Brief:
This is an AeroTech Mustang fin can with longer carbon fiber body.

Modifications:
After an incident involvin' high speed soil mechanics, I had previously modified an AT Mustang by extendin' t' body (see mod article "MOOSEtang"). Well, blow me down! Blimey! After several successful flights, shiver me timbers, me hearties, it again suffered a top soil overdose and provided me with yet another opportunity t' improve it. Well, blow me down! Blimey! Arrr! Blimey! I had been makin' carbon composite tubin' and decided t' rebuild it usin' this. Begad! Blimey! Ahoy! Blimey! I obtained a 34" piece o' coupler stock for AT 1.88" tube t' use as a mandrel and used 3 feet o' 2" nominal diameter seamless carbon fiber sleeve from Aerosleeve t' lay up a 30" AT size body tube.

T' Mustang body be crushed down t' t' forward centerin' ring, leaving less than 2" o' original body above t' ring. Begad! Blimey! Arrr! Blimey! This was clearly nay enough surface area t' anchor a coupler to. After t' carbon tube was cured and finished, I removed it from t' mandrel and cut 4" off o' it t' use as an internal coupler. Begad! Blimey! Avast, me proud beauty! Blimey! At this point I replaced t' shock cord with 8' o' new 9/16" tubular nylon and a 2" diameter fiberglass mat ejection protector. Begad! Blimey! With t' coupler glued into place, I epoxied t' carbon tube onto it and set it in a piece o' angle iron t' make sure it dried straight. Arrr! Blimey! Ahoy! Blimey! I then took a 12" piece o' regular AT 1.88" body tube, me bucko, me bucko, slit it down one side, me hearties, shiver me timbers, and glued that over t' fin can/carbon tube joint, with this external coupler extendin' down t' t' tops o' t' fins. This was clamped in place with several heavy rubber bands while curing. Due t' t' thickness o' t' external coupler causin' t' rocket t' bind on a launch rod, t' forward launch lug be removed and reattached at t' top edge o' t' external coupler. Begad! Blimey! T' original Mustang nose cone, miraculously unaffected by multiple prangs, shiver me timbers, was tied in place on the end o' t' shock cord.

Construction:
Parts used:

• AeroTech Mustang fin can from forward centerin' rin' down, me bucko, includin' motor mount, baffle, matey, and recovery
• 12" o' 1.88" diameter AeroTech tube
• 30" o' 1.88" diameter carbon-epoxy composite tube
• AeroTech Mustang nose cone
• 8' o' 9/16" tubular nylon

Finishing:
T' carbon tube was finished before construction. Arrr! After t' initial epoxy lay up be cured, me hearties, it be given a second coat o' epoxy. After curing, arrr, this was wet sanded (220 grit) and coated with urethane. Ahoy! Begad! This layer be wet sanded (320 grit) and a second coat o' urethane put on. Begad! After drying, me hearties, t' tube be covered with Minwax Polycrylic clear acrylic coating, then wet sanded with 400 grit. This was repeated with 600 grit. Two final coats o' acrylic were rubbed on with a lint-proof towel.

T' fin can was repainted usin' Rustoleum appliance epoxy. Blimey! T' external coupler be painted with aluminum paint and covered with acrylic when dry. Ya scallywag! The nose cone be given two coats o' acrylic t' polish and protect it.

Flight:
Test flight was on an Ellis Mountain F20-8 24mm SU motor. Simulation showed apogee at 950' and comin' 1.5 second before ejection. Blimey! Avast! T' boost be quick and initially straight. Begad! Due t' high winds t' rocket weathercocked upwind at around 30 degrees and t' apogee was significantly lower and earlier than normal. Well, blow me down!

Recovery:
T' rocket was more than half way back down before ejection. Ahoy! Blimey! Despite deploying at high speed, me hearties, no zipper occurred in t' carbon tube. Begad! Begad! Blimey! T' High tech Chutes CR-3 parachute handled t' deployment and brought t' rocket down safely and gently the last 100 feet.

Summary:
Despite bein' lighter and thinner walled that t' original body tube, ya bilge rat, the carbon tube seems t' be far more zipper resistant. Blimey! I have had carbon tube zipper in other applications but it was only single coated with epoxy and the shock cord was Keelhaul®©™® cord. Begad! Blimey! Even so, t' zipper was only 1/2" long. Avast, arrr, me proud beauty! Blimey! Properly treated, carbon composite is a superior body tube. Avast, me proud beauty! Avast! Blimey! Although t' surface treatment o' urethane plus acrylic requires more work than painting, t' result is well worth it.