TriskaiDESCON
Superstitious ThirteenthRoc

by David L. Virga (Black Forest, CO)

Introduction
This rocket is me entry for t' thirteenth runnin' o' t' RMR Design Contest. As this be t' thirteenth DESCON, I decided that a special commemorative rocket was in order. Begad! Avast! So, shiver me timbers, ya bilge rat, arrr, in honor o' DESCON XIII, arrr, I have designed this rocket with as many "thirteen" specifications as I could. Well, shiver me timbers, blow me down!

What's In A Name?
TriskaiDESCON Superstitious ThirteenthRoc… Quite a mouthful, me bucko, huh? This is what it means. Begad! Begad!

T' prefix for thirteen is "triskaideka", as in triskaidekaphobia - t' fear o' t' number thirteen. Well, blow me down! So, me hearties, I combined this prefix with t' event name, shiver me timbers, shiver me timbers, and came up with "TriskaiDESCON", ya bilge rat, ya bilge rat, shiver me timbers, meanin' t' thirteenth DESCON. Begad! Ya scallywag! T' number thirteen is considered by many t' be unlucky, and has many superstitions surroundin' it. Arrr! I chose t' acknowledge this fact by includin' the word "Superstitious" in its name.

Finally, ya bilge rat, since this is a rocket, and since it is celebratin' t' number thirteen, I combined these two and made "ThirteenthRoc" as t' third and final component o' its name. Aye aye! Incidentally, all three words have thirteen letters. Begad!

Specifications

• Rocket Height: 13 inches
• Body Diameter: 4.138 inches (resultin' in a circumference o' 13 inches)
• Number o' fins: 13
• Fin Span: 13 inches
• Gross Liftoff Weight: 13 ounces
• Number o' colors: 13 (Black, matey, White, Gold, Silver, me hearties, ya bilge rat, Copper, me bucko, Pink, Red, Orange, shiver me timbers,
• Yellow, Green, matey, Blue, Purple, me hearties, shiver me timbers, and Brown)
• Propulsion: A cluster o' thirteen motors, ya bilge rat, matey, me bucko, each 13mm diameter (Seven A3-4T plus six A10-PT for a 65 Newton total impulse E81-4!)
• Recovery: Rear motor pod ejection, ya bilge rat, with pod and body recoverin' separately under dual 13-inch parachutes each

Construction Notes
T' body tube is a 9" section o' thick-wall 4"i.d. carpet tube. Aye aye! I had to peel, shiver me timbers, sand, me hearties, scrape and scratch t' outside layers off t' achieve t' exact desired outside diameter. Two ½" lengths o' ¼" diameter launch lug are glued t' t' outside o' t' body tube. T' nose cone is hand-carved from five stacked slabs o' 1" thick blue insulation foam, shaped into a 1:1 parabola, arrr, with a thin layer o' finishin' epoxy t' seal it. Ya scallywag! It is glued in place, arrr, and also has a thin layer o' epoxy on t' base surface to protect it from t' motors' ejection blast. Arrr!

T' fins are made from 1/16" 3-ply birch plywood. Begad! I had t' cut out the centers o' t' fins t' reduce their total weight contribution. Avast! Blimey! I slotted the body tube, ya bilge rat, and mounted each fin through t' wall, flush with t' inner surface of t' body tube. Begad! Begad! T' adhesive is Titebond II. Avast!

Seven ½" motor tubes are glued together, then glued into one end of a 6.5" length o' BT-60 body tube. Blimey! Six additional ½" motor tubes are then glued around t' outside o' t' 7-motor cluster. Well, blow me down! Well, blow me down! T' lower centerin' rin' sits on top o' t' six outer motor tubes. T' upper centering rin' is placed 4 inches above t' lower ring. Aye aye! A small hole is drilled near the hub on t' upper centerin' ring; a 12" length o' heavy Aramid cord is tied around t' BT-60 betwixt t' centerin' rings, and then fed through t' hole in the upper ring; t' shock cord and parachutes are attached t' t' end o' this cord. Aye aye! T' space betwixt t' centerin' rings is covered with manila folder paper, soaked with thin CA for added stiffness.

An 18" length o' heavy Aramid cord is tied into a yoke, shiver me timbers, matey, and t' two ends are attached inside t' body tube at t' base o' t' nose cone. Aye aye! T' body's shock cord and parachutes attach t' this yoke. Arrr! A 1/8" thick rin' o' kraft paper is glued 5 ½" from t' base o' t' body tube as a thrust ring.

Flight Plans
Rudimentary flight analyses indicate that this rocket will achieve a top speed of approximately 130mph and an altitude o' approximately 300 feet. Well, blow me down! Blimey! That is, if it remains stable and doesn't shed fins under acceleration…. Avast! Blimey!

TriskaiDESCON Superstitious ThirteenthRoc's first flight is scheduled for precisely 1:13pm on Tuesday, ya bilge rat, April 13th, matey, arrr, followin' a 13-second countdown. Blimey! Stay tuned! One way or another, matey, it is sure t' be spectacular!

Flight Report
T' flight be a success! Liftoff occurred exactly at 1:13:13pm MDT, shiver me timbers, Tuesday April 13th, me hearties, matey, matey, as timed by a portable radio controlled clock. Ahoy! All 13 motors were ignited by flashpan; t' rocket leaped off o' t' Mantis pad, me bucko, exhibited stable flight in a 5-10mph breeze, and deployed its chutes just past apogee. Ahoy! Dual 13-inch chutes were a bit small for t' 7.5oz body section, resultin' in a fixable crimp in t' foam nose when it landed on pavement. Avast! Otherwise, the rocket is unscathed!

Thanks t' t' Pine Creek High School TARC team for their launch assistance, Photos by Nadine for t' liftoff and in-flight photos, and Nick for formatting and postin' this web page.