X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from imf16aec.mail.bellsouth.net ([205.152.59.64] verified) by logan.com (CommuniGate Pro SMTP 5.0.3) with ESMTP id 873161 for flyrotary@lancaironline.net; Mon, 12 Dec 2005 20:52:51 -0500 Received-SPF: pass receiver=logan.com; client-ip=205.152.59.64; envelope-from=bobperk@bellsouth.net Received: from ibm58aec.bellsouth.net ([65.1.103.202]) by imf16aec.mail.bellsouth.net with ESMTP id <20051212164453.XLKY9291.imf16aec.mail.bellsouth.net@ibm58aec.bellsouth.net> for ; Mon, 12 Dec 2005 11:44:53 -0500 Received: from HpPavilion310n ([65.1.103.202]) by ibm58aec.bellsouth.net with ESMTP id <20051212164453.NCWE21825.ibm58aec.bellsouth.net@HpPavilion310n> for ; Mon, 12 Dec 2005 11:44:53 -0500 From: "Bob Perkinson" To: "Rotary motors in aircraft" Subject: RE: [FlyRotary] Re: "P" factor? Re: Static Engine RPM Date: Mon, 12 Dec 2005 10:42:46 -0600 Message-ID: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_008D_01C5FF08.CB057180" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook IMO, Build 9.0.2416 (9.0.2910.0) In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 Importance: Normal This is a multi-part message in MIME format. ------=_NextPart_000_008D_01C5FF08.CB057180 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit 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 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. I don't recall whether Tracy adjusted his motor mount for his 2.85 and larger prop or not. Ed A ------=_NextPart_000_008D_01C5FF08.CB057180 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
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, there=20 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 = 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 too=20 close behind Finn's RV3 there is no question in my mind that prop = swirl is a=20 powerful force.   But, regardless whether torque or swirl = (or=20 combination), the 2.85 gear box and larger prop makes a considerable=20 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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