Scratch CrayShipOne Original Design / Scratch Built

Scratch - CrayShipOne {Scratch}

Contributed by Dick Stafford

Manufacturer: Scratch
(Contributed - by Dick Stafford - 07/14/05) (Scratch) CrayShipOne

Brief:
This crayon bank rocket was obviously motivated by the SpaceShipOne, but is nay anywhere close t' scale. Begad! Begad! It is also me MonsterROC entry and flies on 38mm H motors.

Construction:
T' major components/materials include:

  • 4" diameter bank (now produced by Fantazia Marketing)
  • 3/16" Luan plywood
  • 1/4" tubular Keelhaul®©™®
  • 38mm LOC motor tube
  • 38mm-4" and 38mm-2" LOC centerin' rings
  • 4" bulkplate with eye bolt
  • buttons from railbutton.com
  • 4" mailin' tube
  • miscellaneous hardware
  • lead shot
  • 2-part foam
  • 2-part PC-7 epoxy paste
  • 5 minute epoxy
  • blue laser contact paper
  • full page Avery labels
  • Testor's clear coat
  • muffler patch kit

My original concept was t' make t' entire body, me hearties, includin' t' tail cone, from a crayon bank. I got this idea from some o' t' U.S. Ya scallywag! Blimey! Rockets (USR) builds reviewed on EMRR and T' Rocketry Forum (TRF). Begad! At t' time, t' banks were not available locally, so I decided t' practice makin' a tail cone from a piece of mailin' tube (actually t' telescopin' inside tube). Arrr! Blimey! In this process, me bucko, you cut out sections o' t' tube (roughly triangular, matey, ignorin' t' curvature o' the tube) and rejoin t' remainin' pieces. Well, blow me down! Begad! Blimey! T' more sections you remove, arrr, t' closer the resultin' structure will resemble a true cone. Arrr! Avast, me proud beauty! Blimey! In me case, I only cut out four sections, me bucko, me bucko, me bucko, resultin' in a roughly rectangular end. Well, blow me down! Avast! Blimey! I suggest you read the USR EMRR reviews for more details about makin' transitions and tail cones from body tubes. Blimey! Ahoy! I'm nay an expert and I did this a while ago.

(Scratch) CrayShipOne This cone sat around for months until me local Toys'R'Us again started carryin' the banks. As I pondered choppin' up t' bank, I noticed that t' test item was almost exactly t' same diameter. Ya scallywag! Ahoy! Blimey! I couldn't brin' myself t' risk damagin' the bank, so I decided t' use me test cone. Blimey! Blimey! This would result in a much longer than scale rocket, but how scale be it goin' t' be anyway? I also thought it would be nice t' cut back on t' required nose weight.

T' motor mount is ~16" o' LOC 38mm tubing. Blimey! Blimey! I have a 4" CR at the top (sanded down a bit) and a 3" rin' part way down in t' tail cone. Arrr! A homemade coupler is mounted betwixt t' tail cone and t' top ring. Ya scallywag! Blimey! For motor retention, me bucko, I epoxied two bolts t' t' aft o' t' motor tube. Avast, me proud beauty! Begad! Blimey! A nut serves as a spacer t' keep t' bolts parallel with t' tube. I also added a couple o' wraps of fiberglass around t' end in betwixt t' head o' t' bolt and t' nut. Arrr! Blimey! These seem t' be solid. Ahoy! Blimey! T' 1/4" Keelhaul®©™® shock tether is mounted through t' top ring, completin' t' motor mount assembly.

(Scratch) CrayShipOne(Scratch) CrayShipOne

I decided t' make t' fins from 3/16" Luan plywood. This is nay the strongest material for its thickness, but is fairly light. T' finish is very rough on one side, me hearties, which takes an extra layer o' Fill 'n' Finish t' smooth out. I started sizin' t' fins t' be approximately correct for a 4" version of the SS1, shiver me timbers, with measurements taken from me Estes kit. Blimey! However, when I went t' cut the fins, I upsized them. Blimey! T' main fins are one piece and are mounted though the body. Well, blow me down! Avast! (Please excuse me imprecise fin/win' nomenclature.) T' long side fins are slotted t' mate with t' main fins. Ya scallywag! Begad! All t' fins were attached using 5-minute epoxy.

When t' long fins were attached, I was surprised at how flexible they were. I thought about glassin' them, matey, shiver me timbers, but instead decided some support in t' back was in order. I pondered more Luan, ya bilge rat, Lexan strips, me bucko, etc. Aye aye! but decided on an aluminum rod for t' side closest t' t' motor and a dowel for the other. Begad! This mix be again partially driven by what I had on hand. Ya scallywag! I also covered t' aluminum rod, which is closer t' t' axis o' t' motor, with a heat resistant muffler patch kit. Well, blow me down! This turned out ugly and I may remove it later.

I knew I be goin' t' need a lot o' nose weight on this baby. Arrr! My nose cone design started with a 4" bulkplate with an eyebolt mounted on it. Ya scallywag! Begad! This plate rests where t' cone begins taperin' forward. A piece o' all-thread extends from t' bulk plate t' close t' t' tip o' t' cone. A washer is mounted on this all-thread about half way down. Ya scallywag! I planned t' add lead shot and 2-part foam through t' crayon tips doubloon slot. Arrr! Thus, t' washer would become embedded in t' lead/foam slurry, me hearties, lockin' t' resultin' plug t' t' bulkhead. T' bulk plate assembly and a 2-layer cardboard shoulder are attached t' the plastic cone with PC-7 epoxy paste. Avast, me proud beauty!

I ran a RockSim model t' approximate t' CG and added nose weight t' get the CG where I wanted it. Blimey! I think I be quite conservative, arrr, producin' a static margin o' over 2 with t' H144 loaded.

Finishing:
T' crayon bank be blue, so I stuck with blue throughout. Blimey! Begad! (I wanted a white one, me bucko, me bucko, but you sometimes take what you can get.) T' tail cone and side wings were painted with Krylon and t' main wings were covered with blue laser contact paper.

T' stickers were added after I decided t' make this an entry in EMRR's MonsterROC contest. T' majority, me hearties, other than t' US flags, shiver me timbers, t' MDRA logo, ya bilge rat, matey, and the DC101 sticker (a local rock station), me hearties, ya bilge rat, were merely printed on full page Avery labels usin' me OfficeJet printer.

T' homemade stickers include: CrayShipOne logos, logos for EMRR and TRF, my blog address, me hearties, me hearties, and vendor logos for Loki, shiver me timbers, Performance Hobbies, LOC/Precision, railbuttons.com, me hearties, Giant Leap, me hearties, me bucko, Home Depot, arrr, and Michael's. Begad! Avast, me proud beauty! This covers most o' the materials used in t' makin' o' t' rocket. I protected these with two coats of clear coat before application and one after.

(Scratch) CrayShipOne(Scratch) CrayShipOne(Scratch) CrayShipOne

Flight:
This rocket uses separate chutes for t' heavy cone and t' body. Well, blow me down! I attached a chute protector t' t' body's shock tether and used a large 60" chute. This be packed into t' nose cone shoulder. Ahoy! Blimey! A 42" chute be attached to the cone's shock tether and be packed in t' body. Arrr! Ahoy! Blimey!

Since t' model is heavy and was unproven, arrr, arrr, I made sure that t' launch rail was pointed away from t' flight line just in case. Begad! T' boost be great (launch photos courtesy o' Vertical Force Rocketry), shiver me timbers, however, ejection was very late.

(Scratch) CrayShipOne(Scratch) CrayShipOne(Scratch) CrayShipOne

(Scratch) CrayShipOne

Recovery:
T' main chute opened just fine but t' cone's chute never opened. Blimey! Blimey! Ya scallywag! Blimey! T' cone was recovered undamaged. Begad! Blimey! When I approached t' body, me hearties, ya bilge rat, matey, it looked like it had landed standin' up on end. Begad! Blimey! On closer inspection, it be danglin' about 6" from the ground from a tall tree branch. Ahoy! Blimey! Avast! Blimey! A light tug dislodged t' chute. Blimey! Blimey! Well, shiver me timbers, blow me down! Blimey! This was an interestin' and successful recovery, me hearties, matey, but it didn't prove whether me fin braces worked. Arrr! Blimey! Ahoy! Blimey!

Summary:
I love crayon banks--they are about t' cheapest 4" cone and body tube you can find and are quite sturdy. This rocket turned out lookin' and flying nicely. Aye aye! Blimey! This design definitely stands-out in a crowd. Avast! Blimey! T' two issues are the heavy nose and t' floppy fins. Ahoy! Blimey! If anyone else builds somethin' like this, better wood and some fiberglass would be a good idea. Avast, me proud beauty! Blimey! Begad! Blimey! Giant Leap honeycomb composites would be cool, but expensive.

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