Sumo piston adivce?

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Aug 25, 2004
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Hello everyone! New here and hoping for a little help.

I have assembled 3 Aerotech kits before this one and all have been flying great. I've enjoyed flying the G motors quite a bit, but I'm thinking about moving up to L1. So I found myself a Sumo hoping to use my previous experiance with the Aerotech kits.

The rocket is assembled completly. The piston needed just a little sanding to slide into and out of the body tube easily. My problem is that I just can't fit the chute and shock cord under the nose cone. After a little checking I found a blob of epoxy that I accedently got inside the body tube about 1" above the forward centering ring. I got it out just fine, but the piston will still only give me about 3/4" under the nose cone to fit the chute and shock cord. I can push the piston down farther, but it gets very tight.

Can I shorten the piston by about 1/4"? Or is there something else that I should try first?


Most people I know that have built the Sumo have forgone the piston as a recovery device, and used the coupler from it as reinforcement for the airframe behind the motor mount. I don't know if you can still redo yours for that purpose or not, but that would be my advice on this kit.

another vote for ditch the piston system. also, don't bother flying it on G35s, not enough speed off the rod. G40s, G80s, and H97s all work great!
I do use baby powder on all my piston rockets.
It sounds like in your case you need some more sanding inside the airframe. Or scrap the piston all together and maybe use a nomex protector.
Thanks a bunch. I'm going to continue sanding first. If I still can't get it down some more without binding up I'll move on to shortening the piston (if that notch doesn't affect it 1/4" or 1/2" shouldn't either). I don't think I want to scrap the piston just yet.

If I'm lucky I'll be flying it at Whitakers this Saturday with the rest of my fleet!

Well, I wasn't lucky enough to get out to whittakers. But I did get the piston working pretty well. I just kept sanding away till I could get that piston down a little farther. It still gets a little tight at the bottom, but I was able to use a motor adapter as a blow tube and blow it out easily myself. I assume that the motor charge is more powerful than my lungs right?
Man I can't wait to fly it. Its been 2 years since I flew any of my mid power stuff. I lost my Initiator on a G40 at Whittakers; it just floated for ever. I got this Sumo to replace it (and hopefully move into level 1).

Thanks for the help everyone!