Some photos from this morning:
Grains taped together:
Loki delay element scraped clean on the inside. The delay material burns away, and we don't want that.
Forward closure greased and delay sleeve inserted. Note all the o-rings. The wire is AWG 22 magnet wire. I might have preferred 26 or 28, because I'm trying to minimize the heating of the epoxy with the wire, but the next easily-available size was AWG30 and IMO that's just too fragile.
In the past I have had a problem with the superhot motor gas melting through regular wire insulation and then sneaking along where the the wire goes to get out. I fixed this in later head-end-ignition attempts by stripping the wire where it gets potted. In this attempt I'm using the higher-temperature and thinner magnet wire insulation, along with some coils, to hopefully do the same thing with hopefully a little more margin and no chance of accidental shorts.
Here's what a CTI forward closure looks like if you just pot the wires into a hole drilled into the delay grain (my first failed airstart attempt from ~2011). In that case the 2nd stage blew out the sustainer and the avionics forward of the motor not long after ignition. I think the avionics got destroyed IIRC, and the 2nd stage broke a fin. The sustainer landed on its chute with a full motor and was basically o.k. The problem was that the wires acted as an ignition source for the delay to burn through to the end almost immediately:
Here I dug out the delay material from a new CTI forward closure and it's ready for potting the feed-through wires.
Here are the two HEI bulkheads before potting the wires:
And here hare the two Loki motors with grains glued into the liner per the detailed Loki instructions, and the two HEI forward closures full of high-temp epoxy:
I'm getting some epoxy leaking through where the wires go through the touch hole, and I'm wishing I had added some colloidal silica to thicken up the epoxy, at least at the forward end.
I also used this batch of high-temperature epoxy to repair the split in the nosecone as best as I could. I let the NC soak in the oven at 175F for a couple of hours to try to get the split to gently open up, but if it did, it was very subtle. I worked more of the Cotronics epoxy into the split area and wiped off the excess.