X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail26.syd.optusnet.com.au ([211.29.133.167] verified) by logan.com (CommuniGate Pro SMTP 5.0.8) with ESMTPS id 973020 for flyrotary@lancaironline.net; Mon, 06 Feb 2006 22:07:21 -0500 Received-SPF: none receiver=logan.com; client-ip=211.29.133.167; envelope-from=lendich@optusnet.com.au Received: from george (d220-236-186-237.dsl.nsw.optusnet.com.au [220.236.186.237]) by mail26.syd.optusnet.com.au (8.12.11/8.12.11) with SMTP id k1736SFZ025105 for ; Tue, 7 Feb 2006 14:06:31 +1100 Message-ID: <002101c62b93$7de53cc0$edbaecdc@george> From: "george lendich" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Single rotor smooth as silk now Date: Tue, 7 Feb 2006 13:06:28 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_001E_01C62BE7.4EE30B60" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1106 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 This is a multi-part message in MIME format. ------=_NextPart_000_001E_01C62BE7.4EE30B60 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message Would a single with no dampers put the resonance beyond the useful range? Good question Ernest. I thought about trying the RD-1C drive with a = solid plug where the rubber dampeners normally live, but when I = considered that all the normal gear lash play would still be there, I = realized it was probably not going to be much of a test. =20 How much gear lash is there on a typical Hirth, or Rotax gear box? =20 Cheers, Rusty=20 There are two issues to cope with, one is resonances and the other = is transferring the torque pulses. The torque pulses are transferred = completely in a indefinitly stiff system. We do not want that, because = of the internal forces involved. That leaves the resonances created by = coupling and element flexing properties. I believe the only way to stay = out of the resonances is to keep them low. This is what ROTAX is doing, = a 582 has gear rattling around idle. When you watch a ROTAX starting up = it is very obvious when the rattling occurs. I have not observed any = rattle on my C-Box with the SOOB. My ROTAX C box has about 1/8" gear lash at the tip of th 72" prop. I = have seen the same on others, seems to be normal. Richard Sohn N-2071U Richard,=20 Do you have a photo of that donut type damper - is it similar to the = BMW type?=20 Have a look on the internet for Lord Dynaflex Couplings, that's what = Don Dunbar is using and sounds like it is ideal for the single rotor, I = prefer Tracy's set-up for the 2 rotor. George ( down under) ------=_NextPart_000_001E_01C62BE7.4EE30B60 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message
 

Would a single with no dampers put the = resonance
beyond=20 the useful range?

Good = question Ernest.  I thought about trying the RD-1C drive = with a=20 solid plug where the rubber dampeners normally live, but when I = considered=20 that all the normal gear lash play would still be there, I = realized it=20 was probably not going to be much of a test.  =
 
How much gear lash is there = on a typical=20 Hirth, or Rotax gear box? 
 
Cheers,
Rusty
 
 

There are two issues to cope with, one is = resonances and=20 the other is transferring the torque pulses. The torque pulses are=20 transferred completely in a indefinitly stiff system. We do not want = that,=20 because of the internal forces involved. That leaves the resonances = created=20 by coupling and element flexing properties. I believe the only way = to stay=20 out of the resonances is to keep them low. This is what ROTAX is = doing, a=20 582 has gear rattling around idle. When you watch a ROTAX starting = up it is=20 very obvious when the rattling occurs. I have not observed any = rattle on my=20 C-Box with the SOOB.

My ROTAX C box has about 1/8" gear = lash at the=20 tip of th 72" prop. I have seen the same on others, seems to be=20 normal.
 
Richard = Sohn
N-2071U
 
Richard,
Do you have a photo of that donut = type damper -=20 is it similar to the BMW type? 
Have a look on the internet for = Lord Dynaflex=20 Couplings, that's what Don Dunbar is using and sounds like it is = ideal for=20 the single rotor, I prefer Tracy's set-up for the 2 = rotor.
George ( down under)
 
 



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