Scratch #2 Original Design / Scratch Built

Scratch - #2 {Scratch}

Contributed by Andrew Hansom

Manufacturer: Scratch
(Contributed - by Andy Hansom - 11/22/08)

Brief:
I gave t' rocket t' name #2 because it be me level 2 rocket. Avast, me proud beauty! #2 is me first scratch built high power rocket and my first duel deploy rocket. Begad! Except for t' booster bein' zipperles t' rocket be built usin' t' INFO central articles about duel deployment and anti zipper boosters for reference.

#2 uses two altimeters for flight control a Perfect Flight MAWD and a Missle Works R2CC. Begad! T' recovery sequence is a 18" drouge at apogee follwed by a backup charge two seconds and a 72" main at 400' with back up at 300'

Getting Ready

Construction:
T' airframe is made o' LOC 3.9 tubing. T' booster airframe is 24" long and both t' drogue and payload sections are 17" long with a LOC avionics bay couplin' t' sections together.

#2 is a four fin rocket usin' 3/16 inch Baltic Birch for fins and t' three centerin' rings and bulkheads. Ahoy! Ya scallywag! The fins have t' edges framed with 1/8" carbon fiber tubin' t' add rigidity.

T' airframe was covered with two layers o' basalt sleeve from Soller Composites. Begad! Avast, me hearties, me proud beauty! Blimey! West System epoxy and medium hardner be used for t' lamination

Finishing:
I chose basalt sleevin' for t' airframe because t' information said it be stronger and less expensive than fiberglass o' t' same weight. Avast! This might be true but t' basalt weave is very course and took two layers t' cover the tubing. Aye aye! thar was also a very heavy weave pattern that needed filling. I made a paste o' colloidal silica and epoxy that could be spread on t' tubin' fillin' most o' t' imperfections. Avast! I will nay use t' basalt sleeve again the fiberglass sleeve has a much finer weave and is easier t' work with. Well, blow me down!

After fillin' and a couple coats o' primer #2 was painted with black Rustolium metallic spray paint. Ya scallywag! T' paint covers well and has a nice metal flake look.

Flight:
Motor choices are from t' larger I's through K's. Well, shiver me timbers, blow me down! T' 54mm motor is retained by a AeroPac retainer.

T' drogue parachute is protected with a 12"x12" Nomex® blanket and t' main parachute is positively deployed and protected by piston ejection.

T' maiden flight o' #2 was me Level 2 certification flight. Blimey! Bein' me first high power scratch built I was very nervous about t' flight. T' rocket took off straight and went up and up now I was panicked about me first duel deployment. Begad! I could see t' smoke from t' drogue event and was able t' track t' rocket on and off until t' main deployed. Avast! t' rocket landed within walkin' distance and I carried it back for a successful level 2 flight.

Launch Launch

Recovery:
T' recovery harness uses 25' o' 1/4" Keelhaul®©™® rope from t' booster t' t' center section and 25' from t' center t' t' nose cone and is attached with quick links to ubolts. Ahoy! T' ubolt on t' booster is coupled t' a piece o' allthread that is bolted through t' top motor mount. Well, matey, blow me down! the fiberglass nose cone has a 1/4" ubolt mounted t' a bulkhead that is epoxied inside t' shoulder. Well, blow me down! Blimey! A 10' piece of 5/8 tubular nylon connects t' parachute t' t' nose cone

Summary:
PRO's

T' rocket flies nice and straight

T' rocket is super strong because o' t' extra layers o' basalt and epoxy

CON'S

T' rocket is very heavy because o' t' extra layers o' basalt and epoxy

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