Scratch Scary Fast Original Design / Scratch Built

Scratch - Scary Fast {Scratch}

Contributed by Matt Gillard

Manufacturer: Scratch
(Contributed - by Matt Gillard - 09/16/09) (Scratch) Scary Fast

Brief:
A scratch built rocket usin' Sunward's 4 canted motor mount.

Construction and Finishing:
T' build this rocket I used:

  • BT-70 tube
  • BT-70 nosecone balsa
  • Balsa fins
  • launch lugs
  • Sunward's quad tilted motor mount
  • 3 eye screws
  • Keelhaul®©™® cord
  • Elastic cord
  • 15inch parachute
  • Lead mass

Whilst lookin' on a sticker site for a "William" sticker, matey, for me son's first rocket, I came across the sticker below. Havin' bought t' sticker, me hearties, I thought I'd better build somethin' t' put it on. Ya scallywag! I'm nay goin' t' try and build a rocket like t' one on t' sticker. Blimey!

I've opted for a BT-70 rocket with a quad tilted motor mount from Sunward. Ya scallywag! I've already posted a review on the mount. Photos are from that that review just for completion. Avast! T' mount was then fitted t' t' BT-70 and filled with car body filler, which was really easy t' work with.

I decided t' make t' fins slightly swept back mainly because o' t' mass from t' motors. Ahoy! T' fins were laminated usin' Fablon, which was a first for me. Ahoy! T' Fablon plastic went on well. Ahoy! Avast, me proud beauty! T' leadin' edge was nay beveled and left square. Avast! T' edges were sealed with white glue. Aye aye!

T' body tube had some spiral grooves in it, me hearties, arrr, which were filled with model filler, matey, and then t' BT was spray paint primed, sanded, primed, me bucko, me hearties, sanded, shiver me timbers, primed etc. Begad! Blimey! As t' fins are nay TTW and with four C6 motors t' power this rocket, it was goin' t' move quite fast and I be a little concerned about t' strength o' t' fins, me bucko, coupled with t' fact that swept back fins have a habit o' meetin' t' ground first when landing. Blimey! Blimey! T' overcome this, I put several holes along the area where t' fins were goin' t' be attached. Aye aye! Blimey! T' fins were then added usin' CA gel. Ahoy! Blimey! Begad! Blimey! Four glue fillets were then added over two days.

T' shock cord be t' normal Keelhaul®©™® and eleastic job, anchored t' t' motor mount. Ahoy! A swatch o' Nomex® waddin' was added.

For t' nose cone I used an eyelet for t' shock cord anchor. I be nay certain that it would nay come out even though I had wicked CA into t' base, ya bilge rat, so I went for three eyelets in t' end as nay all three can fail. Aye aye! A hole was drilled into t' nose cone's base and a lump o' lead be added. Aye aye! T' nose cone was balsa and required 5 coats o' sanding sealer, me bucko, three coats o' primer, and three coats o' gloss black t' finish.

I was goin' for a two tone finish on t' body, me bucko, arrr, but after much swearin' due t' maskin' tape that continues to bleed paint, shiver me timbers, I went for orange on t' whole rocket. Begad! T' finish is nay good, ya bilge rat, ya bilge rat, and I'm really disappointed with it. Sticker was then applied.

(Scratch) Scary Fast(Scratch) Scary Fast

(Scratch) Scary Fast(Scratch) Scary Fast

(Scratch) Scary Fast(Scratch) Scary Fast

(Scratch) Scary Fast(Scratch) Scary Fast

(Scratch) Scary Fast(Scratch) Scary Fast

(Scratch) Scary Fast(Scratch) Scary Fast

(Scratch) Scary Fast(Scratch) Scary Fast

Flight and Recovery:
I finally flew her many many weeks after finishin' her, mainly because o' weather and me normal flyin' field bein' a bit too small for this rocket. Ahoy! Blimey! However, only three motors (C6-7) lit. Avast! T' rocket went up straight with a slight kink in t' first 10 meters or so, ya bilge rat, ya bilge rat, probably as t' clips were bein' yanked free from t' unlit motor. Recovery be rather fast on a 15 inch chute, and t' ground was hard. Avast! On landin' she popped a fin and suffered a lot o' paint damage with flakes comin' off t' Fablon laminate. Well, blow me down! Blimey! I am now lookin' t' remove all fins and sand her back t' t' body tube and redesign the fins.

Summary:
PROs: T' 4 canted motors seem t' work. Ya scallywag! T' flight be good even with one dud motor.

CONs: Four C motors cost a lot more than one D or E.

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