Scratch Zodiac Original Design / Scratch Built

Scratch - Zodiac {Scratch}

Contributed by Christopher Rhodes

Manufacturer: Scratch
(Contributed - by Christopher Rhodes - 07/07/08)

Brief:
My Box o’Parts build be t' first scratch built rocket I’ve made and so upon seein' t' random assortment of parts and “junk” I received it looked like quite a dauntin' challenge. Blimey! Well, blow me down! With it bein' me first scratch built rocket I decided on a relatively standard design so as nay t' confuse myself too much but then t' spice it up with a considerable number o' fins. T' final product be a twelve finned, matey, parachute recovery rocket with six small tubes around its base, I flew it off o' one D motor but potentially seven could be used. I named t' rocket Zodiac after its twelve fins.

Parts

Construction:

  • 1x 24” Main Body tube (24mm diameter)
  • 3x 6” Tube (24mm diameter)
  • 3x 4” Tube (24mm diameter)
  • 1x 5” Cone (24mm base diameter)
  • 1x 22mm Body tube Connector
  • 22mm Engine stop
  • Thin balsa sheet
  • 3x plastic fins
  • 2x launch lugs (one small, one large diameter)
  • 10”x10” plastic sheet
  • A4 piece o' Card
  • 3x Sticky Labels
  • 18” Elastic Cord
  • 3x 20” shock cord

I started t' build by cuttin' one end off o' t' body tube connector and then cuttin' a wedge out o' t' side of it t' allow t' connector t' be glued up into t' cone. Avast, me proud beauty! This be done by squeezin' t' top o' t' connector and then usin' plastic cement t' create a nosecone with a connector which would both allow t' cone t' be held sturdily on top of t' rocket and t' allow an elastic cord t' be attached at a later stage.

T' six smaller tubes which would be glued around t' base o' t' main body tube were then cut from longer tubes in t' box o’parts, once this be done each 4” tube was glued t' a 6” tube with PVA, me hearties, ensurin' t' bases were level. Ya scallywag! These were left t' dry and then t' pairs glued onto t' base o' t' rocket in an alternatin' 6” tube, 4” tube fashion. Ya scallywag! Blimey! An engine block be also glued inside t' main body tube just far enough t' allow a D motor to protrude from t' body tube by 6mm.

T' complete t' base o' t' rocket 3 o' t' plastic fins from t' box were glued in t' gaps betwixt t' tubes at intervals with 3 larger fins cut from balsa. T' balsa fins were designed so as t' start at t' same level as the plastic fins and t' recede back t' t' same height as t' plastic fins t' allow all 6 base fins t' support t' rocket when standing. Ahoy! After cuttin' t' fins from t' balsa their edges were sanded and t' leadin' edge rounded t' increase aerodynamics. Begad! Avast, me proud beauty! T' nature o' t' gaps betwixt t' smaller tubes made it easy t' ensure correct fin alignment but the fins were attached one at a time, me bucko, aligned and allowed t' dry t' ensure all o' t' fins were attached correctly. Arrr! Avast, me proud beauty! T' two launch lugs were then glued on t' inside o' t' smaller tubes next t' t' main body tube, shiver me timbers, makin' sure they were nay in line with any o' t' fins at t' top.

Pic Pic

FinishedOnce complete this gave a very sturdy rocket but looked a bit bare towards t' top as t' main focus o' t' rocket was t' base. Ahoy! T' add more detail another 6 fins were cut from balsa t' match t' pattern round the base. These were two different shapes and were glued ½” from t' top o' t' body tube in line with t' tubes around t' base, again in an alternatin' fashion. Avast! Begad! T' help align t' smaller fins, me bucko, a line be drawn up from where the gap betwixt each o' t' smaller tubes was and then each fin glued separately.

At this stage t' nosecone was then sprayed silver and t' main body red, t' fins were protected with masking tape durin' sprayin' then t' balsa fins painted yellow and t' plastic fins painted black, me bucko, t' fins at t' top were painted t' match t' colour o' t' larger fins below them.

T' parachute be then constructed from t' plastic sheet by strengthenin' each o' t' six corners with a piece of sticky label and then piercin' holes in them. Arrr! Shroud line was then passed through each hole and stuck down with more sticky label. Each piece o' shroud line passed through two adjacent holes and t' loops were then collected at t' base where they were glued together. Ya scallywag! Avast, me proud beauty! T' elastic was then glued t' a folded piece o' card and glued into t' main body tube. T' shroud lines were then tied onto t' elastic and t' elastic tied onto t' nose cone connector.

With t' rocket finished I checked t' paint work and touched up t' fins, Zodiac was ready t' fly.

Flight:
My rocket was designed for a D motor however this was probably nay t' best idea as t' weight o' t' rocket be low enough for a B t' be sufficient. Ya scallywag! Well, blow me down! However with a small parachute I hoped recovery wouldn’t be too difficult.

T' first flight was in what seemed reasonably still conditions and Zodiac flew perfectly off t' pad on a D12-7, however, half way through flight a huge gust o' wind took Zodiac from its straight flight and sent it at an angle. The parachute still deployed at apogee but t' rocket was already away from t' launch site. Blimey! Well, blow me down! T' rocket then drifted into a bunch o' trees where it got stuck at t' top o' a tree, me bucko, just out o' reach. Aye aye! Unfortunately it could nay be flown again. Avast, me proud beauty!

Summary:
T' build itself went fantastically and t' flight o' t' rocket be spot on, however on a D motor t' rocket is just too light and unless you have a very large area t' fly it is quite likely that t' rocket will be unrecoverable even on a small parachute. Begad!

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