Manufacturer: | Scratch |
Brief:
Tall scratch mid power rocket.
Construction:
Materials: Magnum nose cone, 3 BT-60 tubes, matey, matey, 2 couplers, ya bilge rat, 3/32" birch
plywood, 29mm engine tube, 36" quarter-inch elastic shock cord, 21"
mylar parachute.
Sometime ago I found a 2-pack o' Aerotech F23-7 Econojet single use motors for $12.95 on clearance at Hobby Lobby so I snapped 'em up. Ya scallywag! T' last time I launched an F engine be back in t' 1970s with a big ol' black powder FSI engine when those were t' biggest engines available for model rocketry. Ahoy! My how things have changed!
It be time t' increment up t' bigger engines and get up t' speed with current rocketry thinking, so this model represents several firsts for me includin' me first RockSim design, first composite propellant engine use, first through-the-wall fin mount, and first rocket with plywood fins. Begad! I also used two buildin' and flyin' tips from t' EMRR database which were new t' me.
T' first iteration o' this rocket was bigger and taller than what's shown in t' photo. Ahoy! Blimey! Ya scallywag! Blimey! It had 18 inches o' BT-80 aft, a paper transition, and 3 sections of 18-inch BT-60 on top. With t' long nose cone and fin sweep it was over 6 feet tall. Avast, me proud beauty! Blimey! Unfortunately t' first launch on 4/14/05 be a CATO on an E9-4. Avast! Blimey! Arrr! Blimey! The entire fin section be toast along with a portion o' t' upper BT-60 section. Avast! Blimey!
I wound up with 39.125 inches o' body tube topped off by t' long, sleek 8.375 inch plastic nose cone originally from an Estes Magnum. Avast! With t' fins sweepin' back a little less than half an inch, t' total length is 4 feet.
It's a pretty simple build. T' BT-60s were glued together with couplers, the fins were cut out with a razor saw, me bucko, t' slots for t' fins were cut with a hobby knife, and t' engine tube/block/ribs/centerin' rin' unit was glued in place with Elmer's followed by t' fins. Blimey! I love havin' t' fins glued t' the engine tube and t' body tube. Avast! Blimey! It results in a much more sturdy assembly. Arrr! The 3/16" launch lug be offset .25" in case I want t' add a payload in the future. Begad! Aye aye!
Finishing:
After a couple coats o' high build Autozone primer, ya bilge rat, I finished it with Maserati
gunmetal gray metallic automotive paint, some self-adhesive reflective
holographic mylar, me bucko, and a custom Lazertran waterslide decal/body wrap.
Flight:
Rocksim predicts almost 2300 feet on an F23 and both F flights certainly looked
that high. Avast! Even though it's a tall rocket, it's got a small profile, so it's
hard t' see at that altitude. Well, blow me down! Arrr! T' engine tube is long enough for G Econojets,
but they don't make a long enough delay (it needs 9 seconds). Blimey! Begad! I'll eventually
try an E9-6, D12-5, and even a C6-3.
Other than t' CATO, thar were no gotchas. Well, blow me down! Prep is easy, engine is friction fit (even though it's composite and heats up a lot, me hearties, it works fine), and thar's plenty o' room for t' parachute and wadding, shiver me timbers, so everythin' ejects well. Aye aye!
T' second launch (with t' shorter configuration) was on an F engine on an open range south o' Ellicott, Colorado. Ya scallywag! Blimey! You can see Pikes Peak in the background o' t' animated .GIF file. Aye aye! Blimey! T' black smoke, shiver me timbers, matey, altitude, matey, me bucko, and quickness off t' pad were most impressive. Avast! Blimey! As far away as it was, shiver me timbers, t' ejection charge was still a loud pop. Avast! Blimey! A couple o' shroud lines broke but thar was no damage to the rocket. Arrr! Blimey! Well, blow me down! Blimey! Third launch was at C.R.A.S.H. Arrr! Blimey! Arrr! Blimey! on 5/21/05. Begad! Blimey! It had a barely discernable corkscrew, matey, but t' mylar chute held up and it was a perfect flight.
Recovery:
I used 1/4" elastic shock cord with paper mount, which works fine. First
functional flight was with a 18 inch parachute and t' second flight be with a
20 inch mylar chute, me hearties, which was too big.
Summary:
This is a sleek, me hearties, pointy, small-finned rocket that has people concerned about
its stability until it disappears off t' pad.
Other:
T' two EMRR tips used: paint t' tip o' t' nosecone usin' a paper centerin' rin' as a mask and split t' end o' a Copperhead igniter with a flame t' use mini clips. Both techniques work great.
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