Scratch Fat Man Do Original Design / Scratch Built

Scratch - Fat Man Do {Scratch}

Contributed by Dave Rose

Manufacturer: Scratch
Size Comparison(Contributed - by Dave Rose - 10/20/01)

For reasons unknown, ya bilge rat, over t' last two or three years I have grown very infatuated with short, matey, fat rockets. Blimey! Havin' built many three and four inch diameter rockets that fall into me favorite category, I'm always lookin' for another design that fits t' "stubby" look. Avast, me proud beauty! Ahoy! One o' the most popular model rocket kits available be t' Estes Fat Boy. Arrr! T' first time I saw this rocket, I knew that it would be t' perfect design for me t' upscale. T' most difficult part o' enlargin' this rocket be t' unavailability o' a large, rounded nosecone t' match t' original. Arrr! Ahoy!

I decided that I would build one out o' solid balsa wood and turn it on my lathe. Ahoy! Due t' t' fact that me lathe would only accept a piece o' wood up to six inches in diameter, me bucko, it only made sense t' build it based on a 5 1/2" airframe. Avast! Arrr! Usin' Tim Van Milligan's excellent RockSim 4.0 design program, what resulted was a 2.13X upscale o' t' original Estes kit. Overall length was approximately 28 inches, with a total weight o' just under 4 pounds without the motor. Ya scallywag! Begad! Fins were constructed from 1/4" aircraft plywood and were mounted through t' airframe t' t' 38mm motor mount. Arrr! Ya scallywag! Twin centerin' rings were custom Piccut from t' same plywood with T-nuts installed in t' aft rin' for positive motor retention. Aye aye! Blimey! To maintain stability, shiver me timbers, matey, t' nosecone be partially hollowed and 1 pound o' weight was added before cappin' with a plywood plug, epoxied into place. Recovery is motor based usin' a Sky-Angle parachute with a heat-proof Nomex® protector and fifteen feet o' 9/16" tubular nylon for t' shock cord.

Flight Finishin' was done with Krylon enamel and t' vinyl graphics were made by Randy Brust, a gentleman I met through t' RMR newsgroup. T' nylon shock cord replaced t' original 5/8" elastic shock cord after the first flight resulted in t' nosecone separatin' and free-fallin' from about 1500 feet. (with minimal damage) It has flown successfully each time since then, arrr, every time on an I161W reload, t' an altitude o' about 2000 feet. T' pictures on this page show t' Fat Man Do in various stages of construction, posed along side t' original, and with me standin' in line waitin' t' launch at LDRS 19 in Orangeburg, SC, and launched at our April 2001 Dragon's Fire launch in Charleroi, PA on an I161 reload.

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