X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Thu, 30 Apr 2009 02:50:30 -0400 Message-ID: X-Original-Return-Path: Received: from elasmtp-curtail.atl.sa.earthlink.net ([209.86.89.64] verified) by logan.com (CommuniGate Pro SMTP 5.2.14) with ESMTP id 3611279 for lml@lancaironline.net; Wed, 29 Apr 2009 22:02:55 -0400 Received-SPF: none receiver=logan.com; client-ip=209.86.89.64; envelope-from=rtitsworth@mindspring.com DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; d=mindspring.com; b=stybTw7iEhusJh6pvAa7cs7lNff3RcieM0BVrnOjWiKHyVzMZV9MIs7gxMUax76d; h=Received:From:To:References:Subject:Date:Message-ID:MIME-Version:Content-Type:X-Mailer:X-MimeOLE:In-Reply-To:thread-index:X-ELNK-Trace:X-Originating-IP; Received: from [71.238.59.21] (helo=burtektp20) by elasmtp-curtail.atl.sa.earthlink.net with esmtpa (Exim 4.67) (envelope-from ) id 1LzLbR-0006lB-2n for lml@lancaironline.net; Wed, 29 Apr 2009 22:02:21 -0400 From: "Rick Titsworth" X-Original-To: "'Lancair Mailing List'" References: Subject: RE: [LML] Tungsten and other heavy metals X-Original-Date: Wed, 29 Apr 2009 22:02:19 -0400 X-Original-Message-ID: <7B2DC41A06A74114A333EEBD2D723D83@Burtekinc.local> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_016F_01C9C916.2ADCB2A0" X-Mailer: Microsoft Office Outlook 11 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 In-Reply-To: thread-index: AcnI1a1ts8nxQqMRRFu2yzGIkDhKMAAYePcg X-ELNK-Trace: b17f11247b2ac8f0a79dc4b33984cbaa0a9da525759e26544c6f6e2193e49bd40a3bd17f0349b483bd9aa8b00e01cd47350badd9bab72f9c350badd9bab72f9c X-Originating-IP: 71.238.59.21 This is a multi-part message in MIME format. ------=_NextPart_000_016F_01C9C916.2ADCB2A0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Why not cast/mold lead with tungsten rods imbedded? _____ From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of Gary Casey Sent: Wednesday, April 29, 2009 10:21 AM To: lml@lancaironline.net Subject: [LML] Tungsten and other heavy metals There was some discussion on the use of tungsten as a balance weight, so I did some research on the density of various materials - here is a list of approximate specific gravities: Typical epoxy resin - 1.5 Aluminum - 2.6 Steel - 7.8 Lead - 11.3 tungsten - 19.2 It would appear that the higher density of tungsten would allow a more compact balance weight, allowing the weight to be more concentrated to the extremity of the available space, reducing the overall weight. But things are not usually as simple as they at first seem. In order for lead to be effectively used it has to be cast in a shape to fit the space, which is what I did. It is hard to get all the air bubbles out, but a lead casting can be reasonably dense. The tungsten, however must be used in the form of powder or rods held together by an epoxy matrix. I don't have directly-related experience, but I would guess that it would be very difficult to get a 90% by volume tungsten mixture in epoxy (resulting specific gravity = 17.4) and if one was a little too casual and wanted to get an easily pourable mixture he could end up with a 50% mixture (specific gravity = 10.4), less dense than a lead casting. With reasonable care, which means careful measuring of the epoxy and thoroughly mixing without trapping too much air I would guess a 70% mix is reasonable and 80% is possible, but not likely. In comparison, rods perfectly nested in a linear pattern, not hexagonal, will be 78% "packed." A 70% mix will yield a specific gravity of 13.9, 23% greater than lead. Will that reduce the overall balancing weight by 23%? No, because only part of that weight is at a small radius - the weight savings is more likely to be about 10% or less. Is it worth the trouble? It might be if an accurate lead casting is particularly difficult, but otherwise I doubt it - at least that was the reasoning when I decided to use lead. Gary Casey ------=_NextPart_000_016F_01C9C916.2ADCB2A0 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable

Why not cast/mold lead with = tungsten rods imbedded?

 

From: = Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of Gary Casey
Sent: Wednesday, April = 29, 2009 10:21 AM
To: = lml@lancaironline.net
Subject: [LML] Tungsten = and other heavy metals

 

There was some discussion on the use of tungsten as a balance = weight, so I did some research on the density of various materials - here is a = list of approximate specific gravities:

Typical epoxy resin - 1.5

Aluminum - 2.6

Steel - 7.8

Lead - 11.3

tungsten - 19.2

 

It would appear that the higher density of tungsten would allow = a more compact balance weight, allowing the weight to be more concentrated to = the extremity of the available space, reducing the overall weight.  But = things are not usually as simple as they at first seem.  In order for lead = to be effectively used it has to be cast in a shape to fit the space, which is = what I did.  It is hard to get all the air bubbles out, but a lead casting = can be reasonably dense.  The tungsten, however must be used in the form = of powder or rods held together by an epoxy matrix.  I don't have directly-related experience, but I would guess that it would be very = difficult to get a 90% by volume tungsten mixture in epoxy (resulting specific = gravity =3D 17.4) and if one was a little too casual and wanted to get an easily = pourable mixture he could end up with a 50% mixture (specific gravity =3D 10.4), = less dense than a lead casting.  With reasonable care, which means = careful measuring of the epoxy and thoroughly mixing without trapping too much = air I would guess a 70% mix is reasonable and 80% is possible, but not likely.  In comparison, rods perfectly nested in a linear pattern, not = hexagonal, will be 78% "packed."  A 70% mix will yield a specific = gravity of 13.9, 23% greater than lead.  Will that reduce the overall = balancing weight by 23%?  No, because only part of that weight is at a small = radius - the weight savings is more likely to be about 10% or less.  Is it = worth the trouble?  It might be if an accurate lead casting is = particularly difficult, but otherwise I doubt it - at least that was the reasoning = when I decided to use lead.

 

Gary Casey

 

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