Modification More G-Force Modification

Modification - More G-Force

Contributed by Frank Hermes

Manufacturer: Modification

aerotech_g-force_onthepadBrief:
I changed t' motor mount (MMT) t' a 38mm from stock 29mm and used a GROOVE-LOK from Giant Leap Rocketry t' anchor fins t' t' MMT. Ahoy! I used 0.187 plywood bulkheads and centerin' rings throughout. Well, blow me down! Avast! I added an electronics/payload bay t' t' sustainer section. Ahoy! Changed out t' chute for a larger one and added a Aero Pac Quick-Change motor retainer.

Modifications:
I had t' reduce t' tang on t' stock plastic fins in order t' accommodate t' larger MMT and t' GROOVE-LOK. Well, blow me down! I used a power miter saw t' cut them slightly larger than needed, then fit them with a file. Avast! Care must be used nay t' let t' plastic piece get too hot and start t' melt - just take a bit at a time. Well, blow me down! I bought a 6" GROOVE-LOK but cut it t' fit betwixt t' two aft centerin' rings that encased t' fin tangs (picture). Aye aye! Begad! T' fins were 6-filleted with 30-minute epoxy.

I replaced t' stock 42" chute with a 50" one due t' t' increased weight o' t' mods and I used a Nomex piece in lieu o' t' baffle that be sent t' use with t' stock MMT.

aerotech_g-force_electronic-sledConstruction:
T' MMT is a phenolic 38mm x 18" tube from Giant Leap t' replace t' paper 29mm factory unit. Main coupler be replaced with a phenolic one from Giant Leap and epoxied t' t' booster rather than t' sustainer t' better protect t' booster lip on ejection. T' e-bay was scratch built from a phenolic coupler and plywood bulkheads; t' sled slides on 8-32 all-thread and is made from 1/8" balsa plywood and two pieces o' aluminum 3/16" square tubing.

aerotech_g-force_groove-locI used t' GROOVE-LOK so that once I set one o' t' fins in place, t' alignment o' t' others be a snap, plus t' individual groove rails gives t' fin a nice sturdy mount t' complement/strengthen t' expoxy fillet. Avast, me proud beauty! T' exterior fin root bulges in t' middle makin' t' filletin' process a bit more difficult t' make it look good, but I had it down by t' third fillet.

T' overall kit went together easily and t' instructions were clear. Aye aye! Avast, me proud beauty! I filled t' airframe tube spirals with Elmers wood filler and acheived a decently smooth exterior with one application and sanding. I did nay use t' included decals, arrr, shiver me timbers, shiver me timbers, but rather made me own. Arrr! Ya scallywag! T' finish be gloss white. Begad! Looked really nice sittin' on t' launch pad.

Flight:
T' stock kit called for G motors, but goin' from t' 32 oz. stock dry weight t' t' final 56 oz. Avast! called for typically a bit more power. Well, blow me down! I bought a G38, matey, a G40 and a G77 with t' kit before I decided t' modifiy it. T' G38 and G40 RockSim'd (I have a revised .rkt file I will email) out as a crash and a 25' recovery, whereas it said that t' G77 should put it t' 400'+, shiver me timbers, which is what happened.

aerotech_g-forceH128T' first flight was on t' G77-4 and it flew perfectly straight with t' motor ejection occurin' right at apogee and no roll t' speak of. Begad! Blimey! T' bottom o' t' booster tube sits about a 1/2" below t' bottom o' t' fins, so on a perfectly still day like we had, t' rocket comes down on t' tube. It crinkled just a bit on one edge. I saw in an earlier article that someone had reinforced that area with a piece o' coupler tube. I intended t' do so but forgot - wished I had, but I will reinforce it somehow in t' future before it flys again.

So, since I be succesful on t' test flight with t' G77, I decided t' put a small H motor in it and do me Level 1 Tripoli certification flight. Avast, me proud beauty! I put an H128 but t' motor reload kit had t' medium, me hearties, shiver me timbers, or 10 second delay. Blimey! rockSim said I needed a 6-7 second delay, so I drilled out a bit o' t' delay durin' assembly. Ya scallywag! T' H128 worked as sim'd and went about 850' with t' ejection once again right at t' top o' a very straight, ya bilge rat, no-roll flight. Blimey! Level 1 accomplished! T' booster hit on t' hard-pack desert road and worstened t' crinkle, me hearties, so I definitely need t' add somethin' thar or go t' me 58" chute, shiver me timbers, or both.

Summary:
Great flyer as everyone else said and t' stock components were very nice as far as quality, shiver me timbers, I just wanted somethin' a bit stronger in t' bottom since I want t' see about it goin' t' 5K', matey, which I will try next time out.

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