X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 27 Feb 2012 10:03:35 -0500 Message-ID: X-Original-Return-Path: Received: from elasmtp-dupuy.atl.sa.earthlink.net ([209.86.89.62] verified) by logan.com (CommuniGate Pro SMTP 5.4.4) with ESMTP id 5416752 for lml@lancaironline.net; Sun, 26 Feb 2012 19:49:51 -0500 Received-SPF: none receiver=logan.com; client-ip=209.86.89.62; envelope-from=colyncase@earthlink.net DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; d=earthlink.net; b=bSc9QSQK+RAwjKZqT5FquB4dDXvIE6bgGnWvGst4psDCw8ONmegzPJzukqhegi62; h=Received:From:Mime-Version:Content-Type:Subject:Date:In-Reply-To:To:References:Message-Id:X-Mailer:X-ELNK-Trace:X-Originating-IP; Received: from [70.20.44.47] (helo=[192.168.1.24]) by elasmtp-dupuy.atl.sa.earthlink.net with esmtpa (Exim 4.67) (envelope-from ) id 1S1omD-00006a-B5 for lml@lancaironline.net; Sun, 26 Feb 2012 19:49:17 -0500 From: Colyn Case Mime-Version: 1.0 (Apple Message framework v1084) Content-Type: multipart/alternative; boundary=Apple-Mail-142--190761269 Subject: Re: [LML] Re: LNC4 AILERON TRIM TAB X-Original-Date: Sun, 26 Feb 2012 19:49:16 -0500 In-Reply-To: X-Original-To: "Lancair Mailing List" References: X-Original-Message-Id: X-Mailer: Apple Mail (2.1084) X-ELNK-Trace: 63d5d3452847f8b1d6dd28457998182d7e972de0d01da9407702c37c860fb011d32295ca9d89e8e6350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c X-Originating-IP: 70.20.44.47 --Apple-Mail-142--190761269 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=windows-1252 Another consideration is controllability at max trim travel. If I get to do it again I will reduce the travel or area on each trim = surface so that full deflection results in forces I can easily overcome = manually at the two speed extremes of the envelope. Yes there are = trim limiting control circuits.... Colyn On Feb 26, 2012, at 4:44 PM, Robert R Pastusek wrote: Carl Scheid wrote: At Oshkosh I was told that the aileron trim tab, shown in the = construction manual was inadaquate. Is that true? If so, what type of = trim tab is recommended for a non turbo LIV? =20 Carl, When building my IV-P, I cut out a section of the aileron and made this = into a trim tab, hinged at the bottom. As the effective moment was = shorter than the original metal tab, I made the tab 10=94 long and 1.5=94 = wide=97more than three times the surface area of the original tab, and = increased the deflection to +/- 25 degrees. =20 This has been sufficient in my 750 flight hours to date, but I use very = little aileron trim. In fact, if I see the aileron trim deflected more = than 5 degrees or so, I know it=92s time to switch fuel tanks. Most of = the time I fly on autopilot with the aileron trim neutral. The TruTrak = DGSV autopilot does an excellent job of keeping the airplane on a steady = and constant track. =20 The only time I=92ve felt a need for more trim was when I was doing fuel = system testing. I ran each wing tank empty one at a time, with 20-25 = gallons of fuel in the other tank. At cruise speed, the trim is more = than adequate to hold the wings level, but as I slowed the airplane = down, I had to run the trim all the way to the limit to do so. I did not = test this, but I suspect that with more than a 20-25 gallon fuel = imbalance, I=92d not have adequate roll trim. On the other hand, I = couldn=92t envision a situation that would get me in that position = during flight=85 =20 Last thought: The aileron and pitch trim are not balanced at all. That = is, during normal cruise, a quick click of the pitch trim will = noticeably change the stick force required to hold the pitch steady. The = aileron trim will require a couple of seconds of run time=85or more=85to = achieve a comparable roll force on the stick. One might think this = should be better balanced, but the reason it=92s done this way is that a = substantially larger pitch trim movement is required to maintain neutral = stick forces as the airplane is slowed down and configured for landing. = This also varies substantially with loading and CG location=85a couple = of heavy passengers in the back seat really change the pitch = characteristics of the airplane from 2-person, or single pilot = operation. =20 My advice=85increase the area of the aileron trim tab to double the = Lancair-provided tab. If you recess it in the aileron, make it about = three times the area of the original. Consider the position of the = existing ribs in the aileron and fit the tab between them. =20 Good luck; call me if questions. =20 Bob Pastusek 757-286-4802 --Apple-Mail-142--190761269 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=windows-1252

Carl Scheid wrote:

At Oshkosh I was told that the aileron trim = tab, shown in the construction manual was inadaquate. Is that true? If = so, what type of trim tab is recommended for a non turbo = LIV?
 
This has been sufficient in my = 750 flight hours to date, but I use very little aileron trim. In fact, = if I see the aileron trim deflected more than 5 degrees or so, I know = it=92s time to switch fuel tanks. Most of the time I fly on autopilot = with the aileron trim neutral. The TruTrak DGSV autopilot does an = excellent job of keeping the airplane on a steady and constant = track.
The only time I=92ve felt a need = for more trim was when I was doing fuel system testing. I ran each wing = tank empty one at a time, with 20-25 gallons of fuel in the other tank. = At cruise speed, the trim is more than adequate to hold the wings level, = but as I slowed the airplane down, I had to run the trim all the way to = the limit to do so. I did not test this, but I suspect that with more = than a 20-25 gallon fuel imbalance, I=92d not have adequate roll trim. = On the other hand, I couldn=92t envision a situation that would get me = in that position during flight=85
Last thought: The aileron and = pitch trim are not balanced at all. That is, during normal cruise, a = quick click of the pitch trim will noticeably change the stick force = required to hold the pitch steady. The aileron trim will require a = couple of seconds of run time=85or more=85to achieve a comparable roll = force on the stick. One might think this should be better balanced, but = the reason it=92s done this way is that a substantially larger pitch = trim movement is required to maintain neutral stick forces as the = airplane is slowed down and configured for landing. This also varies = substantially with loading and CG location=85a couple of heavy = passengers in the back seat really change the pitch characteristics of = the airplane from 2-person, or single pilot = operation.
My advice=85increase the area of = the aileron trim tab to double the Lancair-provided tab. If you recess = it in the aileron, make it about three times the area of the original. = Consider the position of the existing ribs in the aileron and fit the = tab between them.
Good luck; call me if = questions.
Bob = Pastusek