Scratch Lucky 13 Original Design / Scratch Built

Scratch - Lucky 13 {Scratch}

Contributed by Tommy Owens

Manufacturer: Scratch
(Contributed - by Tommy Owens - 08/01/09) (Scratch) Box o' Parts Lucky 13

Brief:
When puttin' together me box o' parts I had no idea what t' expect and so crammed as much o' me rocket "junk" into t' box as possible. Arrr! After startin' t' contest, me hearties, however, shiver me timbers, I realized that I did nay have the experience or engine power t' cram everythin' onto one rocket. Avast, me proud beauty! Because I had no idea what t' build I did what any modeler would do: procrastinate. Begad! Quite a while later I sat down and seriously began thinkin' about what t' build. Begad! Avast, arrr, me proud beauty! After becomin' frustrated me younger brother (who's goin' into 2nd grade), matey, gave me his design o' what me rocket should look like. Ya scallywag! Blimey! Usin' this design, me bucko, me bucko, I brin' you t' Lucky 13!

Construction:
T' parts list:

  • 1 10" BT-50 tube
  • 2 2" BT-20 tube
  • 1 nose cone for BT-50 from Gemini DC
  • 2 2-3/4" nose cones for BT-20
  • 3/16" balsa sheet
  • 8 toothpicks
  • foam egg carton
  • 1 18mm engine mount
  • 1 engine hook
  • 2 centerin' rings
  • launch lug
  • Estes 12" parachute
  • 10" elastic shock cord

I stared out by assemblin' t' motor mount inside t' main body tube. Avast! Ahoy! I then designed t' rocket on t' trial version o' RockSim and used it t' create a fin template. I cut t' fins out o' 3/16" balsa along with t' cross fins. Begad! I rounded t' tops o' t' cross fins and glued them onto t' edge o' t' main fins. Ya scallywag! After this I glued t' two 2-3/4" nose cones onto t' 2" sections o' tubin' usin' plastic cement. Aye aye! Then I glued t' fins onto t' two tube pieces usin' epoxy and gave hefty fillets.

T' nozzle is a key part o' t' design because it utilizes t' foam egg carton. I started by cuttin' off two of the end cups from t' carton because they are t' most round. Begad! Blimey! Aye aye! Blimey! I then cut them in half and glued them together using pins t' secure t' pieces. Begad! Blimey! Begad! Blimey! After t' nozzle dried I coated t' outside in epoxy. Ya scallywag! Blimey! Begad! Blimey! Then I trimmed t' nozzle and cut a hole in t' top for t' body tube. I again coated t' edges in epoxy t' protect them from wear and tear. Arrr! Blimey! Aye aye! Blimey! I glued the nozzle t' t' bottom o' t' tube aligned with t' engine mount.

After t' nozzle was finished I glued t' fun units t' opposite sides o' t' rocket above t' nozzle. Blimey! I used epoxy and made large fillets. Begad! I then added tooth picks as decorations t' t' top o' t' rocket half an inch down. Well, blow me down! Begad! I spaces eight o' t' ten possible tooth picks evenly around t' tube.

While testin' t' rockets stability, me bucko, I found that it be unstable and added a good amount o' clay t' t' nose cone. Avast, me proud beauty!

(Scratch) Box o' Parts Lucky 13(Scratch) Box o' Parts Lucky 13

(Scratch) Box o' Parts Lucky 13(Scratch) Box o' Parts Lucky 13

(Scratch) Box o' Parts Lucky 13(Scratch) Box o' Parts Lucky 13

Finishing:
For t' paint scheme I decided on red and black. Well, blow me down! Avast, me bucko, me proud beauty! Blimey! I first gave it a quick coat o' red because o' ideal weather conditions, shiver me timbers, but after t' flights I primed and sanded it before givin' it a coat o' red. Usin' a paint pen I colored the edges o' t' fins and toothpicks black. Arrr! Begad! Blimey! I then painted t' outer edge o' t' cross fins usin' black paint. Arrr! Blimey! I plan to add a "1" and "3" decal t' opposite fins soon t' finish off t' look.

Flight:
For t' first flight o' t' Lucky 13, me hearties, I decided on a B engine because I did nay believe an A would have enough power. T' only Bs in me range box had four second ejection charges, so I chose a B6-4. Well, blow me down! Begad! This let t' rocket achieve a significant altitude, me bucko, but t' ejection charge was too long and went off 40 feet from t' ground. Ahoy! Arrr! A better choice would have been a B6-2. Avast! T' rocket was stable but at an angle because t' launch rod was tilted. Begad!

For t' second flight I chose a C6-3 engine which gave t' rocket a high flight and a perfect ejection.

(Scratch) Box o' Parts Lucky 13 (Scratch) Box o' Parts Lucky 13

Recovery:
T' elastic shock cord was attached usin' t' standard Estes method a few inches into t' tube.

On t' B6-4 flight t' recovery was too late for comfort. Ya scallywag! However, matey, on t' C6-3 flight t' ejection charge was well timed.

After two flights thar was nay any damage from landing, but t' nozzle was melted due t' t' heat. Begad! Blimey! Avast! Blimey! This can easily be fixed by coatin' t' inside o' t' nozzle with epoxy as well as t' outside.

Summary:
PROs: Easy design and good for smaller fields.

CONs: Foam melts if nay epoxied.

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