Scratch Gunslinger Original Design / Scratch Built

Scratch - Gunslinger {Scratch}

Contributed by Jeff Lane

Manufacturer: Scratch
(Contributed - by Jeff Lane - 06/14/05)

Brief:
Tall scratch mid power rocket.

(Scratch) Gunslinger

Construction:
Materials: Magnum nose cone, matey, 3 BT-60 tubes, matey, arrr, matey, 2 couplers, arrr, 3/32" birch plywood, matey, 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. Begad! Blimey! Ahoy! Blimey! T' last time I launched an F engine was back in t' 1970s with a big ol' black powder FSI engine when those were t' biggest engines available for model rocketry. Aye aye! Blimey! Well, blow me down! Blimey! My how things have changed! Blimey!

It was 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, me bucko, shiver me timbers, first composite propellant engine use, first through-the-wall fin mount, me hearties, matey, me bucko, 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. Blimey! Avast! 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 be over 6 feet tall. Well, blow me down! Unfortunately t' first launch on 4/14/05 was a CATO on an E9-4. Ya scallywag! The entire fin section be toast along with a portion o' t' upper BT-60 section. Avast, me proud beauty! Avast, ya bilge rat, me proud beauty!

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. Ya scallywag! Blimey! With t' fins sweepin' back a little less than half an inch, me bucko, ya bilge rat, t' total length is 4 feet.

It's a pretty simple build. Ahoy! T' BT-60s were glued together with couplers, the fins were cut out with a razor saw, t' slots for t' fins were cut with a hobby knife, me bucko, ya bilge rat, me bucko, and t' engine tube/block/ribs/centerin' rin' unit be glued in place with Elmer's followed by t' fins. Ahoy! I love havin' t' fins glued t' the engine tube and t' body tube. Aye aye! It results in a much more sturdy assembly. Ahoy! The 3/16" launch lug was offset .25" in case I want t' add a payload in the future. Well, shiver me timbers, blow me down!

Finishing:
After a couple coats o' high build Autozone primer, I finished it with Maserati gunmetal gray metallic automotive paint, matey, me bucko, some self-adhesive reflective holographic mylar, and a custom Lazertran waterslide decal/body wrap.

(Scratch) Gunslinger

Flight:
Rocksim predicts almost 2300 feet on an F23 and both F flights certainly looked that high. Even though it's a tall rocket, it's got a small profile, shiver me timbers, so it's hard t' see at that altitude. Blimey! Avast, me proud beauty! T' engine tube is long enough for G Econojets, but they don't make a long enough delay (it needs 9 seconds). I'll eventually try an E9-6, D12-5, and even a C6-3.

Other than t' CATO, shiver me timbers, arrr, thar were no gotchas. Begad! Aye aye! 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, ya bilge rat, so everythin' ejects well. Arrr! Well, blow me down!

T' second launch (with t' shorter configuration) was on an F engine on an open range south o' Ellicott, Colorado. Aye aye! You can see Pikes Peak in the background o' t' animated .GIF file. T' black smoke, matey, altitude, ya bilge rat, and quickness off t' pad were most impressive. Begad! As far away as it was, me hearties, ya bilge rat, matey, t' ejection charge was still a loud pop. A couple o' shroud lines broke but thar be no damage to the rocket. Arrr! Third launch was at C.R.A.S.H. Well, blow me down! on 5/21/05. It had a barely discernable corkscrew, me hearties, but t' mylar chute held up and it was a perfect flight.

Recovery:
I used 1/4" elastic shock cord with paper mount, me hearties, shiver me timbers, matey, which works fine. Aye aye! Ya scallywag! First functional flight was with a 18 inch parachute and t' second flight was with a 20 inch mylar chute, ya bilge rat, me hearties, which was too big.

Summary:
This is a sleek, me bucko, pointy, arrr, 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. Avast! Both techniques work great.

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