Return-Path: Received: from out012.verizon.net ([206.46.170.137] verified) by logan.com (CommuniGate Pro SMTP 4.2b3) with ESMTP id 85966 for flyrotary@lancaironline.net; Sun, 23 May 2004 14:30:25 -0400 Received: from verizon.net ([4.12.145.173]) by out012.verizon.net (InterMail vM.5.01.06.06 201-253-122-130-106-20030910) with ESMTP id <20040523183025.SZYA18295.out012.verizon.net@verizon.net> for ; Sun, 23 May 2004 13:30:25 -0500 Message-ID: <40B0EDB9.90606@verizon.net> Date: Sun, 23 May 2004 14:30:17 -0400 From: Finn Lassen User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.4) Gecko/20030624 Netscape/7.1 (ax; PROMO) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Rotary motors in aircraft Subject: Re: [FlyRotary] Trim Adjustment was Re: [FlyRotary] Re: engine mount geometry References: In-Reply-To: Content-Type: multipart/alternative; boundary="------------040105030101030407000106" X-Authentication-Info: Submitted using SMTP AUTH at out012.verizon.net from [4.12.145.173] at Sun, 23 May 2004 13:30:24 -0500 This is a multi-part message in MIME format. --------------040105030101030407000106 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Ed Anderson wrote: > 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. > > 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. > > 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. > > Years ago someone told me he was going to design his vert stab like an airfoil. The idea being that as the airspeed varied the "lift" of the vert stab would change. Finn --------------040105030101030407000106 Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: 7bit Ed Anderson wrote:

Message

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.

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.

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.

Years ago someone told me he was going to design his vert stab like an airfoil. The idea being that as the airspeed varied the "lift" of the vert stab would change.

Finn
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