X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Thu, 23 Apr 2009 20:40:50 -0400 Message-ID: X-Original-Return-Path: Received: from fmailhost03.isp.att.net ([204.127.217.103] verified) by logan.com (CommuniGate Pro SMTP 5.2.13) with ESMTP id 3592820 for lml@lancaironline.net; Wed, 22 Apr 2009 10:57:58 -0400 Received-SPF: pass receiver=logan.com; client-ip=204.127.217.103; envelope-from=bbradburry@bellsouth.net Received: from desktop (adsl-146-126-211.mco.bellsouth.net[72.146.126.211]) by isp.att.net (frfwmhc03) with SMTP id <20090422145720H0300nllc3e>; Wed, 22 Apr 2009 14:57:20 +0000 X-Originating-IP: [72.146.126.211] From: "Bill Bradburry" X-Original-To: "'Lancair Mailing List'" References: In-Reply-To: Subject: RE: [LML] Re: Balancing MkII Elevators X-Original-Date: Wed, 22 Apr 2009 10:57:29 -0400 X-Original-Message-ID: <860EFDB04F19444592385C46034F439D@Desktop> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0015_01C9C339.220FE8F0" X-Mailer: Microsoft Office Outlook 11 Thread-Index: AcnDTjfu9W+XPyhgQkeWk68y0L1/swADAZ3A X-MimeOLE: Produced By Microsoft MimeOLE V6.0.6001.18049 This is a multi-part message in MIME format. ------=_NextPart_000_0015_01C9C339.220FE8F0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit How do you determine that the control surface is balanced? Should the surface stay where you left it, or should it move from where ever you put it to a level position? Bill B _____ From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of rwolf99@aol.com Sent: Wednesday, April 22, 2009 9:27 AM To: lml@lancaironline.net Subject: [LML] Re: Balancing MkII Elevators I, too, was surprised at how much lead I needed to balance my 360 ailerons. In fact, I have those lead half-rounds going nearly full-span (two of them, flat surface to flat surface). But let's stop to think about it. We need as much "moment" (mass x distance) in front of the hinge line as behind it. In practice, we have more weight (balance weight) forward of the hinge line than we do behind it (the control surface itself) since the CG of the control surface is generally much further behind the hinge line than the balance weights are forward of it. This is certainly the case with the ailerons, but less so for the rudder and elevators, since they have those forward overhangs for aerodynamic balance. For preliminary design purposes, my airplane design group assumes that the balance weights weigh 1.5 times the weight of the control surface alone. Bottom line -- your balance weights need to be at least as heavy as the control surface, and up to 50% more. Yup, it's a lot. - Rob Wolf _____ The Average US Credit Score is 692. See Yours in Just 2 Easy Steps! ------=_NextPart_000_0015_01C9C339.220FE8F0 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

How do you determine that the control surface is balanced?  = Should the surface stay where you left it, or should it move from where ever = you put it to a level position?

 

Bill B 

 

From: Lancair Mailing List = [mailto:lml@lancaironline.net] On Behalf Of rwolf99@aol.com
Sent: Wednesday, April = 22, 2009 9:27 AM
To: = lml@lancaironline.net
Subject: [LML] Re: = Balancing MkII Elevators

I, too, was surprised at how much lead I needed to balance my = 360 ailerons.  In fact, I have those lead half-rounds going nearly = full-span (two of them, flat surface to flat surface).  But let's stop to = think about it.  We need as much "moment" (mass x = distance) in front of the hinge line as behind it.  In practice, we have more = weight (balance weight) forward of the hinge line than we do behind it (the = control surface itself) since the CG of the control surface is generally much = further behind the hinge line than the balance weights are forward of it.  = This is certainly the case with the ailerons, but less so for the rudder and = elevators, since they have those forward overhangs for aerodynamic balance.

For preliminary design purposes, my airplane design group assumes that = the balance weights weigh 1.5 times the weight of the control surface = alone.

Bottom line -- your balance weights need to be at least as heavy as the = control surface, and up to 50% more.

Yup, it's a lot.

- Rob Wolf

 

=

The Average US Credit Score is 692. See Yours in Just 2 Easy Steps!

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