X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: <13brv3@bellsouth.net> Received: from imf21aec.mail.bellsouth.net ([205.152.59.69] verified) by logan.com (CommuniGate Pro SMTP 5.0.3) with ESMTP id 872439 for flyrotary@lancaironline.net; Mon, 12 Dec 2005 11:24:55 -0500 Received-SPF: pass receiver=logan.com; client-ip=205.152.59.69; envelope-from=13brv3@bellsouth.net Received: from ibm63aec.bellsouth.net ([65.6.194.9]) by imf21aec.mail.bellsouth.net with ESMTP id <20051212162405.URZZ29696.imf21aec.mail.bellsouth.net@ibm63aec.bellsouth.net> for ; Mon, 12 Dec 2005 11:24:05 -0500 Received: from rd ([65.6.194.9]) by ibm63aec.bellsouth.net with ESMTP id <20051212162358.FGHM24930.ibm63aec.bellsouth.net@rd> for ; Mon, 12 Dec 2005 11:23:58 -0500 From: "Russell Duffy" <13brv3@bellsouth.net> To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: "P" factor? Re: Static Engine RPM Date: Mon, 12 Dec 2005 10:23:58 -0600 Message-ID: <000001c5ff38$748398c0$6101a8c0@rd> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0001_01C5FF06.29E928C0" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6626 Importance: Normal In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2527 This is a multi-part message in MIME format. ------=_NextPart_000_0001_01C5FF06.29E928C0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable I don't recall whether Tracy adjusted his motor mount for his 2.85 and larger prop or not.=20 =20 Tracy's RV-4 mount is straight, with no offset either direction. When I first put the 2.85 drive on the RV-3, while it still had the opposite = engine mount thrust angle, it was an evil uncontrollable beast. =20 =20 I made one (and only one) takeoff from the three point stance. If the = plane wasn't so overpowered, it would have been a ground loop for sure. = Despite full right rudder, the plane left the ground just as it departed the = left side of the runway. From that point on, I would ease into the power, = until I could get the plane going fast enough to raise the tail, then I could = roll on the rest of the throttle. On one hand, this would seem to show that = the primary problem was due to P factor, but on the other hand, the rudder = is also far more effective once you reach tail flying speed, so maybe = that's the simple reason it was more controllable. =20 =20 I was able to shim the mount back to zero offset, but that was as far as = I could reasonably go. Of course, when you shim the mount on an RV-3, = you're also turning the main gear as well. What I ended up with was the engine pointing forward, and the main gear pointing a couple degrees to the = right. Maybe that helped too. The difference was simply amazing, and the = plane is a pussy cat compared to having the wrong thrust. =20 Cheers, Rusty (Kolb now has more wires than any 3 other Kolbs combined) =20 ------=_NextPart_000_0001_01C5FF06.29E928C0 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Message
I don't recall whether Tracy adjusted his motor mount for his 2.85 = and=20 larger prop or not. 
 
Tracy's RV-4 = mount is=20 straight, with no offset either direction.  When I first put = the 2.85=20 drive on the RV-3, while it still had the opposite engine mount thrust = angle, it=20 was an evil uncontrollable beast.  
 
I made one = (and only=20 one) takeoff from the three point stance.  If the plane wasn't = so=20 overpowered, it would have been a ground loop for sure.  Despite = full right=20 rudder, the plane left the ground just as it departed the left side = of the=20 runway.  From that point on, I would ease into the = power, until I could get the = plane going=20 fast enough to raise the tail, then I could roll on the rest of the = throttle.  On one hand, this would seem to show that the = primary problem=20 was due to P factor, but on the other hand, the rudder is also far more=20 effective once you reach tail flying speed, so maybe that's the = simple=20 reason it was more controllable.  
 
I was able = to shim the=20 mount back to zero offset, but that was as far as I could reasonably = go. =20 Of course, when you shim the mount on an RV-3, you're also turning the = main gear=20 as well.  What I ended up with was the engine pointing forward, and = the=20 main gear pointing a couple degrees to the right.  Maybe that = helped=20 too.   The difference was = simply=20 amazing, and the plane is a pussy cat compared to having the wrong=20 thrust.
 
Cheers,
Rusty (Kolb = now has more=20 wires than any 3 other Kolbs=20 combined)  
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