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