Return-Path: <13brv3@bellsouth.net> Received: from imf18aec.mail.bellsouth.net ([205.152.59.66] verified) by logan.com (CommuniGate Pro SMTP 4.2.8) with ESMTP id 608650 for flyrotary@lancaironline.net; Sat, 15 Jan 2005 20:37:01 -0500 Received-SPF: pass receiver=logan.com; client-ip=205.152.59.66; envelope-from=13brv3@bellsouth.net Received: from rd ([65.6.194.9]) by imf18aec.mail.bellsouth.net (InterMail vM.5.01.06.11 201-253-122-130-111-20040605) with ESMTP id <20050116013632.VFPO2042.imf18aec.mail.bellsouth.net@rd> for ; Sat, 15 Jan 2005 20:36:32 -0500 From: "Russell Duffy" <13brv3@bellsouth.net> To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: IVO Prop Date: Sat, 15 Jan 2005 19:36:54 -0600 Message-ID: <000401c4fb6b$dbf31570$6101a8c0@rd> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0005_01C4FB39.9158A570" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6626 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2527 Importance: Normal In-Reply-To: This is a multi-part message in MIME format. ------=_NextPart_000_0005_01C4FB39.9158A570 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable I believe Tracey felt the reduced airfoil shape and/or reduced pitch = change of the prop root contributed to his lower top end performance. I was = hoping Tracy would jump into this discussion and refresh my memory. =20 =20 Tracy was planning to to to the RV fly-in in Lakeland this weekend, so = you won't hear from him right away. =20 =20 If the prop root profile was the cause for his lower performance, I am estimating this may not have an effect on my application since I am a = pusher and thrust contribution from the root area is likely to be small. The = only adverse effect this should have is on ground cooling, but I am planning = on exhaust augmenters to assist cooling.=20 =20 =20 I believe the issue is the root area as you recalled. The IVO is just a flat bar at that point, and creates a bunch of drag. I believe Tracy = wanted to try it again, but with some sort of cuffs added to the spinner to = improve the shape. FWIW, this problem also exists to some extent with our = monster props, since the center is also pretty flat. Tracy did in fact make a = funky looking cuff that smoothes out the root area of his new prop, and he = felt like it did make a measurable difference. I haven't done it, and I = don't think Ed has either. =20 =20 I had also speculated previously that pushers wouldn't be effected as = much, because the fuselage blocks much of the effected area. Al will be disappointed to hear that I have absolutely no engineering studies to = back that up :-) =20 =20 Cheers, Rusty (parts needed)=20 ------=_NextPart_000_0005_01C4FB39.9158A570 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Message
I believe Tracey felt the reduced = airfoil=20 shape and/or reduced pitch change of the prop root contributed = to his=20 lower top end performance.  I was hoping Tracy would jump into this = discussion and refresh my memory.  
 
Tracy was planning to to to the RV fly-in in = Lakeland=20 this weekend, so you won't hear from him right away.  
 
  If the=20 prop root profile was the cause for his lower performance, I am = estimating this=20 may not have an effect on my application since I am a pusher and thrust=20 contribution from the root area is likely to be small.  The only = adverse=20 effect this should have is on ground cooling, but I am planning on = exhaust=20 augmenters to assist cooling. 
 
 
I believe the=20 issue is the root area as you recalled.  The IVO is just a flat bar = at that=20 point, and creates a bunch of drag.  I believe Tracy wanted to = try it=20 again, but with some sort of cuffs added to the spinner to improve = the=20 shape.  FWIW, this problem also exists to some extent with = our monster=20 props, since the center is also pretty flat.  Tracy did in fact = make a=20 funky looking cuff that smoothes out the root area of his new prop, = and he=20 felt like it did make a measurable difference.  I haven't done it, = and I=20 don't think Ed has either.  
 
I had also=20 speculated previously that pushers wouldn't be effected as much, = because=20 the fuselage blocks much of the effected area.  Al will be=20 disappointed to hear that I have absolutely no engineering studies = to back=20 that up :-)  
 
Cheers,
Rusty (parts=20 needed) 
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