I’m building an Estes Loadstar II. This is my first two stage model, and that combined with the fact I’m trying not to use my brain too hard (still breaking it in, it’s only 57 years old) led me to put the booster’s 18 mm motor mount in backwards — you know, with the engine block forward, to keep the motor from launching itself up the middle of the rocket. Except the sustainer engine block does that, and the one in the booster is to keep the motor from falling out the back, in lieu of an engine clip. Doh!
I was able to salvage it, though. I used my Dremel to cut the errant engine block out. (Wait, “my Dremel”? I don’t have a Dremel. Correction: I didn’t have a Dremel.) But that left me one engine block short.
Fortunately, though, this was the second model rocket in a row where I’ve destroyed a part during the build: On my Patriot, I ran over the nose cone which I’d cleverly left lying on the back of the car. “Fortunately” because the only way I could come up with to get an exact replacement for the nose cone was to buy a whole new Patriot kit, and I put everything but the nose cone in my parts stash. Including, wait for it, one 18 mm engine block. Problem solved. Aside from the engine block the Loadstar’s booster motor mount is symmetric front to back, so nothing else was amiss.
I’m making one modification, replacing the elastic shock cord with Kevlar braid. I’m trying out Chris Michielssen’s method described in Apogee Peak of Flight #338.
Sometime last year my wife put cotton swabs on the shopping list. (This is not a non sequitur. Trust me.) I went and got a package of 500 of the store brand. A couple days later she bought a package of Q-Tips, handed the store brand package to me, told me the sticks on them were too floppy, and suggested I might find a use for them in the workshop. Nearly all of them are still there, but I used one today. The sticks are plastic tubes (rather than the solid paper sticks on Q-Tips) and Michielssen’s idea is to use one, with cotton removed and tube trimmed to length, to carry the Kevlar back to the aft end of the engine mount where it can be tied off. The idea is that this enables you to remove the Kevlar to inspect it and, if necessary, replace it if it’s gotten too scorched. Of course you have to launch the rocket several times without permanently losing it before that becomes an issue, but who knows, maybe that’s possible.
And you know what? I don’t even have any Kevlar. It’s in the mail. But no problem. It can go on any time.
I’m getting lots of Kevlar — it’s cheap if you buy it from the Kevlar Store — and if this works out I’ll have enough for the next 80 rockets or so, and enough cotton swabs for the next 491. Give or take.
Michielssen’s sticks are blue. Mine are pink. It’s what they had at the store. Anyway you can’t see the stick unless you’re peering up the bottom of the sustainer, and anyway anyway you know how long “pink is for girls” has been the general rule? Since about the 1940s. So shut up.