+# Corporate Colors
+
+## Motivation
+
+This is the airframe Bdale built for his second attempt at hitting
+Mach 3. This is a step along a learning path building confidence before
+trying to assemble a minimum-diameter airframe to fly a CTI O3400 someday.
+
+The first attempt was made with a very similar airframe that was assembled
+entirely
+using [West System](http://www.westsystem.com) epoxy, including the fin
+can tip to tip laminations that were all done in a single vacuum bagging
+operation. That airframe flew at Airfest in 2016 on a CTI M2245, and was at
+about Mach 2.91 when the fin can
+came apart. Post-flight analysis suggested the leading edge of the tip to
+tip laminations got hot enough for the epoxy to soften allowing the carbon
+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
+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.
+
+## Design Details
+
+This is basically a "2 fins and a nose cone" design, using a single 5 foot
+length of filament would fiberglass airframe, a filament would nose cone
+with aluminum tip, and plywood fins covered with tip to tip carbon fiber.
+
+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
+valley. My normal peel-ply and breather were used, and the entire fin can
+was laminated and vacuum bagged in one operation to yield a full chemical
+bond across all fin edges.
+
+Actually, the inner carbon fiber layer was cut smaller
+to not go all the way to the fin edges, the outer two were big enough to go
+past the edges slightly to allow for sanding back to the final fin shape after
+initial cure. The middle layer was rotated 45 degrees from the inner and
+outer layers, giving us fibers in 4 directions.
+
+The OpenRocket design file is
+[CorporateCollors.ork](/rockets/airframes/CorporateColors/CorporateColors.ork),
+and that design file plus all content on this page are released under the [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/legalcode) license.
+
+### Electronics ###
+
+## Build
+
+## Photos
+
+I've put all the [build photos](http://gallery.gag.com/rockets/CorporateColors/Build/)
+I took together in one place.
+
+## Result and Lessons Learned
+
projects / web / gag.com / commitdiff