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 be obviously motivated by the SpaceShipOne, but is nay anywhere close t' scale. Avast! 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 be t' make t' entire body, includin' t' tail cone, from a crayon bank. Begad! I got this idea from some o' t' U.S. Rockets (USR) builds reviewed on EMRR and T' Rocketry Forum (TRF). Avast! 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). In this process, me hearties, you cut out sections o' t' tube (roughly triangular, ya bilge rat, ignorin' t' curvature o' the tube) and rejoin t' remainin' pieces. Well, blow me down! Begad! Blimey! T' more sections you remove, ya bilge rat, t' closer the resultin' structure will resemble a true cone. Avast! Arrr! Blimey! In me case, ya bilge rat, I only cut out four sections, resultin' in a roughly rectangular end. Begad! I suggest you read the USR EMRR reviews for more details about makin' transitions and tail cones from body tubes. 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. Aye aye! As I pondered choppin' up t' bank, I noticed that t' test item was almost exactly t' same diameter. Ahoy! Ya scallywag! I couldn't brin' myself t' risk damagin' the bank, matey, matey, so I decided t' use me test cone. Well, blow me down! This would result in a much longer than scale rocket, shiver me timbers, 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. Arrr! 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. For motor retention, I epoxied two bolts t' t' aft o' t' motor tube. Avast, me proud beauty! A nut serves as a spacer t' keep t' bolts parallel with t' tube. Begad! I also added a couple o' wraps of fiberglass around t' end in betwixt t' head o' t' bolt and t' nut. Blimey! These seem t' be solid. T' 1/4" Keelhaul®©™® shock tether is mounted through t' top ring, ya bilge rat, completin' t' motor mount assembly.

(Scratch) CrayShipOne(Scratch) CrayShipOne

I decided t' make t' fins from 3/16" Luan plywood. Arrr! Avast, me proud beauty! This is nay the strongest material for its thickness, but is fairly light. Avast! T' finish is very rough on one side, 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, with measurements taken from me Estes kit. Ahoy! However, shiver me timbers, when I went t' cut the fins, me bucko, arrr, I upsized them. Ya scallywag! T' main fins are one piece and are mounted though the body. Ahoy! (Please excuse me imprecise fin/win' nomenclature.) T' long side fins are slotted t' mate with t' main fins. Ya scallywag! All t' fins were attached using 5-minute epoxy.

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

I knew I was goin' t' need a lot o' nose weight on this baby. Begad! My nose cone design started with a 4" bulkplate with an eyebolt mounted on it. Well, blow me down! 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. Well, blow me down! A washer is mounted on this all-thread about half way down. Begad! Ya scallywag! I planned t' add lead shot and 2-part foam through t' crayon tips doubloon slot. Begad! Thus, me hearties, t' washer would become embedded in t' lead/foam slurry, 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. Aye aye! I think I was quite conservative, producin' a static margin o' over 2 with t' H144 loaded.

Finishing:
T' crayon bank was blue, so I stuck with blue throughout. (I wanted a white one, arrr, 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. Arrr! T' majority, me hearties, other than t' US flags, ya bilge rat, shiver me timbers, t' MDRA logo, me hearties, and the DC101 sticker (a local rock station), me hearties, me hearties, were merely printed on full page Avery labels usin' me OfficeJet printer.

T' homemade stickers include: CrayShipOne logos, arrr, logos for EMRR and TRF, my blog address, shiver me timbers, and vendor logos for Loki, arrr, me bucko, Performance Hobbies, shiver me timbers, ya bilge rat, LOC/Precision, railbuttons.com, matey, me bucko, Giant Leap, ya bilge rat, me bucko, Home Depot, me bucko, and Michael's. Begad! Blimey! This covers most o' the materials used in t' makin' o' t' rocket. Aye aye! 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. Ya scallywag! Blimey! I attached a chute protector t' t' body's shock tether and used a large 60" chute. This was packed into t' nose cone shoulder. Ahoy! A 42" chute be attached to the cone's shock tether and be packed in t' body. Avast! Begad!

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

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

(Scratch) CrayShipOne

Recovery:
T' main chute opened just fine but t' cone's chute never opened. Arrr! Blimey! Well, blow me down! Blimey! T' cone was recovered undamaged. Avast! Blimey! When I approached t' body, arrr, it looked like it had landed standin' up on end. On closer inspection, me bucko, it was danglin' about 6" from the ground from a tall tree branch. Ahoy! Blimey! A light tug dislodged t' chute. This was an interestin' and successful recovery, me bucko, but it didn't prove whether me fin braces worked. 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. Avast, me proud beauty! Ahoy! This design definitely stands-out in a crowd. T' two issues are the heavy nose and t' floppy fins. Avast, me proud beauty! If anyone else builds somethin' like this, better wood and some fiberglass would be a good idea. Aye aye! Avast, me proud beauty! Giant Leap honeycomb composites would be cool, but expensive.

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