Scratch Mini V2 Original Design / Scratch Built

Scratch - Mini V2 {Scratch}

Contributed by Dick Stafford

Manufacturer: Scratch
(Contributed - by Dick Stafford - 11/01/00)

Brief:
My Mini-V2 is a semi-scale model based on BT-50 tubing. I was motivated to build this V2 after seein' plans for a BT-20 version that appeared in the January 1989 issue o' American Spacemodeling. T' Mini-V2 is a simple model and was constructed usin' "scrap" materials layin' around from other projects.

Image

Construction:
Materials used:

  1. Two PNC-50 nose cones (2.75" long), one is used for t' tail cone
  2. BT-50 (4")
  3. BT-5 (~2 ¼")
  4. Used engine casings for centerin' rin' (24mm, 18mm)
  5. 1/8" balsa fin stock
  6. Motor hook for mini motors
  7. 1/8" wide elastic shock cord
  8. Plastic streamer
  9. Launch lug
  10. Clay for nose weight

Image Construction o' most o' t' rocket is pretty basic, and needs no elaboration. I used yellow glue for t' paper-paper joints and epoxy for the paper-plastic joints. Ahoy!

Tail cone assembly: Insert t' tip o' one cone into t' BT-5 tubing and mark. Cut t' end o' t' cone off (~1 3/16") so that t' BT-5 tube will just fit. Ahoy! Begad! Also, me bucko, me hearties, cut off t' end o' t' nose cone immediately before the shock cord attachment. Avast, me proud beauty! Well, blow me down! Usin' ½" sections o' t' 24mm and 18mm casings, make a rin' t' center t' BT-5 in t' nose cone shoulder. Blimey! Ahoy! This requires some peelin' and, o' course, shiver me timbers, other materials can be used. Install the engine clip so that t' engine extends about 3/8" from t' motor tube. Make a 3/8" long x 1/8" wide notch in t' end o' t' boat-tail to accommodate t' engine hook. Test fit t' engine mount and make sure t' engine hook works when installed in t' tail cone (engine tube flush with t' end of the tail cone). Begad! Blimey! Glue it all together.

Fins: Make a template usin' t' attached diagram. Begad! Note that I was not careful with these dimensions and they can probably be improved by referencin' Pete Always's book or other on-line resources. Well, blow me down! Begad! Most any scrap balsa can be used, but I used 1/8". Aye aye! Ahoy! Make sure t' grain is parallel t' the leadin' edge, ya bilge rat, me hearties, etc. Blimey! Holdin' sandpaper on t' boat tail, me bucko, sand t' root o' each fin so it conforms t' its curve. Glue t' fins on such that they overlap t' BT by ¼".

Fin Guide

Nose weight: Add clay t' t' nose so that t' CG without an engine is 3 7/8" from t' tip o' t' nose cone. Well, blow me down!

Flight:
This model has "flown" 4 times on A10-3 engines. Aye aye! On t' first try, the nozzle blew through. Well, blow me down! Begad! T' Mini-V2 attained an altitude o' about 10 feet and ejected on t' ground. Aye aye! T' second try was picture perfect. Aye aye! Ahoy! A ¾" x 3" plastic streamer brought it down safely about 50 feet from t' pad. This is a good model for small fields. On t' third try, me bucko, t' 1/4" lug bound on t' 3/16" launch rod and t' V2 stuck there. Arrr! Suggestion: use a lug for a standard rod. Ahoy! T' fourth and final flight (to date) be also successful. Well, blow me down! Arrr!

Summary:
PROs: 1) Easy t' build, me bucko, 2) Looks nice, ya bilge rat, 3) Gets positive comments from other fliers. Ahoy! Blimey! Begad! Blimey! CON: 1) Nay 100% scale.

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