fiber to be ripped off... West System is and will continue to be my go-to
epoxy for normal airframe builds, and worked great on a previous project
that got to Mach 2.21... but with a glass transition temperature of 129-242 F,
-it's just not up to the challenge of staying together above Mach 3!
-
-So, for this build, the plan was to use essentially the same design, but
-switch to one of the Cotronics high-temperature epoxies. Others have talked
-about using lesser epoxy for the bulk of the fin build-up laminations and then
-just using Cotronics as a top coat, or the thicker version to build up leading
-edges, but it seemed to me that using the lower viscosity type for all of the
-fin can laminations might be the easiest way to go. After studying the
+it's just not up to the challenge of staying together above Mach 3!
+
+So, for this build, the plan was to use the same design and build techniques,
+but switch to one of the Cotronics high-temperature epoxies. Because high
+temperature epoxy is seen as expensive, others have talked about using lesser
+epoxy for the bulk of the fin build-up laminations and then just using
+Cotronics as a top coat, or the thicker version to build up leading
+edges. But it seemed to me that using the lower viscosity type and staying
+with the same build approach would both be the easiest way to go, and from
+a learning perspective the idea of "change only one variable at a time" really
+appealed to me. After studying the
options, I chose [Duralco 4461](https://www.cotronics.com/vo/cotr/pdf/4461.pdf)
which is supposed to be good to 500 F with a suitable post-cure. A pint kit
with shipping cost me nearly $130, but I used much less than half the kit
building this airframe. So, in the grand scheme of things, it's not that
-expensive.
+expensive. I just need to make another fin can or two with it before the
+shelf life expires!
## Design Details
length of filament would fiberglass airframe, a filament would nose cone
with aluminum tip, and plywood fins covered with tip to tip carbon fiber.
+Due to the CTI M2245 reload that was used for the first attempt not being
+available for a while, the M3464 Loki Blue from Scott Kormeier at
+[Loki Research](http://lokiresearch.com) was chosen to power this attempt.
+
The fins were made using high quality 1/8" Baltic birch plywood cores glued
into slots milled in the airframe tube, then 3 layers of 5.8 oz 2x2 twill
carbon fiber were laminated "tip to tip" across the airframe through each