X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail.globalsuite.net ([69.46.103.200] verified) by logan.com (CommuniGate Pro SMTP 5.2.0) with SMTP id 2784501 for flyrotary@lancaironline.net; Sun, 09 Mar 2008 18:25:27 -0400 Received-SPF: none receiver=logan.com; client-ip=69.46.103.200; envelope-from=rusty@radrotary.com X-AuditID: c0a8013c-aa0fcbb000004b31-0b-47d463aeb302 Received: from DELLRD1 (unknown [209.114.234.11]) by mail.globalsuite.net (Symantec Mail Security) with ESMTP id 8AA6E4DC007 for ; Sun, 9 Mar 2008 16:24:46 -0600 (MDT) From: "Russell Duffy" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: direct drive- was Re: Anyone have an RD-1C for sale? Date: Sun, 9 Mar 2008 06:24:09 -0500 Message-ID: <003f01c881d8$19559fa0$09b812c6@DELLRD1> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0040_01C881AE.307F97A0" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6626 Importance: Normal In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3198 X-Brightmail-Tracker: AAAAAA== This is a multi-part message in MIME format. ------=_NextPart_000_0040_01C881AE.307F97A0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Bobby answered the "how much HP" question with the HP chart =20 Thanks for the chart Bobby.=20 =20 - Looked like 112 HP at 4000 to me which is the RPM I would target. = That was also with a stock manifold. With an intake manifold optimized for = 4000 and adding a few ponies for a less restrictive exhaust system, I think = 120 is do-able. And I think it could come in at least 50 lbs lighter than a = Lyc O - 320. Another 5 or more pounds off the prop too. And that's = normally aspirated. Turboing to 150 HP would be conservative. =20 Only down side is the ~ 56 - 58" prop you would have to use. That would cost some takeoff & climb performance.=20 =20 This is all interesting, but I still think the geared single rotor is a better choice for the 100 HP range. It will definitely be lighter than = the direct drive two rotor, and will allow standard aircraft prop RPM's. It = too can be turboed to 150 HP with ease if that's what you need. There's = only that nasty torque reversal to deal with, but certainly that can be = worked out. Once above 3000 rpm, it's smooth as silk assuming proper = balancing. =20 =20 When thinking about the weight, don't forget that you don't give up the = full weight of the redrive. You will still have to have an external thrust bearing and prop hub, as well as a way to hold the starter. I'm = guessing you might only save 30 lbs over the weight of a redrive, but you'll be losing half the power. Doesn't seem like a very good deal to me. =20 =20 Tracy (why the hell am I talking people out of gear drives :>)=20 =20 I'm not sure you "have" talked anyone out of a gear drive yet :-) =20 Rusty (thawing in the hotel) =20 =20 ------=_NextPart_000_0040_01C881AE.307F97A0 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Message
Bobby answered the "how much HP" question with the HP chart
 
Thanks for the chart=20 Bobby. 
 
  - Looked like 112 HP = at 4000=20 to me which is the RPM I would target.  That was also with a = stock=20 manifold.  With an intake manifold optimized for 4000 and = adding a few=20 ponies for a less restrictive exhaust system, I think 120 is = do-able. =20 And I think it could come in at least 50 lbs lighter than a = Lyc O=20 - 320.  Another 5 or more pounds off the prop too.  = And=20 that's normally aspirated.  Turboing to 150 HP would be = conservative.
 
Only down side is the ~ 56 - 58" prop you would have to use.  = That=20 would cost some takeoff & climb performance. 
 
This is all=20 interesting, but I still think the geared single rotor is a better = choice for=20 the 100 HP range.  It will definitely be lighter than the direct = drive two=20 rotor, and will allow standard aircraft prop RPM's.  It too can be = turboed=20 to 150 HP with ease if that's what you need.  There's only that = nasty=20 torque reversal to deal with, but certainly that can be worked = out.  Once=20 above 3000 rpm, it's smooth as silk assuming proper=20 balancing.  
 
When thinking=20 about the weight, don't forget that you don't give up the full = weight of=20 the redrive.  You will still have to have an external = thrust=20 bearing and prop hub, as well as a way to hold the starter.  = I'm=20 guessing you might only save 30 lbs over the weight of a redrive, = but=20 you'll be losing half the power.  Doesn't seem like a very good = deal to=20 me.  
 
Tracy  (why the hell am I talking people out of gear drives=20 :>) 
 
I'm not sure=20 you "have" talked anyone out of a gear drive yet :-)
 
Rusty=20 (thawing in the hotel)
 
 
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