Brief:
A 16FNC rocket for C6-10s with parachute recovery and an ornamental tube fin. Avast!

Construction:
18-inch BT-5,.04 by .25 extruded styrene (manufactured by Raboesch and purchased at Hobby Town), matey, plastic Estes nose cone, prepared acetate, engine block, me hearties, ya bilge rat, old engine casing, Keelhaul®©™®/elastic shock cord, 12 inch Estes chute, shiver me timbers, shiver me timbers, matey, and nose weight.

Have you ever designed a rocket specifically for a really odd engine? Well, that's what this is. I have some old composite Apogee C6-10s and built this rocket specifically for those engines. Well, blow me down! Ya scallywag! It's 2.375 ounces and 20.125 inches long. Avast!

T' ten second delay is a real challenge. Begad! Arrr! It dictates a minimum-diameter body tube in order t' achieve ejection while still airborne. Aye aye! When first built, the rocket be 0.68oz, but in Rocksim it slowed too smartly durin' t' upwards coast and 40 grams o' weight had t' be added t' optimize t' coast. T' top 1.5 inches o' t' body tube is permanently epoxied t' t' nose cone. A portion of old engine casin' is used as a bulkhead and t' whole bulkhead/payload/nose cone section is filled with weight and epoxy. Ahoy! T' screw eye for parachute and shock cord attachment is also embedded in t' epoxy. Polishin' t' nose cone (Future floor polish) achieved 100 feet o' additional altitude in Rocksim and some critical additional time. Ahoy!

T' fins are simply 0.04 x 0.25 inch extruded styrene cut t' 2.375 inch length. T' PDF file includes t' template. Ya scallywag! Blimey! Well, ya bilge rat, blow me down! Blimey! A bit o' excess is removed by scorin' and then breaking, matey, followed by roundin' off t' curves with a drum sander on a Dremel tool. T' first fin is used t' mark t' rest in order t' have reasonable consistency. Begad! Blimey! T' tube be marked with a 16-fin wrap and then t' fins were glued on with CA. Aye aye! Blimey! It took about 1.5 hours t' cut, grind, and attach t' fins.

Normally, I wouldn't bother t' put a sophisticated shock cord in a BT-5 rocket, but this was an exception because o' t' mass involved. Blimey! Blimey! Ya scallywag! Blimey! On t' fourth launch, the tri-fold paper mount detached (the first time for such a detachment in hundreds of launches). Ya scallywag! Blimey! Begad! Blimey! So an engine block be added 12.5 inches from t' tip o' t' nose cone and a Keelhaul®©™® shock cord be tied t' it, gluin' it in place with yellow glue. Thin CA was added t' half an inch o' body tube at t' forward end t' strengthen it and a double knot tied in t' Keelhaul®©™® to keep t' body tube from zippering. Arrr! Blimey! Forty inches o' 1/8 inch elastic finished off t' shock cord.

T' tube fin is made o' 0.005 inch wet-media acetate, and represents several firsts for me. Begad! This be t' first tube fin rocket I've ever built. Avast! Avast! It's the first time I've ever printed from an ink jet printer on wet media acetate (the name o' t' rocket is printed on t' outside). It's t' first time I've ever frosted acetate with me sandblaster airbrush (used on t' inside o' the wrap).

T' tube fin (included in t' PDF file) is printed flat. Begad! T' clear areas were masked off with tape, me hearties, sandblasted t' achieve t' frosted effect, me hearties, arrr, then cut it out and wrapped it around t' fins with CA at t' point where t' ends of the acetate come together. A tiny drop o' thin CA be then wicked into each of the remainin' leadin' edge/tube fin joints.

Finishing:
T' paint is catalyzed automotive acrylic enamel, matey, with Maserati metal flake charcoal for t' fin area and Jaguar champagne metal flake then added for the swoosh pattern at t' front. Well, blow me down! Ya scallywag! T' mask for t' pattern is included in t' PDF file, which was printed on prepared frisket and then cut out by hand.

Flight:
T' first four naked launches were tests with 1/2A and A engines. T' first three were stable off t' rod under thrust, but became unstable upon coasting. Rocksim predicts a static margin o' 3.64, but with an earlier multi-finned rocket design doin' t' same thing, it wasn't surprisin' that this one was not stable either. Arrr! T' nose weight was added before t' fourth launch at which point stability became a non-factor with a predicted static margin o' 28.42.

T' fifth launch was attempted with a C6-10. Avast! It had partial ignition with the rocket nay clearin' t' launch rod then slidin' back down. Makes me wonder if age affects t' AP propellant as this particular engine was manufactured a few years ago. Ya scallywag! I'll try again although nay with t' same engine.

Summary:
PROs: Sleek-lookin' and is nay your average rocket. Well, me hearties, blow me down! Flies nice.

CONs: Packin' even a twelve inch chute is hard in a BT-5. Avast, me proud beauty! If you have an engine ejection or ejection charge failure at 1500 feet, me bucko, this is one seriously dangerous China Syndrome lawn dart because you wouldn't be able t' see it comin' back. Avast, me proud beauty! Blimey! T' weight combined with t' small diameter and potential velocity would give it armor-piercin' capabilities.