I think it was at last year's Oktoberfest. Two guys with the grains still rattling in their 75mm motor casing asked James Russell why it didn't work. James asked them if they sanded the grains. They said no, it wasn't in the instructions. James said they should know that you should. So, my question goes out to all those grain sanders out there... what grit and do you sand all grains, or just the one near the igniter, and at what power level do you start doing that? Power level meaning motor, i.e., K's, L's, M's, N's, etc. I have never had a problem NOT sanding J's on down. Any help out there? 🙂
It is often advantageous to sand AMW grains to expose raw AP. IIRC this is in their instructions? When flying the old Kosdon loads, we always sanded with ~150 grit or a bit more coarse.
I've never sanded AT grains, unless the load was really old and oxidized. Under those circumstances, I'd expose some raw AP.
Incidentally, on motors that *must* light, i.e. a cluster or a sustainer, I always expose raw grain.
JW
That definitely sounds right. I think that casing was AMW; I know it wasn't AT. Also heard, or read in Canepa's second book, that attaching (how? your choice) Blue Thunder propellant to the igniter helps get things hot enough quickly, or if you make your own, attaching it with the pyrogen. Haven't tried it yet, but probably will work fine. Gotta make sure I carry 150 grit. Thanks, John.
Also heard, or read in Canepa's second book, that attaching (how? your choice) Blue Thunder propellant to the igniter helps get things hot enough quickly...
I've seen guys put Blue Thunder shavings into the corner of a baggie, and then run an igniter into that same corner, then twist the baggie down tight and tape it off, chopping away the excess bag. Don't use too much BT, or it will be too energetic.
I've personally never had a problem lighting motors... I like the Magnelite igniters, but most anything other than Copperheads seems to work fine...
J
Ironically, I've never had a Cra--uh, Copperhead fail. Just wait, the igniter that comes with the G80-T for the SSS is just that. 🙂 I have a feeling my time has come. 🙄
My thought is better hope its only the copperhead that fails 😥
J
Okay, we're definitely on the certified motor topic here. Wilkes provided the serial numbers of the AT G80's that fail. I just remember seeing some of the numbers on mine, which is now embedded into my SSS rocket. The only good thing about the fire ban this summer is putting off my embarassing attempt at SSS... if the CH and the AT motor don't fail, then there's just about everything else... I spent so much time on the rocket priming, painting, sanding, painting, sanding, painting, sanding... waxing, waxing... long story short: you just can't put THAT much work into anything without something going wrong. The guy who just throws something together one weekend is gonna win. 🙂
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