X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from smtp102.vzn.mail.mud.yahoo.com ([68.142.203.46] verified) by logan.com (CommuniGate Pro SMTP 5.1c.4) with SMTP id 1409901 for flyrotary@lancaironline.net; Tue, 19 Sep 2006 09:06:34 -0400 Received-SPF: pass receiver=logan.com; client-ip=68.142.203.46; envelope-from=pjmick@verizon.net Received: (qmail 63910 invoked from network); 19 Sep 2006 13:05:50 -0000 Received: from unknown (HELO ?192.168.1.44?) (pjmick@verizon.net@71.111.117.25 with plain) by smtp102.vzn.mail.mud.yahoo.com with SMTP; 19 Sep 2006 13:05:50 -0000 Message-ID: <450FEB95.1040400@verizon.net> Date: Tue, 19 Sep 2006 06:07:33 -0700 From: Perry Mick User-Agent: Mozilla/5.0 (Windows; U; Win98; en-US; rv:1.7.2) Gecko/20040804 Netscape/7.2 (ax) X-Accept-Language: en-us, en MIME-Version: 1.0 To: flyrotary@lancaironline.net Subject: RE: [FlyRotary] ducted fans Content-Type: multipart/alternative; boundary="------------050201020405000101080709" This is a multi-part message in MIME format. --------------050201020405000101080709 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit 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. Hi Perry, 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? 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". Thanks, Rusty (must forget this long enough to finish the RV-8) The PSRU/prop installation came out lighter than the ducted fan, but it wouldn't have to be so. I was lugging around the stock heavy manual transmission flywheel and my duct was overbuilt and too heavy. Perry --------------050201020405000101080709 Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: 7bit

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.

Hi Perry,

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?

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".

Thanks,

Rusty (must forget this long enough to finish the RV-8)

The PSRU/prop installation came out lighter than the ducted fan, but it wouldn't have to be so. I was lugging around the stock heavy manual transmission flywheel and my duct was overbuilt and too heavy.

Perry

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