X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Tue, 13 Nov 2007 17:02:56 -0500 Message-ID: X-Original-Return-Path: Received: from smtp121.sbc.mail.sp1.yahoo.com ([69.147.64.94] verified) by logan.com (CommuniGate Pro SMTP 5.2c2) with SMTP id 2470551 for lml@lancaironline.net; Tue, 13 Nov 2007 16:35:27 -0500 Received-SPF: none receiver=logan.com; client-ip=69.147.64.94; envelope-from=elippse@sbcglobal.net Received: (qmail 74196 invoked from network); 13 Nov 2007 21:34:49 -0000 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=sbcglobal.net; h=Received:X-YMail-OSG:Message-ID:From:To:Subject:Date:MIME-Version:Content-Type:X-Priority:X-MSMail-Priority:X-Mailer:X-MimeOLE; b=bxPQ2dd8in74iecdwRXeshPJwx8rD17yqMHUR3+7AYRaxxVYTYLQ83f4hbqMRFf9GNMJ9VKkQZrNQMKXILkeWtVAsV4FBFnqBS3uIHWy/BcVd88IYpxTOozDfXY9Hvuw82p7l6PyicCzlpEDJoyujB0DrCRUgFC+X/VUqgG4OQM= ; Received: from unknown (HELO Computerroom) (elippse@sbcglobal.net@75.15.146.148 with login) by smtp121.sbc.mail.sp1.yahoo.com with SMTP; 13 Nov 2007 21:34:49 -0000 X-YMail-OSG: v6lvu.4VM1nt1GeLDjqNJ6KFuxRbTF6MU1vnOhvZh8Qbp8uytc8r7JeDkOVB7fI5bqyC3e7w0A-- X-Original-Message-ID: <000801c8263d$0ba7b560$94920f4b@Computerroom> From: "Paul Lipps" X-Original-To: "Marv Kaye" Subject: Aileron trim X-Original-Date: Tue, 13 Nov 2007 13:34:58 -0800 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0005_01C825F9.FC42A690" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3138 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3198 This is a multi-part message in MIME format. ------=_NextPart_000_0005_01C825F9.FC42A690 Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable My friend's L235/320 had a Mac servo in the left aileron with a = small tab just in back of the aileron trailing edge. What I found most = troublesome about this method of trim is that it is totally dependent on = airspeed to accomplish the trim force. By that I mean that if you have a = slight lateral unbalance from fuel, passenger, or baggage, the amount of = trim tab deflection must change when you change speed. So if you have an = unbalance, and are in trim during cruise, as you slow for approach and = landing you will continuously have to increase the tab deflection. I = decided to get rid of this feature in the plane I was building, so I = incorporated a trim based on applying a constant trim force to the = ailerons which caused the aileron deflection to change with speed to = always match the aero force on the aileron from dynamic pressure. To = this end I made a trim system consisting of a phenolic drum in the = console with 1/16" cable wrapped twice around it which went down and = then out to a spring on each side attached to the bottom of the control = stick. The springs I used are the over-center springs from the L235 = main-gear, which has a spring- rate of 5lb./in.; this gave a combined = force of 10 lb./in. for the two. A pre-tension force of about 10 lb. was = included in the springs when attached. This drum in the console was = driven through a knob which turned the drum through 4:1 gears. It's an = absolute joy to set it and forget it. By the opposite token, I installed a mechanically-driven trim tab in = my elevator in place of the spring-driven force on the elevator = push-pull tube, since speed-variation of trim is a desired feature of = elevator trim since it tends to maintain a constant speed, whereas the = spring trim maintains a constant force. As CG changes with fuel = depletion, it is necessary to change the trim force. This is almost = automatic with the elevator trim tab. I drove the tab through = nylon-lined bicycle brake conduit with solid wire instead of the = stranded. Much, much lighter and more flexible than Bowden cable. = Additionally, I have attached a spring from the flap-actuating arm to = the elevator push-pull tube in the center console. This spring gives an = up-elevator drive as the flaps are lowered to help, almost completly, to = maintain speed trim during landing. ------=_NextPart_000_0005_01C825F9.FC42A690 Content-Type: text/html; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable
    My friend's L235/320 had a = Mac servo in=20 the left aileron with a small tab just in back of the aileron trailing = edge.=20 What I found most troublesome about this method of trim is that it is = totally=20 dependent on airspeed to accomplish the trim force. By that I mean that = if you=20 have a slight lateral unbalance from fuel, passenger, or baggage, the = amount of=20 trim tab deflection must change when you change speed. So if you have an = unbalance, and are in trim during cruise, as you slow for approach = and=20 landing you will continuously have to increase the tab deflection. I = decided to=20 get rid of this feature in the plane I was building, so I = incorporated a=20 trim based on applying a constant trim force to the = ailerons which=20 caused the aileron deflection to change with speed to always match the = aero=20 force on the aileron from dynamic pressure. To this end I made a trim = system=20 consisting of a phenolic drum in the console with 1/16" cable = wrapped=20 twice around it which went down and then out to a spring on = each side=20 attached to the bottom of the control stick. The springs I used are the=20 over-center springs from the L235 main-gear, which has a spring- rate of = 5lb./in.; this gave a combined force of 10 lb./in. for the two. A = pre-tension=20 force of about 10 lb. was included in the springs when attached. This = drum in=20 the console was driven through a knob which turned the drum through 4:1 = gears.=20 It's an absolute joy to set it and forget it.
    By the opposite token, I = installed a=20 mechanically-driven trim tab in my elevator in place of the = spring-driven force=20 on the elevator push-pull tube, since speed-variation of trim is a = desired=20 feature of elevator trim since it tends to maintain a constant speed, = whereas=20 the spring trim maintains a constant force. As CG changes with fuel = depletion,=20 it is necessary to change the trim force. This is almost automatic = with the=20 elevator trim tab. I drove the tab through nylon-lined bicycle brake = conduit=20 with solid wire instead of the stranded. Much, much lighter and more=20 flexible than Bowden cable. Additionally, I have attached a spring = from the=20 flap-actuating arm to the elevator push-pull tube in the center console. = This=20 spring gives an up-elevator drive as the flaps are lowered to help, = almost=20 completly, to maintain speed trim during = landing.
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