X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml Date: Fri, 04 Dec 2009 16:28:30 -0500 Message-ID: X-Original-Return-Path: Received: from s466.sureserver.com ([64.14.78.39] verified) by logan.com (CommuniGate Pro SMTP 5.3c3) with ESMTPS id 4002868 for lml@lancaironline.net; Fri, 04 Dec 2009 15:09:58 -0500 Received-SPF: none receiver=logan.com; client-ip=64.14.78.39; envelope-from=dskeele@Wvsf.org Received: (qmail 16008 invoked by uid 1003); 4 Dec 2009 20:09:20 -0000 Received: from unknown (HELO ownerPC) (12.161.184.226) by s466.sureserver.com with SMTP; 4 Dec 2009 20:09:20 -0000 X-Original-Message-ID: <73AD5453B81D45F9815E33696CB5A64D@ownerPC> From: "Don Skeele" X-Original-To: "Lancair Mailing List" X-Original-Cc: References: In-Reply-To: Subject: Re: [LML] Control balance and flutter X-Original-Date: Fri, 4 Dec 2009 14:08:43 -0600 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0096_01CA74EB.49949010" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Windows Mail 6.0.6001.18000 X-MimeOLE: Produced By Microsoft MimeOLE V6.0.6001.18049 This is a multi-part message in MIME format. ------=_NextPart_000_0096_01CA74EB.49949010 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Justin, Appreciate your thread on Control Surface and Flutter. I flew 235/320 = Lancair N320J for about 900 hrs and in that time I experienced a couple = of "flutter events" .. One, at about 400 hrs started with a "buzz" when = reflexing the flaps when establishing cruise speed and configuration at = 6 to 10 thousand feet range and 185 kts indicated. I could make it come = and go depending upon moving the flap position to the fully relexed = position of about 5/8" up, reflex. Replaced the outboard left elevator = hinge which had some 1/16" play (about).. Buzz went away at all speeds = etc. Our thoughts at the time, and old A&I and me, was that there was = inter reaction between the air flow past the flap and that particular = side of the horiz stabilizer/elevator had set it up, at that specific = set of conditions,since the flaps were tight. I have no more data to = describe,other than that the elevator hinge replacement fixed the = problem. =20 The second occurred at about 750 Hrs airframe. N320J had a vertical = strake starting just behind the wing TE and ending at 7" vertical at the = larger tail. It had a foam core with 2 bids of light cloth over a = Sterling Polyurethane paint job. The 18 year old paint job showed a = vertical crack on either side of, only the strake, located below the LE = of the horiz stabilizer. After sanding off the cracked paint area, there = was no apparent damage to the strake itself. Did a 2 bid light cloth = across the area a foot or so either side and repainted. The forces that = cracked the quite brittle paint appeared tobe a sideways deflection of = the entire tail section. Russ Connel suggested that installing a = bulkhead at this point would help. This all occurred just below the = smallest cross-section of the fuselage. Might be something other = builders might want to consider, especially with the larger tail. She = was a great machine and a delight to fly.. Regards ------=_NextPart_000_0096_01CA74EB.49949010 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Justin,
Appreciate your thread on Control = Surface and=20 Flutter. I flew 235/320 Lancair N320J for about 900 hrs and in that time = I=20 experienced a couple of "flutter events" .. One, at about 400 hrs = started=20 with a "buzz" when reflexing the flaps when establishing cruise speed = and=20 configuration  at 6 to 10 thousand feet range and 185 = kts indicated. I=20 could make it come and go depending upon moving the flap=20 position to the fully relexed position of about 5/8" up,=20 reflex.  Replaced the outboard left elevator hinge which had=20 some 1/16" play (about).. Buzz went away at all speeds etc. =  Our=20 thoughts at the time, and old A&I and me, was that there was inter=20 reaction between the air flow past the flap and = that particular side=20 of the horiz stabilizer/elevator had set it up, at that specific = set of=20 conditions,since the flaps were tight.  I have no more data to = describe,other than that the elevator hinge replacement fixed the=20 problem.  
  The second occurred at about 750 = Hrs=20 airframe.  N320J had a vertical strake starting just behind = the wing=20 TE and ending at 7" vertical at the larger tail.  It had = a foam=20 core with 2 bids of light cloth over a Sterling Polyurethane paint=20 job.  The 18 year old paint job showed a vertical crack=20 on either side of, only the strake, located below the LE of = the horiz=20 stabilizer. After sanding off the cracked paint area, there was no = apparent=20 damage to the strake itself.  Did a 2 bid light cloth across = the area=20 a foot or so either side and repainted.  The forces that cracked=20 the quite brittle paint appeared tobe a sideways deflection of = the=20 entire tail section.  Russ Connel suggested that installing a = bulkhead at=20 this point would help.  This all occurred just below the smallest=20 cross-section of the fuselage.  Might be something other builders = might=20 want to consider, especially with the larger tail.  She was a = great=20 machine and a delight to fly..  Regards
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