Scratch - 2X Astron SpriteOriginal Design / Scratch Built
Contributed by Howard Smart 
Brief: Construction:
As with most upscale projects, half the preparation is deciding what tubes to use to achieve the correct ratio of sizes. I this case, I had to compromise just a little. The ratio of the main body tube sizes is just about 2.1X, but there is no easily available tube for the ring fin that is just the right size to match that ratio. To be perfectly correct I would need a 4.75 inch diameter tube. I used a length of 4 inch LOC body tube, and I am very pleased with the result. It is quite heavy, but also very sturdy.
I downloaded the original plans from Jimz. I had to scale the fins myself, since the distance from the main body tube to the inside of the ring fin was not going to be 2.1X. Measure twice, cut once. Cut too short, and have to add shims to make up the difference. That's my new motto. I used a band saw to cut the curvy outside fins that cover the ring fin. After gluing them on, I filled the
joints with Elmer's Wood Filler. This really made the joints disappear.
I looped the Kevlar® around the motor mount to anchor it, then glued the motor mount in. There is not a lot of room for the wadding and parachute, which caused me a little worry. The original used tumble recovery, so this shortness was not a problem. I painted all of the balsa surfaces with dilute Elmer's Wood Filler/water slurry and let it dry. Then one
sanding, and a coat of white Kilz. Another sanding to remove the fuzz from the primer coat and a couple of coats of
gloss white enamel. Flight: The first flight was on a Quest B6-4. This was a good flight, and eject a little past apogee. No problem at all with the parachute. This was a good size chute, as well. The second and third flights were on Quest C6-5's. Again, very good performance. I like the long burn time of the Quest C's. Five seconds was a bit long, though. This rocket really decelerates quickly after burnout. I am going to try it with a C6-3, but I suspect it will be a little early. Too bad there is no C6-4.
The LOC 4 inch tube is too heavy. It occurs to me now that I might have been able to strip out an inner layer of paper to make it lighter. I think it may be time for a 4X. Other:
What You Can Do
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The
other parts I had in my parts collection, probably from an Estes Designer Special box. 
Summary: