X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from [24.25.9.103] (HELO ms-smtp-04-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 5.0.3) with ESMTP id 873185 for flyrotary@lancaironline.net; Mon, 12 Dec 2005 21:24:37 -0500 Received-SPF: pass receiver=logan.com; client-ip=24.25.9.103; envelope-from=eanderson@carolina.rr.com Received: from edward2 (cpe-024-074-025-165.carolina.res.rr.com [24.74.25.165]) by ms-smtp-04-eri0.southeast.rr.com (8.12.10/8.12.7) with SMTP id jBD2No1u013778 for ; Mon, 12 Dec 2005 21:23:50 -0500 (EST) Message-ID: <001701c5ff8c$42609f60$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: "P" factor? Re: Static Engine RPM Date: Mon, 12 Dec 2005 21:23:52 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0014_01C5FF62.595619E0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2180 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 X-Virus-Scanned: Symantec AntiVirus Scan Engine This is a multi-part message in MIME format. ------=_NextPart_000_0014_01C5FF62.595619E0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Bob, if there is any pull to the right then its more than offset by the = yaw to the left caused by (take your pick) 1. Torque 2. "P" Factor 3. = Air Swirl {:>). It may be that the small difference in an already = fairly light prop does not have a lot of impact. On the other hand = there may a Lot of gyroscopic precession when I rotate and that is what = keeps me on the runway heading (more or less){:>) Ed ----- Original Message -----=20 From: Bob Perkinson=20 To: Rotary motors in aircraft=20 Sent: Monday, December 12, 2005 11:42 AM Subject: [FlyRotary] Re: "P" factor? Re: Static Engine RPM Ed, Not being the number crunching type, where does Gyroscopic Precession = come in to play? With the larger prop, do you notice any effect when = the nose is rotated up? The way I picture it, there should be some = momentary pull to the right. Bob Perkinson Hendersonville, TN. RV9 N658RP Reserved If nothing changes Nothing changes =20 No familiar with the SA-16, Bob, but are both props turning same = direction or opposite - would make a significant difference in whether = there is a swirl (my spell checker says OK {:>)) effect or not. If in = opposite directions then I would agree, if both props rotating in same = direction then harder to say. For a long time I thought that Torque was the major cause, however, = I remain convinced (at this point) that the low rolling and large yaw = force is primarily caused by swirl. Having encountered prop swirl on = take off roll too close behind Finn's RV3 there is no question in my = mind that prop swirl is a powerful force. But, regardless whether = torque or swirl (or combination), the 2.85 gear box and larger prop = makes a considerable change. =20 I don't recall whether Tracy adjusted his motor mount for his 2.85 = and larger prop or not. Ed A ------=_NextPart_000_0014_01C5FF62.595619E0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Bob, if there is any pull to the right then its more than offset by = the yaw=20 to the left caused by (take your pick) 1. Torque 2. "P" Factor 3. Air = Swirl=20 {:>).  It may be that the small difference in an already fairly = light=20 prop does not have a lot of impact.  On the other hand there may a = Lot of=20 gyroscopic precession when I rotate and that is what keeps me on the = runway=20 heading (more or less){:>)
 
Ed
----- Original Message -----
From:=20 Bob=20 Perkinson
Sent: Monday, December 12, 2005 = 11:42=20 AM
Subject: [FlyRotary] Re: "P" = factor? Re:=20 Static Engine RPM

Ed,
Not being the number crunching = type, where=20 does Gyroscopic Precession come in to play?  With the larger = prop, do you=20 notice any effect when the nose is rotated up?  The way I picture = it,=20 there should be some momentary pull to the right.

Bob Perkinson
Hendersonville, TN.
RV9 N658RP=20 Reserved
If nothing changes
Nothing = changes
 

 
No familiar with the SA-16, Bob, but are both props turning = same=20 direction or opposite - would make a significant difference in = whether there=20 is a swirl (my spell checker says OK {:>)) effect or not.  = If in=20 opposite directions then I would agree, if both props rotating in = same=20 direction then harder to say.
 
For a long time I thought that Torque was the major cause, = however, I=20 remain convinced (at this point) that the low rolling and large yaw = force is=20 primarily caused by swirl. Having encountered prop swirl on take off = roll=20 too close behind Finn's RV3 there is no question in my mind that = prop swirl=20 is a powerful force.   But, regardless whether torque or = swirl (or=20 combination), the 2.85 gear box and larger prop makes a considerable = change. 
 
I don't recall whether Tracy adjusted his motor mount for his = 2.85 and=20 larger prop or not.
 
Ed A
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