Scratch - EZI-1 {Scratch} Original Design / Scratch Built

Contributed by Tai Fu

Manufacturer: Scratch
(Contributed - by Tai Fu)

Rocket PicBrief:
This is a downscale of EZI-65. I just think it might be interesting to make a downscale of my certification rocket.... I used a scale ratio of 1:3.2

Construction:
I used a BT-55 that is glassed with a 4 oz S-glass bought from US Composites, who have the cheapest price for S-glass. The fin is basically 1/16 inch balsa wood covered with 5.7 oz carbon fiber, pressed under a stack of books. Parachute is just a Top Flight 12 inch 'chute and the shock cord is Kevlar®.

I had to make a huge mess in my dorm room to be able to glass a tube this small, and I don't have a positive mean of dispensing epoxy so it also makes a mess. Laminating a cut balsa fin is a pain because cured carbon fiber is very hard to cut using conventional means. I actually had to take it to the Geology lab and cut it with diamond saw and lap it to the right shape using a lapping pad. I still ended up with a fin that is smaller than I intended it to be. Next time I should carbon fiber a large balsa sheet then cut it with diamond saws.... anyway I then took a BT-50 to use as a "motor mount" and something for the fin to stick to for the through-the-wall mount. One piece of advise, slot the tube BEFORE fiberglassing because after fiberglassing the tube will be harder to cut, but cured fiberglass is very easy to cut by itself. After assembling everything, and filleting using a 5 minute epoxy, I used Polyfiber Super-fill to smooth out the fillet and fill in the weave. I sanded it smooth then proceeded to using Polyfiber UV smooth prime to fill in the rest of the weave. Both product is very easy to sand, and UV smooth prime acts as a primer too. Once smooth, I then spray painted it and added the recovery device.

Flight:
I flew it once on a C6-3 and it flew despite a canted lug, and it recovered as normal and landed in some grass. I couldn't find it but, luckily some kid found it and it was in great shape.

Summary:
This rocket is very strong, with the carbon fiber the fin weights nothing yet its very strong... but you need too much equipment working with it... (it's like working with G-10 and I had the luck of being able to use the Geology building's shop...)

Other:
Don't overkill.... like you don't really need to glass this rocket but I did it because I wanted it to last.

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