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 rv-out-0506.google.com ([209.85.198.225] verified) by logan.com (CommuniGate Pro SMTP 5.2.13) with ESMTP id 3592777 for lml@lancaironline.net; Wed, 22 Apr 2009 09:52:35 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.198.225; envelope-from=vonjet@gmail.com Received: by rv-out-0506.google.com with SMTP id f9so2605689rvb.7 for ; Wed, 22 Apr 2009 06:51:58 -0700 (PDT) DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:from:to:in-reply-to:content-type:x-mailer:mime-version :subject:date:references; b=Z9UghotWoQNIQU4ippfD+4DA2dWLfqScosnFqgKHqv9Fc6WHAFHcTCVMVX2fTsfSMZ 7cXxTKn0ZBIWujOSjrCz+HLcv9xve8fRDBRtbQkoAUIQUK5GrL9u+oEO8TeF67VwrWSX 7zLKnQYUz5vF9AoAngsb1PJDA6Wsp3bQMQzCo= Received: by 10.114.76.8 with SMTP id y8mr4597821waa.201.1240408318379; Wed, 22 Apr 2009 06:51:58 -0700 (PDT) X-Original-Return-Path: Received: from ?192.168.2.5? (cpe-98-149-73-57.socal.res.rr.com [98.149.73.57]) by mx.google.com with ESMTPS id n30sm10863030wag.56.2009.04.22.06.51.56 (version=TLSv1/SSLv3 cipher=RC4-MD5); Wed, 22 Apr 2009 06:51:57 -0700 (PDT) X-Original-Message-Id: <48185A5B-C153-487C-9BB2-B3E9249FFD28@gmail.com> From: Bryan Wullner X-Original-To: Lancair Mailing List In-Reply-To: Content-Type: multipart/alternative; boundary=Apple-Mail-1-108061171 X-Mailer: iPod Mail (5H11) Mime-Version: 1.0 (iPod Mail 5H11) Subject: Re: [LML] Re: Balancing MkII Elevators X-Original-Date: Wed, 22 Apr 2009 06:51:05 -0700 References: --Apple-Mail-1-108061171 Content-Type: text/plain; charset=us-ascii; format=flowed; delsp=yes Content-Transfer-Encoding: 7bit Thanks Rob. Now I dont feel so bad. Bryan On Apr 22, 2009, at 6:26 AM, rwolf99@aol.com wrote: > 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! --Apple-Mail-1-108061171 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable

Thanks Rob. Now I dont feel so bad. = rwolf99@aol.com = wrote:

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!

= --Apple-Mail-1-108061171--