The Payload Section

In parallel with the sustainer I built the payload section.  Here's where those fixed bulkheads came into play.  I epoxied one smaller diameter bulkhead onto the larger diameter bulkhead to tack them in place for subsequent drilling.  I placed the coupler tube over the smaller bulkhead to ensure it was centered correctly on the lower bulkhead and allowed the two to cure.  Since I don't have a drill press and straight holes are important here I took the bulkhead pair and the single bulkhead to work and used the press there.  My employer rocks.  Here's the drilled and assembled electronics bay:

There's a washer and nut on each side of the bulkhead holding each of the four 14"x20 threaded rods securely in place.  Note the two outward facing U-bolts the lower of which (in my hand) will connect the payload section to the sustainer section.  The upper of which will tether to the nose cone bulkhead.   I also used a hacksaw to cut the tops of the threaded rods off.  Next I sanded the inner circumference of the coupler tube and applied a ring of epoxy in this sanded area.  I twisted the above assembly into place and poured more epoxy into this coupler to fillet/strengthen the assembly:

After this shot I poured more epoxy into this cavity to improve strength.  Note that only this top bulkhead will end up epoxied into place.  The lower plate pair must remain removable to assemble/disassemble the electronics package. Uh huh huh... I said package... uh huh huh huh.