get up to come back to the camera, not when I say=20 3500.  For that reason, 4000 rpm became a hand signal, and = appears=20 perfectly smooth.     
 
The video is = 60 MB, so=20 not for the dialup crowd unless you download it overnight.  Also, = if=20 there's more traffic than I expect, I may have to shut the link down = to=20 preserve my web space quota for the month. 
 
http://www.radro= tary.com/WL_original_damper.wmv
 
Rusty=20
 
 
 
 
------=_NextPart_000_0038_01C7A74B.5C0C1530--