Return-Path: <13brv3@bellsouth.net> Received: from imf20aec.mail.bellsouth.net ([205.152.59.68] verified) by logan.com (CommuniGate Pro SMTP 4.2b3) with ESMTP id 84923 for flyrotary@lancaironline.net; Sat, 22 May 2004 19:28:41 -0400 Received: from rad ([65.6.194.9]) by imf20aec.mail.bellsouth.net (InterMail vM.5.01.06.08 201-253-122-130-108-20031117) with ESMTP id <20040522232840.XVFY1705.imf20aec.mail.bellsouth.net@rad> for ; Sat, 22 May 2004 19:28:40 -0400 From: "Russell Duffy" <13brv3@bellsouth.net> To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] engine mount geometry Date: Sat, 22 May 2004 18:26:38 -0500 Message-ID: <011c01c44054$3b336130$6001a8c0@rad> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_011D_01C4402A.525D5930" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.4510 Importance: Normal In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1165 This is a multi-part message in MIME format. ------=_NextPart_000_011D_01C4402A.525D5930 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable I am fabricating the bed mount plate for my 20B in an rv-8. my understanding, from Tracy's advice, is to offset the engine about 1 1/2 degrees to the right if I use his 2.85 drive.=20 =20 Hi Kevin, =20 Sorry I didn't think of this before, but last weekend, I measured the = offset of my friends RV-8 prop, but never did the math to see what it came out = to be. Basically, I put the prop horizontal, and measured from the tail, = to each tip. The difference was 2 inches, on a 74" prop, which works out = to 1.55 degrees right offset. =20 =20 The reason I measured this was to see what his offset was, because he = says he doesn't need any rudder in cruise. My RV-8 also required no rudder = in cruise, and neither of out planes had any offset in the vert stab. Curiously, the same measurement shows that my RV-3 (-B drive) has 1.25 degrees of left offset, and I need a buttload of left rudder in cruise. = The only thing I can concluded is that there is right offset somewhere in = the in the tail. I can't tell if the vert stab is offset, but it might be. = There could also just be something crooked that I can't spot. I didn't build = the tail, and fuselage, or I'd know if offset was put in. =20 =20 Since I'm going to the -C drive later this Summer, I'm more than a = little interested to see how the offset works out. Since there already seems = to be some other right offset force at work, I'll probably try flying the -C = drive with the left offset still in the mount. If I'm careful, it shouldn't = be dangerous, and then I can decide if I need to remove the current offset. = If I have to remove it, I'll shim the mount a half inch on the left to do = it. I'll also reposition the cowl to keep everything lined up. The prop = won't quite be centered, but I defy anyone to notice. =20 =20 Cheers, Rusty =20 ------=_NextPart_000_011D_01C4402A.525D5930 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Message

I am fabricating the bed mount plate for my 20B in an=20 rv-8.  my understanding, from Tracy's advice, is to offset the = engine about=20 1 1/2 degrees to the right if I use his 2.85 drive. 

 
Hi=20 Kevin,
 
Sorry I = didn't think of=20 this before, but last weekend, I measured the offset of my friends RV-8 = prop,=20 but never did the math to see what it came out to be.  Basically, I = put the=20 prop horizontal, and measured from the tail, to each tip.  The = difference=20 was 2 inches, on a 74" prop, which works out to 1.55 degrees right = offset. =20
 
The = reason I measured=20 this was to see what his offset was, because he says he doesn't need any = rudder=20 in cruise.  My RV-8 also required no rudder in cruise, and neither = of out=20 planes had any offset in the vert stab.  Curiously, the same = measurement=20 shows that my RV-3 (-B drive) has 1.25 degrees of left offset, and I = need a=20 buttload of left rudder in cruise.  The only thing I can concluded = is that=20 there is right offset somewhere in the in the tail.  I can't = tell if=20 the vert stab is offset, but it might be.  There could also just be = something crooked that I can't spot.  I didn't build = the tail,=20 and fuselage, or I'd know if offset was put = in.  
 
Since = I'm going to=20 the -C drive later this Summer, I'm more than a little interested to see = how the=20 offset works out.  Since there already seems to be some other = right=20 offset force at work, I'll probably try flying the -C drive with = the left=20 offset still in the mount.  If I'm careful, it shouldn't be = dangerous, and=20 then I can decide if I need to remove the current=20 offset.  If I have to remove it, I'll shim the mount a half = inch on=20 the left to do it.  I'll also reposition the cowl to keep = everything lined=20 up.  The prop won't quite be centered, but I defy anyone to=20 notice.  
 
Cheers,
Rusty
 



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