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. Blimey! 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. Ahoy! T' Mini-V2 is a simple model and was constructed usin' "scrap" materials layin' around from other projects. Begad!

Image

Construction:
Materials used:

  1. Two PNC-50 nose cones (2.75" long), arrr, arrr, me bucko, one is used for t' tail cone
  2. BT-50 (4")
  3. BT-5 (~2 ¼")
  4. Used engine casings for centerin' rin' (24mm, me hearties, 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, ya bilge rat, and needs no elaboration. Avast! Begad! I used yellow glue for t' paper-paper joints and epoxy for the paper-plastic joints. Avast!

Tail cone assembly: Insert t' tip o' one cone into t' BT-5 tubing and mark. Well, blow me down! Cut t' end o' t' cone off (~1 3/16") so that t' BT-5 tube will just fit. Also, matey, cut off t' end o' t' nose cone immediately before the shock cord attachment. Usin' ½" sections o' t' 24mm and 18mm casings, make a rin' t' center t' BT-5 in t' nose cone shoulder. Aye aye! Blimey! This requires some peelin' and, o' course, me bucko, arrr, other materials can be used. Well, blow me down! 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. Begad! 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). Glue it all together.

Fins: Make a template usin' t' attached diagram. Aye aye! 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. Ahoy! Most any scrap balsa can be used, but I used 1/8". Avast, me proud beauty! Make sure t' grain is parallel t' the leadin' edge, ya bilge rat, etc. Begad! Begad! Holdin' sandpaper on t' boat tail, me bucko, arrr, sand t' root o' each fin so it conforms t' its curve. Ya scallywag! Avast, me bucko, me proud beauty! Glue t' fins on such that they overlap t' BT by ¼". Ya scallywag!

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. Avast, me proud beauty! Blimey!

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

Summary:
PROs: 1) Easy t' build, arrr, 2) Looks nice, 3) Gets positive comments from other fliers. Ahoy! CON: 1) Nay 100% scale.

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