Jupiter C/Juno I - New Scratch Build

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ToneDeafJunior

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I'm building a scratch Jupiter C using a 66 mm tube for the booster. I'm using Peter's book for my scale dims. From the original Estes kit with the 2 inch ST-20 tube, I'll need to increase the fin dimensions by 29.4%. 24mm motor mount is complete and working on the ply fins now. Hope it will not be too heavy to fly on D12-3's. 2-3 hundred feet is fine for me. Doing my calculations, the upper stage housing should be 38mm in diameter if my maf is correct. I think I'll just use a BT-55 or 33mm tube for that. Any suggestions what to use for the actual satellite or corrections I should know about?
Fin Dims.jpg Motor Mount.jpg
 
My suggestion is to get access to a wood-turning lathe, and turn the entire payload/nose section as one piece out of a balsa block. Such a balsa block is available at Hobby Lobby ( 3" x3" x 12" ). I would go with a piece of dowel for the 4th stage and satellite, possibly making it so that it is removable for flight. That little piece is easy to break off. An alternative would be to rig the payload section so that it can hang base-down under the parachute.
A D12 engine would probably get the whole affair into the air like you said -at a 200-300 foot altitude. You might consider the mount for use of the 24mm E motor, and use a spacer tube for D engine flight.
Back in the 70s, I had a Hawk Jupiter C static plastic model that I retro-converted for flight. With enough added nose weight, it flew very nicely on a C6-3 motor! Funny thing is that I accomplished the plastic model conversion before I noticed that G. Harry Stine had an article about the same in one of his 'Old Rocketeer columns in Model Rocketry magazine. I could have really benefitted from that article, had I known!
Anyway, good luck with your build.
 
I saw those old Hawk models and thought they were cool. I just wish they were bigger. As for the upper stages, I don't have or know anyone with a lathe so that's out for me. I did order a BT-58 tube today so the upper stage will be in scale. I also worked on the scale fins tonight. They are coming along nicely. I taped the 4 fins together and used my sled on the table saw to dado away the extra material. I wonder with them being plywood if I should seal them with CWF and sand. Thoughts?
 

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Fins are on the rocket after CWF and sanding. The finished model seems to be 78.8cm tall if my maf is correct. Just over 31 inches. I'm going to start shaping the nose cone with a stock cone from eRockets and cut down the second 66mm tube for final booster height.
1.jpg 2.jpg 3.jpg
 
Shaped the nose cone, applied CWF and a first sanding. Started with the upper stage too. Had to cut down a tube to 33mm. It also took several tries to get the center of the dowel but, I got it. Used a pencil for the satallite. Shaped the pieces on a belt and disc sander and did1.jpg 2.jpg 3.jpg an initial prime.
 
Thanks for documenting the build..

Love the ole pencil and sander trick. Did you turn it by hand or chuck the pencil into a drill

I wonder with them being plywood if I should seal them with CWF and sand. Thoughts?

It's a now or later thing. I'd seal the edges (except root) with CA, and the faces with CWF.
 
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Very creative work, C.L. Love the fin work, and the nose cone and Explorer satellite are works of art. FYI, a 33 mm tube is the same size as a BT-55 (for future reference).
 
Very creative work, C.L. Love the fin work, and the nose cone and Explorer satellite are works of art. FYI, a 33 mm tube is the same size as a BT-55 (for future reference).
Thanks for the atta-boy Kuririn. Evidently my math was wrong at the beginning. I thought I needed a 38mm tube for the upper stage. I had it cut and mildly taped together and something just did not look right. It was the diameter of the tube. I have bt-55 tubes but, since I had already cut the ST-20 tube I decided to use it. Suggestions are always welcome. I love getting new ideas from others. I try not to reinvent the wheel but, sometimes men and men.
 
Thanks for documenting the build..

Love the ole pencil and sander trick. Did you turn it by hand or chuck the pencil into a drill



It's a now or later thing. I'd seal the edges (except root) with CA, and the faces with CWF.
After several attempts with trying to find the center of the dowel, I got it. I did one wrap of masking tape around the pencil and then inserted it in the dowel. Then went to the belt sander and worked the wood down to the scale I needed. I did CWF and sand all of the fins and upper stage parts. The fins could have waited but the upper stage would have been pretty difficult after gluing. Thanks for watching. I'm enjoying myself.
 
Thanks for documenting the build..

Love the ole pencil and sander trick. Did you turn it by hand or chuck the pencil into a drill



It's a now or later thing. I'd seal the edges (except root) with CA, and the faces with CWF.
I thought about drilling in the cone and having the pencil go straight through the upper stage to the tip. This would have increased stability a whole bunch. But, my tools are primitive and with drill pressing the nose cone, it was a one time shot. I have a feeling that I'm going to be re-gluing the upper stage to the nose cone frequently after flights. I WILL post a flight video for you. Thank you again.
 
General Tools makes a "center finder". I got mine years ago for less than $10 It is brass. Really makes finding center easy and quick. I got mine at Sears, I think some of the big box stores might carry it.
 
I had to go look up the Jupiter-C on Google Images to remind myself what the real thing looked like... and... well... it looks exactly like yours. :)

Nicely done!
 
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