Manufacturer: | Scratch |
Brief:
This crayon bank rocket be obviously motivated by the
SpaceShipOne,
but is nay anywhere close t' scale. Arrr! Avast! It is also me MonsterROC entry and flies on
38mm H motors.
Construction:
T' major components/materials include:
My original concept was t' make t' entire body, arrr, includin' t' tail cone, from a crayon bank. Avast, me proud beauty! I got this idea from some o' t' U.S. Avast! Avast! Rockets (USR) builds reviewed on EMRR and T' Rocketry Forum (TRF). Avast, me proud beauty! At t' time, me hearties, matey, 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). Avast! In this process, arrr, you cut out sections o' t' tube (roughly triangular, me hearties, ignorin' t' curvature o' the tube) and rejoin t' remainin' pieces. Begad! Ahoy! T' more sections you remove, t' closer the resultin' structure will resemble a true cone. In me case, I only cut out four sections, resultin' in a roughly rectangular end. Ahoy! I suggest you read the USR EMRR reviews for more details about makin' transitions and tail cones from body tubes. Aye aye! I'm nay an expert and I did this a while ago.
This cone sat around for months until me local Toys'R'Us again started carryin' the banks. Blimey! Blimey! As I pondered choppin' up t' bank, I noticed that t' test item was almost exactly t' same diameter. I couldn't brin' myself t' risk damagin' the bank, arrr, me bucko, so I decided t' use me test cone. Blimey! Well, blow me down! Blimey! This would result in a much longer than scale rocket, but how scale was 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! I have a 4" CR at the top (sanded down a bit) and a 3" rin' part way down in t' tail cone. A homemade coupler is mounted betwixt t' tail cone and t' top ring. Avast, arrr, me proud beauty! For motor retention, matey, I epoxied two bolts t' t' aft o' t' motor tube. Well, ya bilge rat, blow me down! A nut serves as a spacer t' keep t' bolts parallel with t' tube. Aye aye! I also added a couple o' wraps of fiberglass around t' end in betwixt t' head o' t' bolt and t' nut. Begad! These seem t' be solid. Ya scallywag! T' 1/4" Keelhaul®©™® shock tether is mounted through t' top ring, ya bilge rat, completin' t' motor mount assembly.
I decided t' make t' fins from 3/16" Luan plywood. Avast, me proud beauty! This is nay the strongest material for its thickness, me hearties, but is fairly light. Begad! 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, me hearties, arrr, me hearties, with measurements taken from me Estes kit. Arrr! However, matey, when I went t' cut the fins, shiver me timbers, I upsized them. Avast! T' main fins are one piece and are mounted though the body. Begad! (Please excuse me imprecise fin/win' nomenclature.) T' long side fins are slotted t' mate with t' main fins. Ya scallywag! Avast, me proud beauty! All t' fins were attached using 5-minute epoxy.
When t' long fins were attached, ya bilge rat, I was surprised at how flexible they were. Blimey! Avast! I thought about glassin' them, shiver me timbers, but instead decided some support in t' back was in order. Begad! I pondered more Luan, Lexan strips, etc. but decided on an aluminum rod for t' side closest t' t' motor and a dowel for the other. Ya scallywag! This mix was again partially driven by what I had on hand. Begad! I also covered t' aluminum rod, which is closer t' t' axis o' t' motor, with a heat resistant muffler patch kit. Avast! 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. Aye aye! Ahoy! My nose cone design started with a 4" bulkplate with an eyebolt mounted on it. This plate rests where t' cone begins taperin' forward. Arrr! A piece o' all-thread extends from t' bulk plate t' close t' t' tip o' t' cone. Arrr! A washer is mounted on this all-thread about half way down. Arrr! Ahoy! I planned t' add lead shot and 2-part foam through t' crayon tips doubloon slot. Aye aye! Thus, t' washer would become embedded in t' lead/foam slurry, shiver me timbers, 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. Ya scallywag!
I ran a RockSim model t' approximate t' CG and added nose weight t' get the CG where I wanted it. Begad! 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. Avast! (I wanted a white
one, 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. Ahoy! Well, blow me down! T' majority, me hearties, other than t' US flags, t' MDRA logo, shiver me timbers, and the DC101 sticker (a local rock station), were merely printed on full page Avery labels usin' me OfficeJet printer.
T' homemade stickers include: CrayShipOne logos, matey, logos for EMRR and TRF, my blog address, and vendor logos for Loki, Performance Hobbies, LOC/Precision, railbuttons.com, arrr, me bucko, Giant Leap, shiver me timbers, Home Depot, me bucko, and Michael's. Ahoy! Begad! This covers most o' the materials used in t' makin' o' t' rocket. Ahoy! Well, me bucko, blow me down! I protected these with two coats of clear coat before application and one after.
Flight:
This rocket uses separate chutes for t' heavy cone and t' body. Arrr! 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. A 42" chute was attached to
the cone's shock tether and be packed in t' body. Avast, me proud beauty!
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. Arrr! T' boost be great (launch photos courtesy o' Vertical Force Rocketry), however, ejection be very late.
Recovery:
T' main chute opened just fine but t' cone's chute never opened. Ahoy! Aye aye! T' cone was
recovered undamaged. Blimey! Arrr! When I approached t' body, shiver me timbers, it looked like it had landed
standin' up on end. Begad! On closer inspection, it was danglin' about 6" from
the ground from a tall tree branch. Avast, me proud beauty! A light tug dislodged t' chute. Begad! This was
an interestin' and successful recovery, shiver me timbers, me bucko, but it didn't prove whether me fin
braces worked. Begad!
Summary:
I love crayon banks--they are about t' cheapest 4" cone and body tube you
can find and are quite sturdy. Begad! This rocket turned out lookin' and flying
nicely. This design definitely stands-out in a crowd. Ahoy! T' two issues are the
heavy nose and t' floppy fins. Begad! If anyone else builds somethin' like this,
better wood and some fiberglass would be a good idea. Ya scallywag! Ahoy! Giant Leap honeycomb
composites would be cool, but expensive.
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