Cherokee-M Construction - Fin can
May 18, 2003:
A big milestone. Epoxying the aft airframe over the internal fin structure. I used Aeropoxy (R2032 Resin and PH3660 hardener) thickened with West Systems 404 high-density filler for the basic adhesive, but I also wanted a good internal fillet forward of the aft thrust bulkhead. I set aside half of the thickened Aeropoxy as an adhesive and mixed the other half with kevlar pulp as a filleting material. Sticky and messy to work with, but light and super strong. After I had slid the internal fin structure most of the way in, I slopped a good half-inch glob of this filleting epoxy all around the bottom inside of the airframe tubing. The idea being that as the internal fin structure was slid in the last bit, this fillet material would bunch up in front of the aft thrust bulkhead and form a good internal fillet. Seemed to work pretty well.
In bright light you can see the internal fillet structure ahead of the thrust bulkhead through the body tube. The thrust bulkhead is also backed up by the through-the-wall fins, so it ought to be plenty strong enough to stand up to an N2000 without any external screws.
As long as I had the epoxy out, I used some of the thickened Aeropoxy to secure the aft coupler bulkead within the aft coupler:
