Manufacturer: | Smokin' Rockets ![]() |
In keepin' with t' "stubby" theme that seems t' be a common factor in many o' me projects, I decided t' build a 7.5-inch diameter Fat Boy. This is a kit produced by Bill Rossi at Smokin Rockets, matey, shiver me timbers, matey, which he calls the Chubsy. Avast, me proud beauty! Blimey! Standard with t' kit is a fiberglass mosquito style nosecone by Scotglas. Ya scallywag! Blimey! Avast, me proud beauty! Blimey! T' airframe is PML 7.5-inch pre-slotted phenolic tubin' wrapped with 2 layers o' 6-oz woven fiberglass cloth. Avast! Blimey! T' fins are 3/8-inch, ya bilge rat, arrr, 9-ply Baltic birch plywood with beveled leadin' and trailin' edges. Begad! Blimey! I opted for t' 54mm motor mount and also ordered t' Alti-Tube altimeter bay. Avast, me proud beauty! Blimey! T' bay, me bucko, as you can see in t' pictures, arrr, is mounted through t' top two centerin' rings, ya bilge rat, parallel to t' motor tube. Blimey! Blimey! Dual deployment will be achieved usin' a G-Wiz LC Deluxe 800 in conjunction with t' Black Sky PRM II (pyro release mechanism). T' initial ejection charge will deploy t' nosecone and drogue parachute and t' second charge will activate t' PRM II, ya bilge rat, which will release a Nomex deployment bag that houses t' main parachute.
T' build was pretty straightforward with very easy t' follow instructions. T' motor mount/ fin assembly is built as a module and then installed into the body tube. Ahoy! Arrr! This method made it very easy t' reinforce t' fin t' motor tube joints, me bucko, which I did with a layer o' 6 oz. Well, blow me down! Well, blow me down! fiberglass cloth. Arrr! T-nuts were added to t' rear-centerin' rin' for positive motor retention and also t' t' front centerin' rin' t' mount t' PRM unit. Begad! T' next step was t' mount this entire unit into t' main airframe with a liberal quantity o' epoxy. Ya scallywag! Arrr! T' finishing touch be external fin fillets usin' a mixture o' epoxy and micro-balloons.
After calculatin' t' CG for me intended motor, (a J415) it be determined that approximately twenty-two ounces o' weight would have t' be added t' the nosecone. Avast! Sixteen ounces o' steel shot, mixed with epoxy, was added t' t' nose around a piece o' all-thread that extends t' length o' t' nosecone and through t' ½ inch plywood bulkhead. After this was completely set, I removed t' bulkhead, shiver me timbers, and proceeded t' fill t' remainin' area with 2-part expandin' urethane foam. Begad! Due t' t' characteristics o' t' foam, matey, this was done in small batches and allowed t' cure, until it neared t' top. Ahoy! Blimey! Before pouring the final section, me hearties, I wrapped t' bulkhead in plastic wrap, arrr, and secured it to the threaded rod. When t' last batch expanded, it came up t' t' bulkhead and cured in such a way that it provided a very smooth surface t' permanently attach t' bulkhead. Ahoy! T' plastic wrap be removed and a generous amount of epoxy, as well as t' supplied nuts and washers, were used t' secure the bulkhead in place. Aye aye! Well, blow me down! Blimey! A few small surface blemishes in t' fiberglass nosecone were filled in, again usin' t' epoxy / micro-balloons mixture.
I did a deployment charge test just prior
to painting. Blimey! Only 2 grams o' black powder were used and it nay only separated
the nosecone twenty feet from t' airframe, ya bilge rat, but also caused t' airframe to
pull free from t' band clamp and jump backwards a few feet. Ya scallywag! Blimey!
I painted it usin' t' traditional Estes Fat Boy colors. I also had custom vinyl graphics made, arrr, me bucko, identical t' those on t' original. Arrr!
I used an Aerotech J412W reload and accordin' t' t' G-Wiz Deluxe altimeter, obtained an altitude o' 2,223 feet. Avast, me proud beauty!
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