X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Tue, 21 Oct 2008 21:17:08 -0400 Message-ID: X-Original-Return-Path: Received: from smtp-ext-02.mx.pitdc1.expedient.net ([206.210.69.142] verified) by logan.com (CommuniGate Pro SMTP 5.2.9) with ESMTPS id 3232272 for lml@lancaironline.net; Tue, 21 Oct 2008 09:43:13 -0400 Received-SPF: none receiver=logan.com; client-ip=206.210.69.142; envelope-from=rpastusek@htii.com Received: from dlhtpax009 (static-71-178-198-10.washdc.fios.verizon.net [71.178.198.10]) by smtp-ext-02.mx.pitdc1.expedient.net (Postfix) with ESMTPA id 0A1AF7C7B2 for ; Tue, 21 Oct 2008 09:42:38 -0400 (EDT) Reply-To: From: "Robert Pastusek" X-Original-To: "'Lancair Mailing List'" References: In-Reply-To: Subject: RE: [LML] Yaw Damper in IVP X-Original-Date: Tue, 21 Oct 2008 09:42:34 -0400 Organization: Holmes-Tucker International, Inc. X-Original-Message-ID: <014b01c93382$dff54cd0$9fdfe670$@com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Mailer: Microsoft Office Outlook 12.0 Thread-Index: AckzOvGGfiNSOPEEQLao3Sj/+40ZNwARgLeg Content-Language: en-us John Barrett wrote: I'm interested to know about any experiences with Tru Trak and yaw damper in the IVP. Is there a need to add auto trim? I seem to recall reports that without the yaw damper the aircraft gets a little unstable longitudinally, but can the yaw damper solve the problem on its own? John, I have an IV-P with a TISO 550 Continental, winglets and a two-axis TruTrak SVGS autopilot that's fed from a Chelton Sport system. I have not found the yaw to be a problem at all, and deleted the TruTrak yaw damper from my original plan based on the recommendation of other builders. For my money, invest elsewhere in your toy... Ditto for the auto trim. My SVGS indicates when the aircraft is out of (pitch only) trim. This is easy to see and correct with a blip of the trim switch during a normal instrument scan. The trim changes very little in cruise flight; it's mainly a function of airspeed, so you'll need to monitor it a bit more closely during climbs, descents and power changes, but again for my money, invest elsewhere. Aileron and rudder trim on my airplane stay in the center with two exceptions: I use aileron trim to correct for fuel mis-management--more than a 10 gallon imbalance between the wings, and rudder trim to manage yaw during power changes. The rudder trim change required is significant between high power settings at low speed (climbs) and cruise. Not so significant for high speed descent when the power is reduced, but perhaps a blip or two. Last item: I spent some time and effort building a "dual speed" pitch trim system into my airplane. Had a minor wiring problem that kept it from working during the initial test flights, so I just disabled it. I like the trim system as it is now; wish I'd not wasted the time with the dual speed system... Bob PS: I understand that the turbine-powered airplane is significantly different, although this is second-hand to me. The above may not apply at all to the IV-PT airplanes.