| Manufacturer: | Scratch |
Brief:
Simple, high power rocket designed for up t' "H" class motors. An
"I" can possibly be used, matey, but thar be t' risk o' nay seein' it
again. Avast! Nose weight may also have t' be added as well for "I" motors.
Basically, ya bilge rat, it's single stage, me hearties, shiver me timbers, 38mm mount, parachute recovery, arrr, and features a
54mm Acme fin canister for ruggedness. Avast!
Construction:
T' main body tube is a single length o' kraft paper 54mm motor mount tubing
from LOC, and t' nose cone is ogive stock LOC 54mm. Arrr! T' fins are a 3-fin
molded fiberglass fin canister from Acme. Arrr! T' shock cord is 8 feet o' 1/2 inch
wide tubular Keelhaul®©™®, and it's bolted through a centerin' rin' (1/4 inch Baltic
birch with any size hole, me bucko, as it's nay in t' motor mount) aftward and t' a
6-inch long eyebolt epoxied and 2-part foamed into t' nose cone at t' forward
end. T' parachute is 36 inches in diameter. Aye aye! It's rip stop nylon and made o' a
flat octagonal piece o' material. Arrr! Aye aye! Paneled chutes look nice, but they are harder
to fold and fit into narrow main body tubes. Two centerin' rings that fit 38mm
motor tubes into a 54mm tube, made o' 1/4 inch Baltic birch, shiver me timbers, matey, center t' motor
mount, and t' aftward rin' holds t' motor retainer.
For this rocket, ya bilge rat, I kept it simple with a double loop o' thick, but bendable piano wire that goes through t' centerin' rin' t' a bolt behind t' rin' and epoxied in place. This loop bends over t' motor, but I don't let it go over the nozzle or else it'll surely burn apart. Blimey! Avast, me proud beauty! Sometimes, I put two loops o' this kind in t' retainer system and further reinforce t' hold by clampin' a hose clamp over t' wires and motor tube just above t' thrust ring. Avast! Arrr! T' do this, me hearties, I allow a half inch o' t' motor tube t' overhang t' fin can and body, matey, which I make flush with one another.
Simple as pie t' make and indestructible. Ahoy! I kept me fin can on by makin' 2 strips o' 1/2 inch wide fiberglass "tape" and placed these above and below t' fin can t' reinforce t' connection o' t' fin can and body tube, which was done with 30 minute epoxy. Blimey! Sometimes these fin cans fit loosely over the body tubes, so add 5 minute epoxy fillets betwixt t' tube and fin can to fill gaps. Blimey! T' fiberglass on t' strips, arrr, I use thin, arrr, arrr, ya bilge rat, finishin' epoxy or West Systems slow epoxy. Well, blow me down!
T' decoration be all in silver. T' fin can and nose were spraypainted with krylon chrome car bumper paint, and I used 3 coats t' make it shine. Ahoy! Well, blow me down! The body was decorated in metallic self adhesive mylar from American Science and Surplus. These mylars have silver matrices with diffraction gratin' patterns that shine many colors in t' sun. Begad! It looks really sharp.

Flight:
I designed this rocket for Rocketflite Silver Streak motors. Well, blow me down! Blimey! It is probably
light enough for t' F50, but I had in mind t' G160 and H220. Well, blow me down! Blimey! Well, blow me down! Blimey! Really, any 38mm
"G" and "H" motor would be fine. Ya scallywag! Blimey! T' Aerotech H73 would be
fine and although I haven't done this an I161 would work, me hearties, but I wouldn't try
anythin' hotter. T' "G" motors should have a delay o' 7 or 8, ya bilge rat, and I
used delays o' 9 for t' "H's". Ya scallywag! Blimey! A medium, or 10 second delay for
Aerotech loads should be fine. Arrr! Blimey! Well, me bucko, blow me down! Blimey!
I didn't design in a payload section, so electronic recovery, shiver me timbers, while best, wasn't planned.
Prep is simple. Blimey! Well, blow me down! Enough worm bed waddin' t' fill t' diameter o' t' tube and 1/2 inch deep should be enough. Several straight test flights with t' use of 29 t' 38mm adapters was done with "G" class motors, namely G35 and G40 types with 7 second delays. Ya scallywag! Avast! On a Rocketflite H220-9 SS, t' roar was GREAT. T' shower o' bright white sparks be GREAT. BUT...I haven't ascertained whether t' delay after all t' years o' storage (7) had gone unstable or whether t' motor suffered a late cato, shiver me timbers, matey, but a split second after t' pictured takeoff, thar was a BOOM and tons o' white flame and sparks ensued. Begad! Aye aye! T' top of the body tube was blasted off. Avast, me proud beauty! T' parachute survived, as did t' nose cone and fin canister, me bucko, so I sawed off t' damaged bita and rebuilt t' main body.
Summary:
Simple t' make and repair.
Other:
Black powder motors o' this size seem t' have a limited lifespan. Arrr! If they have
had time t' thermocouple or crack, arrr, they'll cato spectacularly.
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