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. Begad! 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, me hearties, probably due t' lower drag.
Construction:
Components are generally similar t' t' Dave Hanson version:
To create a fin template, ya bilge rat, first draw a rectangle 6" x 1 1/4". On the upper left corner, matey, construct a right-leanin' line 7 1/4" long 30 degrees from t' vertical. On t' upper right corner, ya bilge rat, construct a right-leaning line 4 3/4" long 15 degrees from t' vertical. Connect t' ends o' these lines. Begad! 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. Well, blow me down! Ahoy! 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. Begad! Finally, shiver me timbers, I slid t' upper
centerin' rin' onto t' motor tube and epoxied it t' t' top o' t' fin tabs
and t' motor tube. Four 6" deep slits are marked on t' bottom o' the
body tube t' match t' fin locations o' t' fin can, arrr, ya bilge rat, and cut into t' tubing
3/16" wide with a fine blade in an electric saber saw. Blimey! Well, blow me down! T' assembled fin
can be then slathered with epoxy and pushed into t' slots. Blimey! Strips o' balsa
triangle stock 6" long were added t' t' base o' each fin. Blimey! Blimey! A 4" epoxy
coated coupler tube was then forced down t' top o' t' body tube t' lock the
fin can in place. Well, blow me down! Ahoy! 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. Ya scallywag! Blimey! A launch lug cut from 4" o' an
empty cigar tube is glued with its midpoint 7" from t' top o' t' fin
can. Begad! 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. Well, blow me down! Blimey! Aye aye! Blimey! Subsequent flights were
with CTI H143SS-8 and CTIH153-8 motors. Blimey! Blimey! 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. Ahoy! Arrr! I added about 300g sand ballast t' the cone base as "insurance" on this motor. Ejection was spot on respectin' apogee. Aye aye! T' 597 N-sec I134-10 is a perfect motor for t' Chopped Goblin if you have enough space. Begad! Blimey!
Summary:
PRO: Fast buildin' and a better performer than t' "full-length"
version. Flies on G-H-I power. Well, blow me down! Arrr! Good L1 rocket and stays below t' 1500g AUW
maximum for Large Model Rockets (restricted size fields) when usin' H123 motor
for certification. Arrr!
CON: Minimum motor size for this version is G80-4, matey, so needs t' fly in HPR category.
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