X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from poplet2.per.eftel.com ([203.24.100.45] verified) by logan.com (CommuniGate Pro SMTP 5.2.16) with ESMTP id 3878227 for flyrotary@lancaironline.net; Wed, 07 Oct 2009 17:05:14 -0400 Received-SPF: none receiver=logan.com; client-ip=203.24.100.45; envelope-from=lendich@aanet.com.au Received: from sv1-1.aanet.com.au (sv1-1.per.aanet.com.au [203.24.100.68]) by poplet2.per.eftel.com (Postfix) with ESMTP id 63A52173912 for ; Thu, 8 Oct 2009 05:04:36 +0800 (WST) Received: from ownerf1fc517b8 (203.171.92.134.static.rev.aanet.com.au [203.171.92.134]) by sv1-1.aanet.com.au (Postfix) with SMTP id 0A2E5BEC015 for ; Thu, 8 Oct 2009 05:04:35 +0800 (WST) Message-ID: <4EB9C764D068411193DB7BC1349ABFA9@ownerf1fc517b8> From: "George Lendich" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Balls and Springs Date: Thu, 8 Oct 2009 07:04:36 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0013_01CA47E5.989D9EF0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5843 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 X-Antivirus: avast! (VPS 091007-0, 10/07/2009), Outbound message X-Antivirus-Status: Clean This is a multi-part message in MIME format. ------=_NextPart_000_0013_01CA47E5.989D9EF0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Lynn, Thanks, I have spun up the rotor in a lathe and filled the rotor with = coolant from a spray bottle, being careful not to spill any and then = weighing the remainder and comparing it to the original weight (similar = system to what you suggest). I went the extra mile and then adjusted the = weight by comparing it to oil weight of the same volume. I did speak to Richard Sohn at the time but at that stage he wasn't to = concerned with balancing to that extent with his demonstrator. It has also been suggested that the apex seal and springs be excluded as = their weight is borne by the rotor housing. Then again I've had people argue against those suggestions. I thought any out of balance might exacerbate the negative torque = pulses, but your saying because their so large it's not such a concern = - which puts my mind to rest. I do like your suggestion of 'reverse engineering' the balancing = process, I think I will discuss that with a professional balancer. George (down under) Lynn, With balancing my single rotor, what would you suggest that I allow ( = percentage wise) for oil weight in the rotor - it was suggested to me = that I should allow full rotor oil weight. This discussion suggests otherwise. George ( down under) George, The process I saw on the internet came from Down there. A rotor is = spun up in the lathe with a plastic shield around the outside. Oil is = squirted in until it starts spilling out. A pan is slipped under the = rotor and the lathe stopped. (if your lathe has a coolant system that = would work as well with less mess) The weights are close enough. Then = the rotor is laid on a grill on the pan and allowed to drain. Then weigh = the liquid in the pan. I bet the balancing people just have a number on = the wall for rotaries that is close to that weight. A balancer could do = it backwards by spinning the shaft from a factory built engine, with the = counterweights mounted, and then add bobweight until he gets a balance. = Then subtract the rotor weight from the bobweight and that difference = would be the oil allowance.=20 The big name builders all balance to a gnats butt weight, but I just = get the rotor weights the same. Never a problem. The single pulse per = revolution will be so big that a small balance error will go unoticed. = But, its no sin to start out with the balance correct. I have thought = about singles and decided that as big a diameter flywheel that you can = fit but weighted only at the outer edge. Like 4 sets of starter rings = tiged to a flex plate. Even Mazda builds with pieces two weight ranges = apart. They have stamped the weights on rotors, and have used colored = paint dots. Of course the paint dots are gone when we see a used rotor.=20 Richard Sohn can tell you. He seems to be doing well with his. Lynn E. Hanover ------=_NextPart_000_0013_01CA47E5.989D9EF0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Lynn,
Thanks, I have spun up the rotor in a = lathe and=20 filled the rotor with coolant from a spray bottle, being careful not to = spill=20 any and then weighing the remainder and comparing it to the original = weight=20 (similar system to what you suggest). I went the extra mile and then = adjusted=20 the weight by comparing it to oil weight of the same = volume.
 
I did speak to Richard Sohn at the time = but at that=20 stage he wasn't to concerned with balancing to that extent with his=20 demonstrator.
 
It has also been suggested that the = apex seal and=20 springs be excluded as their weight is borne by the rotor=20 housing.
 
Then again I've had people argue = against those=20 suggestions.
 
I thought any out of balance might = exacerbate the=20 negative torque pulses, but your saying because their so large it's = not =20 such a concern - which puts my mind to rest.
 
I do like your suggestion of  = 'reverse=20 engineering' the balancing process, I think I will discuss that with a=20 professional balancer.
 
George (down=20 under)
 Lynn,
With balancing my single rotor, what = would you=20 suggest that I allow ( percentage wise) for oil weight in the rotor - = it was=20 suggested to me that I should allow full rotor oil weight.
This discussion suggests = otherwise.
George ( down under)
 
George,
 
The process = I saw on=20 the internet came from Down there. A rotor is spun up in the lathe = with a=20 plastic shield around the outside. Oil is squirted in until it starts = spilling=20 out. A pan is slipped under the rotor and the lathe stopped. (if your = lathe=20 has a coolant system that would work as well with less mess) The = weights are=20 close enough. Then the rotor is laid on a grill on the pan and allowed = to=20 drain. Then weigh the liquid in the pan. I bet the balancing people = just have=20 a number on the wall for rotaries that is close to that weight. A = balancer=20 could do it backwards by spinning the shaft from a factory built = engine, with=20 the counterweights mounted, and then add bobweight until he gets a = balance.=20 Then subtract the rotor weight from the bobweight and that difference = would be=20 the oil allowance.
 
The big = name builders=20 all balance to a gnats butt weight, but I just get the rotor weights = the same.=20 Never a problem. The single pulse per revolution will be so big that a = small=20 balance error will go unoticed. But, its no sin to start out with the = balance=20 correct. I have thought about singles and decided that as big a = diameter=20 flywheel that you can fit but weighted only at the outer edge. Like 4 = sets of=20 starter rings tiged to a flex plate. Even Mazda builds with pieces two = weight=20 ranges apart. They have stamped the weights on rotors, and have used = colored=20 paint dots. Of course the paint dots are gone when we see a used = rotor.=20
 
Richard = Sohn can tell=20 you. He seems to be doing well with his.
 
Lynn E.=20 Hanover
 
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