X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from wr-out-0506.google.com ([64.233.184.230] verified) by logan.com (CommuniGate Pro SMTP 5.1c.4) with ESMTP id 1409867 for flyrotary@lancaironline.net; Tue, 19 Sep 2006 08:39:04 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.233.184.230; envelope-from=russell.duffy@gmail.com Received: by wr-out-0506.google.com with SMTP id i22so1546615wra for ; Tue, 19 Sep 2006 05:38:24 -0700 (PDT) DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:from:to:subject:date:message-id:mime-version:content-type:x-priority:x-msmail-priority:x-mailer:x-mimeole:importance:in-reply-to; b=HRDO4NHWyS1xPTzc8bnLqnLRU7Mh/HrNhUDfp2rvFFAOpCspn5D+ZmxTN/P+zhR0yEy6F+vM3qpJTP6YLxum8ffeKNig0ttYgmkqZ8P7O7YFUUDVwetT1CkXHaXpBRyBYSVXIXjwLp/65PaiVlVkBugWHG7YR9fDg5LSe+Hees4= Received: by 10.90.54.20 with SMTP id c20mr5233579aga; Tue, 19 Sep 2006 05:36:36 -0700 (PDT) Return-Path: Received: from rd ( [65.6.194.9]) by mx.gmail.com with ESMTP id 8sm1319647wrl.2006.09.19.05.36.36; Tue, 19 Sep 2006 05:36:36 -0700 (PDT) From: "Russell Duffy" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] ducted fans Date: Tue, 19 Sep 2006 07:36:35 -0500 Message-ID: <001c01c6dbe8$3f4770e0$6101a8c0@rd> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_001D_01C6DBBE.567168E0" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6626 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2962 Importance: Normal In-Reply-To: This is a multi-part message in MIME format. ------=_NextPart_000_001D_01C6DBBE.567168E0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable One definition of the difference between "shrouded propellor" and = "ducted fan", is the ducted fan has a duct longer than the fan diameter. My = shroud was only 24" long while the fan was 38" in diameter. For your gyro application, I would think it would still be a shrouded propellor, as I doubt you have room for a long duct.=20 =20 Hi Perry, =20 Good to hear from you. I'm sure I'll have lots of questions if I get to = the point of trying this, but for now I'm mostly curious about the weight comparison between fan and prop. When you changed from fan to = PSRU/prop, did the plane end up heavier? =20 =20 The stock single rotor configuration is already plagued by excess = weight, so one of my hopes was that this would reduce it some. At least the fan = unit would be a bit smaller than what you were using, so a bit lighter too. = You are also correct that I wouldn't have room for for a long enough duct to = be a "ducted fan". =20 =20 Thanks, Rusty (must forget this long enough to finish the RV-8) =20 ------=_NextPart_000_001D_01C6DBBE.567168E0 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Message
One definition of the difference between "shrouded propellor" and = "ducted=20 fan", is the ducted fan has a duct longer than the fan diameter. My = shroud was=20 only 24" long while the fan was 38" in diameter. For your gyro = application, I=20 would think it would still be a shrouded propellor, as I doubt you have = room for=20 a long duct. 
 
Hi=20 Perry,
 
Good to hear=20 from you.  I'm sure I'll have lots of questions if I get to the = point of=20 trying this, but for now I'm mostly curious about the weight comparison = between=20 fan and prop.  When you changed from fan to PSRU/prop, did the = plane end up=20 heavier? 
 
The stock=20 single rotor configuration is already plagued by excess weight, so one=20 of my hopes was that this would reduce it some.  At least the = fan unit=20 would be a bit smaller than what you were using, so a bit lighter = too.  You=20 are also correct that I wouldn't have room for for a long enough duct to = be a=20 "ducted fan".     
 
Thanks,
Rusty (must=20 forget this long enough to finish the RV-8)
 
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