Return-Path: Received: from [24.25.9.101] (HELO ms-smtp-02-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 4.2b3) with ESMTP id 85817 for flyrotary@lancaironline.net; Sun, 23 May 2004 11:51:53 -0400 Received: from EDWARD (clt25-78-058.carolina.rr.com [24.25.78.58]) by ms-smtp-02-eri0.southeast.rr.com (8.12.10/8.12.7) with SMTP id i4NFpoNs026850 for ; Sun, 23 May 2004 11:51:51 -0400 (EDT) Message-ID: <000c01c440dd$e05abe90$2402a8c0@EDWARD> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Trim Adjustment was Re: [FlyRotary] Re: engine mount geometry Date: Sun, 23 May 2004 11:51:56 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0009_01C440BC.58F5CE70" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1409 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1409 X-Virus-Scanned: Symantec AntiVirus Scan Engine This is a multi-part message in MIME format. ------=_NextPart_000_0009_01C440BC.58F5CE70 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message=20 I would like to hear what you guys say about this geometry. does the = vert stab offset create drag? is one way better than another? will = higher cruise speeds affect the alignment, I know it affects rudder = trim? Kevin Lane Portland, OR=20 I'd like to know this as well. As far as I can tell, offsetting the = vert stab is no different than applying some rudder trim, which I can = certainly do. The real question for me is whether the engine offset is = any better than rudder trim, in terms of drag at cruise speed. =20 Cheers, Rusty (making the TB flange, and fitting the tubes later this = afternoon) =20 I think this gets to be a bit of a complex aerodynamic Question. = Rudder or any trim offers some drag, however if it aligns the body of = the aircraft more with the airstream, there could be an overall = reduction in drag. I would hesitate to offset the vertical stab. = Here's my reason.=20 1. Any fixed trim is generally only good for one airspeed and power = setting, so unless you never intend or think your gear box, prop or = engine is going to change I wouldn't try to compensate with vertical = stab. Once it set, it a lot of work to change.=20 2. Cockpit trim is of course the ideal, but then you may have to = rig up something to drive the trim tab, worry about what that might do = to flutter points, etc. this one takes time, money and effort to get it = right. 3. An adjustable trim (such as a rudder trim tab) can be adjusted to = take care of such changes as mentioned in 1 above All in all, its hard to beat a trim tab for adjustability, weight, = cost, and ease of application and since a vertical stab orientation or a = trim tab are both only idea for one airspeed and the tab is much easier = to adjust - I would vote for it. Just my 0.02 worth Ed Anderson ------=_NextPart_000_0009_01C440BC.58F5CE70 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message
 
 I would like to hear what you guys say about this = geometry.  does=20 the vert stab offset create drag?  is one way better than = another? =20 will higher cruise speeds affect the alignment, I know it affects = rudder=20 trim?
Kevin Lane  Portland, OR 
 
I'd like=20 to know this as well.  As far as I can tell, offsetting the = vert=20 stab is no different than applying some rudder trim, which I can=20 certainly do.  The real question for me is whether = the engine offset=20 is any better than rudder trim, in terms of drag at cruise=20 speed.  
 
Cheers,
Rusty=20 (making the TB flange, and fitting the tubes later this=20 afternoon)   
I think this gets to be a bit of a = complex=20 aerodynamic Question.  Rudder or any trim offers some drag, = however if it=20 aligns the body of the aircraft more with the airstream, there could = be an=20 overall reduction in drag.  I would hesitate to offset the = vertical=20 stab.  Here's my reason.
 
1. Any fixed trim is generally only = good for one=20 airspeed and power setting, so unless you never intend or think your = gear box,=20 prop or engine is going to change I wouldn't try to compensate with = vertical=20 stab.  Once it set, it a lot of work to change.
 
2.  Cockpit   trim is = of course=20 the ideal, but then you may have to rig up something to drive the trim = tab,=20 worry about what that might do to flutter points, etc. this one takes = time,=20 money and effort to get it right.
 
3.  An adjustable trim (such as = a rudder=20 trim tab) can be adjusted to take care of such changes as mentioned in = 1=20 above
 
All in all, its hard to beat a trim = tab for=20 adjustability, weight, cost, and ease of application and since a = vertical stab=20 orientation or a trim tab are both only idea for one airspeed and the = tab is=20 much easier to adjust - I would vote for it.
 
 
Just my 0.02 worth
 
Ed = Anderson
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