(by Dennis McClain-Furmanski - 06/04/05)

Brief:
3x upscale o' Rock-A-Chute Mark II, ya bilge rat, t' first model rocket.

Construction:
T' parts include:

• 3" PML phenolic airframe
• Custom turned hardwood nose
• 1/8" basswood fins glassed with Aerosleeve fiberglass sleeve
• 1/4" ply centerin' rings
• 38mm PML phenolic motor tube
• ACME conformal 1/4" launch lugs
• 8 feet o' 5/16" tubular nylon shock cord
• Slimline 38mm retainer with 29mm adapter

After doin' t' 2x mid-power upscale o' t' Rock-A-Chute t' go with me Semroc clone o' t' Mark II, I set out t' complete t' series with a high power version. Goin' by t' details provided by t' Semroc kit I designed this one around 3" phenolic tube from PML. Avast, me proud beauty! Well, blow me down! T' tube is a good choice, but me decision t' slot it myself by hand, matey, was not. Begad! Well, blow me down! I wore me hand out several times while cuttin' each o' t' slots with a hobby knife. Begad! I now buy me tubes pre-slotted.

T' design and build was straight forward for a simple 3FNC high power design. Blimey! T' fins are through t' wall t' t' motor tube and were glassed with 3" fiberglass sleeve from Aerosleeve. Begad! Blimey! This is a coarse weave and required a fair amount o' SuperFil t' fill in. Ahoy! Nay somethin' I'd recommend, shiver me timbers, but another point where I went after maximum hands on building.

T' shock cord was tied around t' motor tube and run betwixt t' body and edge o' t' forward centerin' rin' via a notch in t' ring. Begad! This was glued into t' aiframe and t' fins fitted and filleted one at a time. Ahoy! Aye aye! JB Weld was used on all parts that came in contact with t' motor tube so thar wouldn't be any heat problems. Avast! Avast, me proud beauty! All other epoxy was Devcon 2-ton. Blimey! After t' fins were set, me bucko, me hearties, t' aft centerin' rin' was glued in and t' Slimline put in place.

T' nose cone be custom turned out o' hardwood by Gordon "Sandman" Angello o' Roachwerks. Ya scallywag! Blimey! Aye aye! Blimey! It is a work o' art. Ahoy! Blimey! Blimey! Blimey! It was a shame t' cover that nice wood finish with crass red gloss paint, but this was after all a reproduction. Blimey! Blimey! Avast, me proud beauty! Blimey! T' heavy screw eye in t' nose was reinforced by paintin' epoxy around and through t' eye t' prevent it from unscrewin' or pullin' out. Rather than goin' with a scale launch lug (it would have been roughly BT55 sized), ya bilge rat, I went with ACME conformal launch lugs. These and t' Slimline motor retainer are t' only outward violations o' t' strict upscale.

Finishing:
T' spirals in t' airframe were filled by coverin' t' entire tube with spackle. Aye aye! Spackle was also painted on t' fins t' fill any small bits nay quite filled by t' SuperFil. Begad! Arrr! This was then sanded down and primed. T' paint job be predetermined by t' upscalin' with t' body and fins all fluorescent orange and t' nose cherry red. After paintin' and dryin' it be all coated several times with Minwax Polycrylic. Begad! This turned out t' be a "gotcha" as t' Polycrylic made t' fluorescent paint mottled, so that it appears thar are different shades o' orange. Avast, me proud beauty! Nay a real bad lookin' effect, me hearties, ya bilge rat, but certainly nay perfect.

Flight:
I put in a Nomex ejection protector from Giant Leap, so no waddin' was required. I used a Covert Recovery CR-4 17" parabolic chute for recovery attached with dual quick-links.

Simulation o' 50 ounces with a G64 for t' rocket plus 29mm adapter and RMS motor gave an altitude o' 760' with apogee at 6.5 seconds. Ahoy! I went with a G64-7 for t' test flight.

T' flight went as expected, but t' ejection was delayed and deployment was 2 seconds late with 3 pounds o' rocket whistlin' downward.

Recovery:
When t' ejection did go off, shiver me timbers, t' chute deployed very hard, me bucko, but t' rocket stopped dead in t' air then came down normally. T' dual quick-links (1/8", rated at 220 lbs each) be probably a good idea. Ya scallywag! Ahoy! I haven't seen them fail before, arrr, ya bilge rat, but I suspect it might have if I'd only used one.

After recovery, it turned out thar were two small zippers, me bucko, 180 degrees apart. Aye aye! Ahoy! These were easily repaired.

Summary:
Although a "primitive" design, me bucko, t' Rock-A-Chute profile is a good one and consistently flies well. Arrr! Well, me hearties, blow me down! This version proves it scales up successfully. Begad! It is by no means a high performance design, matey, but it's still a crowd pleaser. Begad! A CON was a choice o' mine, me hearties, shiver me timbers, nay a function o' t' design which was choosin' t' slot t' phenolic airframe tube by hand with a knife. Begad! Well, me bucko, blow me down! Bad idea.