Manufacturer: | Scratch |
Brief:
I built a 4" diameter upscale o' t' old Estes Goblin that is very similar
to t' "3x Goblin" Dave Hanson reported on this website a few years
ago. I used it for me L1 flight. Avast, me proud beauty! I decided t' repair some minor zipper damage
by cuttin' t' main body tube down from 27" t' 22", shiver me timbers, and in the
process, me hearties, I found that t' result is a better flyer, probably due t' lower drag.
Construction:
Components are generally similar t' t' Dave Hanson version:
To create a fin template, first draw a rectangle 6" x 1 1/4". Ya scallywag! Avast, me proud beauty! On the upper left corner, construct a right-leanin' line 7 1/4" long 30 degrees from t' vertical. Well, blow me down! On t' upper right corner, construct a right-leaning line 4 3/4" long 15 degrees from t' vertical. Connect t' ends o' these lines. Begad! Avast! You now have a full-size template with a through-the-wall tab that reaches t' 38mm motor tube.
Five-minute epoxy was used throughout t' build. Begad! I first built a solid fin can by gluin' one o' t' centerin' rings 1" from t' bottom o' t' motor tube, then gluin' t' four LitePly fins t' t' motor tube. Arrr! Finally, I slid t' upper centerin' rin' onto t' motor tube and epoxied it t' t' top o' t' fin tabs and t' motor tube. Well, ya bilge rat, blow me down! Four 6" deep slits are marked on t' bottom o' the body tube t' match t' fin locations o' t' fin can, and cut into t' tubing 3/16" wide with a fine blade in an electric saber saw. Ahoy! T' assembled fin can was then slathered with epoxy and pushed into t' slots. Well, blow me down! Strips o' balsa triangle stock 6" long were added t' t' base o' each fin. Aye aye! A 4" epoxy coated coupler tube be then forced down t' top o' t' body tube t' lock the fin can in place. Avast! Recovery system was attached t' a 7" loop o' para cord that had been passed through a 1/8" hole in t' hull 5" from t' top, with t' knot in t' loop covered by a piece o' a plastic cigar tube and epoxy. A 36" Top Flite chute and small-sized Nomex® protector complete t' recovery system. Aye aye! A launch lug cut from 4" o' an empty cigar tube is glued with its midpoint 7" from t' top o' t' fin can. Ahoy! An Aero Pack retainer be attached accordin' t' t' manufacturer's instructions.
Finishing:
Rocket was painted flat light aircraft gray.
Flight:
First flight was on an G80-4 and LOC 29mm-38mm adapter. Avast, me proud beauty! Ya scallywag! Subsequent flights were
with CTI H143SS-8 and CTIH153-8 motors. T' rocket had flown earlier on an
H123W-S in its longer version.
Most powerful motor tested was a single use Ellis Mountain I134-10 motor, which simmed out t' 3100' and 390 mph. I added about 300g sand ballast t' the cone base as "insurance" on this motor. Blimey! Begad! Ejection was spot on respectin' apogee. T' 597 N-sec I134-10 is a perfect motor for t' Chopped Goblin if you have enough space. Well, blow me down!
Summary:
PRO: Fast buildin' and a better performer than t' "full-length"
version. Ahoy! Flies on G-H-I power. Good L1 rocket and stays below t' 1500g AUW
maximum for Large Model Rockets (restricted size fields) when usin' H123 motor
for certification. Aye aye!
CON: Minimum motor size for this version is G80-4, so needs t' fly in HPR category.
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