REFLECTOR: Reflector Digest, Vol 102, Issue 7

[Dave T Nelson]

While I am loathe to contradict Scott, I will say this...

Burt Rutan extensively studied the characteristics of the epoxies he
recommended for the Varieze and Longeze.  This study included testing for
compatibility of materials, structural strength at different temperatures,
and a whole load of other potential issues.  He only recommended SafetyPoxy
(and the follow on EZ-Poxy, which is the same formulation) after he
carefully ensured via extensive study and test that it would work.  He
never recommended West for anything other than non-structure applications
(like micro).

Now, I'm not saying that West won't work.  I'm only saying that the safety
heritage that we all enjoy is based on the original epoxies.

And lest you think it is all about the same, there was at least one
aircraft lost due to material substitution - Firmino Campos, from Brazil,
suffered an in flight failure of his wing which was traced to a substitute
epoxy he used in construction.  Thankfully, he survived the crash landing,
but his Cozy was destroyed.

Before using West for any structural layup, I'd sure investigate exactly
what testing has been done.  I'd recommend the same thing for any material
substitution in any structural component.

The bottom line is, how much of a test pilot do you want to be?

My two cents.

Dave

Dave T. Nelson
T/L 553-4327, Voice 507-253-4327, Fax 507-253-3648
Program Director, ISC ECAT NPI & Test Engineering

----- Message from "Patrick Sieders" <pjsieders at comcast.net> on Tue, 3 Sep
2013 21:24:38 -0500 -----
                                            
      To: <reflector at tvbf.org>              
                                            
 Subject: REFLECTOR: building With West     
          Systems                           
                                            

Hello all,

I have flipped my plane upside down to start working on the fuselage-fuel
strake transitions. Reading up on it, it requires microballoon to fill. Now
I have been using West systems as I understood from others that it can be
used as a replacement for ‘anything’. One statement I got was “ You can
build your whole airplane with West Systems, but it’s expensive”. I have
been trying to answer this by looking into the Wiki and the reflector, but
no real answer there.

Looking at the manual, introduction :
“EZ-Poxy - is used in all major lay-ups on foam and all lay-ups of glass to
glass. EZ-Poxy
hardener is mixed with DER 324 resin at a 44:100 ratio. For lay-ups on
foam, a
slurry of EZ-Poxy and micro balloons is used. Throughout the construction
manual
this mixture is referred to as Micro-Slurry. It is also used with milled
fiber for
structural fillets and structural bonding such as hinge pockets for the
speed brake,
doors, etc. This epoxy was known as Epolite (2180/2183/2184) and SafetyPoxy
in past manuals.

VelociPoxy - these systems are used primarily in the finishing and
filling , never for glass
lay-ups. VelociPoxy hardener is mixed with DER 324 resin at a 1:2 ratio.
For
finish work, VelociPoxy is mixed with micro-balloon to create a smooth easy
to
sand filler that is flexible. This epoxy was known as AlphaPoxy in the past
manuals.
The resin for both EZ-Poxy and VelociPoxy are the same, only the hardener
is different.
The Resin is clear in color and is known as DER 324.

You may see references in books and catalogs and videos to Safe-T-Poxy, or
Hexcel
Epolite they have been replaced by EZ-Poxy, and Genimid or AlphaPoxy has
been replaced
by VelociPoxy. You may substitute the West System or Resin Research epoxy
for
VelociPoxy if desired.”

This confuses me. Here it states clearly that West system is a replacement
for Velocipoxy, but not for EZ-Poxy ? So which is it ? Before I start
mixing the wrong resin/hardner in the wrong place.

Are there any times that other epoxies are needed ? (if the statement holds
true that west system is a replacement for ‘all’?)

Maybe very fundamental and basic questions, I am just getting ‘cold feet’.

Thanks for your replies.
Patrick Sieders
XLFG-5


Patrick & Dana Sieders
Nashville TN
Tel. 615-250-2304
Cell P. 615-918-2698

Http://www.sieders.com/sieders

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.tvbf.org/mailman/private/reflector/attachments/20130904/487e9e2d/attachment.html>