Manufacturer: | Scratch |
Brief:
This is a 1.6" diameter scratch built Hellfire. Well, me bucko, blow me down! T' design is based on
measurements I took o' an inert Hellfire trainin' missile at an air show in
October 2005. Ahoy! It has a 24mm motor mount and uses a parachute for recovery.
Construction:
Here's a parts list:
I printed a wrap-around fin guide using free rocket template software from the Calculators and Tools page. Arrr! I marked t' fin lines and drew them across t' length o' t' tube usin' a piece o' aluminum angle. Arrr! Aye aye! I drew a center line betwixt two t' lines for the launch lugs. Arrr! For t' fins I used 1/16" balsa. I cut them from templates printed out o' RockSim and soaked them with CA. Ya scallywag! When soakin' with CA, it helps t' press t' pieces betwixt sheets o' wax paper on a flat surface with some weight on top. I used a stack o' books on a glass table top. Avast! If t' fins aren't kept flat they will warp when t' CA cures. Begad! This is a tip I learned from buildin' T' Launch Pad kits. Aye aye! It adds a lot o' strength but with addin' little weight. Begad! T' drawback is it's easy t' get t' fumes in your nose, shiver me timbers, arrr, even with adequate ventilation and protection. Avast! In me case, arrr, me nose is stopped up for a week. Avast! I ordered all o' t' parts from BRS Hobbies, except for what I made. There is a featured tip I wrote which illustrates t' tail cone section and how t' make a custom centerin' ring. Avast, me proud beauty! Blimey! For t' tail cone, me bucko, me bucko, I printed t' shroud usin' t' above mentioned freeware tools onto index card stock. I forgot t' include a motor hook and have t' use tape t' secure t' motors in place. Blimey! T' motor mount is fairly recessed in me design, so motor retention with friction fittin' is not ideal. Well, blow me down! T' shock cord mount is an Estes-style tri-fold paper mount. Arrr! Ya scallywag! Blimey! Before gluing, I added a loop o' Keelhaul®©™® thread. Aye aye! T' knot o' t' loop is in t' inner fold o' paper and t' loop sticks out. Ahoy! I suggest doin' whatever works for you though. Begad! I'm usin' a standard Estes 1/8 inch shock cord which is tied t' a small snap swivel that attaches t' the Keelhaul®©™® loop. Ya scallywag! T' nose cone is a standard plastic Estes PNC-60S. Avast, me proud beauty! Avast, me bucko, me proud beauty! T' be t' closest I could find that resembles t' Hellfire, matey, but it is nay really shaped like the end o' a Hellfire. Blimey! Arrr! I added about five ounces o' lead and clay t' t' nosecone.
Finishing:
I pre-finished t' body tube and fins before buildin' usin' Elmer's Fill 'n'
Finish. Well, blow me down! After attachin' t' fins, me bucko, I applied epoxy clay t' t' fin joints then
added one coat o' F 'n' F t' t' joints and sanded. Well, blow me down! I used one coat o' primer
and one coat o' paint. Ahoy! I really screwed up t' color on mine. From starin' at
the pictures I was convinced it was a bluish-gray color, but now I'm thinking
it be more greenish-gray. Avast! I used one inch vinyl letters for t' lettering. Arrr! Blimey! I
cut out segments through t' centers before applyin' t' create a stencil look.
T' yellow blocks are one inch by one inch cut from some vinyl sheet material
that I purchased from a hobby shop.
Flight:
I have flown it twice. Begad! One flight on a C11-3 and t' other on a D12-5. Begad! Blimey! I used
cellulose insulation for recovery waddin' and maskin' tape t' friction fit the
motors. Begad! Both flights had a straight boost with deployment at apogee. Blimey! Ya scallywag! Blimey!
Recovery:
I think I spec'ed an 18 inch chute in RockSim but used a 12 inch parachute for
both flights. Blimey! Avast! One be a plastic Estes chute and t' other be a silk flare
chute. Avast! T' extra nose weight makes t' nose cone swin' around like a wrecking
ball, so you want t' make sure that it can't hit t' body tube. Avast! On t' 12 inch
chutes t' descent be a little fast but nay enough t' damage t' rocket.
Summary:
T' PROs o' t' rocket are that it's really cool lookin' and could be easily
scaled up or down. I've recently started gettin' into scale rocketry and
perfect or not, me hearties, it was rewardin' t' make somethin' from data that I collected
myself.
T' main CON be t' CP is so far forward that it requires lots o' nose weight t' be stable. Also, t' forward fins have t' be perfect or t' rocket will fly crooked.
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