X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from wx-out-0506.google.com ([66.249.82.229] verified) by logan.com (CommuniGate Pro SMTP 5.1c.4) with ESMTP id 1406919 for flyrotary@lancaironline.net; Sun, 17 Sep 2006 09:54:02 -0400 Received-SPF: pass receiver=logan.com; client-ip=66.249.82.229; envelope-from=russell.duffy@gmail.com Received: by wx-out-0506.google.com with SMTP id i29so3583739wxd for ; Sun, 17 Sep 2006 06:53:22 -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:importance:x-mimeole; b=YCw+5hERza92AO1O/MqttJbIyb+uNwEtHFjlbZRPozV2xeIzdgQzFq81YpVQWtbNq8+tO891z8ErXPZlli43LgXOmbvcg7bKpvjUyu4jJzWJVwTTOUDTCH/i0cSC47BPTkzYLbzG+aXZU3UkbYgAhfMzRQtTkjkK0VWjK1iv2ck= Received: by 10.70.96.3 with SMTP id t3mr18177510wxb; Sun, 17 Sep 2006 06:53:21 -0700 (PDT) Return-Path: Received: from rd ( [65.6.194.9]) by mx.gmail.com with ESMTP id 7sm12876329wrh.2006.09.17.06.53.20; Sun, 17 Sep 2006 06:53:21 -0700 (PDT) From: "Russell Duffy" To: "Flyrotary List" Subject: ducted fan questions Date: Sun, 17 Sep 2006 08:53:21 -0500 Message-ID: <000001c6da60$a3951590$6101a8c0@rd> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0001_01C6DA36.BABF0D90" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6626 Importance: Normal X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2962 This is a multi-part message in MIME format. ------=_NextPart_000_0001_01C6DA36.BABF0D90 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Greetings, =20 I'm still thinking of using the single rotor engine for a gyrocopter, = and started considering the possibility of using a ducted fan to eliminate a couple problems. =20 Problem one is the lack of a proven redrive for the single rotor, and problem two is height of most gyros. Since the rotor has to clear the pusher prop, the mast ends up being really tall, and the prop is usually shortened as much as possible. This means you end up with an 8+ ft = high gyro that won't fit in the garage, and a short 60" prop which is far = less than ideal for thrust. =20 =20 I know nothing about ducted fans, so I'm looking for a bit of a reality check. If I want to run direct drive blades at 7500 rpm, it looks like = I need to keep them around 32" in diameter to stay around .9 mach. This = seems really short, but short is great as long as it works. =20 =20 Can anyone venture a guess as to how long the fan unit would have to be? Would it end up being as heavy as a redrive, or is there weight to be = saved. =20 Thanks for any thoughts. It may just be a wild and crazy idea, but I = had to ask. =20 =20 Cheers, Rusty (out of touch till evening) =20 ------=_NextPart_000_0001_01C6DA36.BABF0D90 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Message
Greetings,
 
I'm still = thinking of using=20 the single rotor engine for a gyrocopter, and started = considering the=20 possibility of using a ducted fan to=20 eliminate a couple problems.
 
Problem one is = the lack of=20 a proven redrive for the single rotor, and problem two is height of most = gyros.  Since the rotor has to clear the pusher prop, the mast ends = up=20 being really tall, and the prop is usually shortened as much as=20 possible.   This means you end up with an 8+ ft high gyro that = won't=20 fit in the garage, and a short 60" prop which is far less than ideal for = thrust. 
 
I know nothing = about ducted=20 fans, so I'm looking for a bit of a reality check.  If I want to = run direct=20 drive blades at 7500 rpm, it looks like I need to keep them around 32" = in=20 diameter to stay around .9 mach.  This seems really short, but = short=20 is great as long as it works.  
 
Can anyone = venture a guess=20 as to how long the fan unit would have to be?  Would it end up = being=20 as heavy as a redrive, or is there weight to be = saved.
 
Thanks for any=20 thoughts.  It may just be a wild and crazy idea, but I had to=20 ask.  
 
Cheers,
Rusty (out of = touch=20 till evening)   
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