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

Brief:
3x upscale o' Rock-A-Chute Mark II, 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. Begad! Goin' by t' details provided by t' Semroc kit I designed this one around 3" phenolic tube from PML. T' tube is a good choice, ya bilge rat, but me decision t' slot it myself by hand, was not. Aye aye! I wore me hand out several times while cuttin' each o' t' slots with a hobby knife. Arrr! Aye aye! I now buy me tubes pre-slotted.

T' design and build was straight forward for a simple 3FNC high power design. Arrr! T' fins are through t' wall t' t' motor tube and were glassed with 3" fiberglass sleeve from Aerosleeve. Blimey! This is a coarse weave and required a fair amount o' SuperFil t' fill in. Arrr! Begad! Nay somethin' I'd recommend, 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. Ahoy! Begad! This was glued into t' aiframe and t' fins fitted and filleted one at a time. Ya scallywag! JB Weld was used on all parts that came in contact with t' motor tube so thar wouldn't be any heat problems. All other epoxy was Devcon 2-ton. After t' fins were set, 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. Begad! Avast, matey, me proud beauty! It is a work o' art. Arrr! Begad! It was a shame t' cover that nice wood finish with crass red gloss paint, me bucko, but this was after all a reproduction. Ya scallywag! 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. Arrr! Well, blow me down! 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. Blimey! 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. Begad! Spackle was also painted on t' fins t' fill any small bits nay quite filled by t' SuperFil. Begad! This be then sanded down and primed. Ahoy! T' paint job be predetermined by t' upscalin' with t' body and fins all fluorescent orange and t' nose cherry red. Arrr! Begad! After paintin' and dryin' it was all coated several times with Minwax Polycrylic. Avast! This turned out t' be a "gotcha" as t' Polycrylic made t' fluorescent paint mottled, ya bilge rat, so that it appears thar are different shades o' orange. Well, blow me down! Nay a real bad lookin' effect, me hearties, but certainly nay perfect.

Flight:
I put in a Nomex ejection protector from Giant Leap, arrr, so no waddin' be 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! Aye aye! Blimey! I went with a G64-7 for t' test flight.

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

Recovery:
When t' ejection did go off, t' chute deployed very hard, but t' rocket stopped dead in t' air then came down normally. Arrr! Blimey! T' dual quick-links (1/8", matey, rated at 220 lbs each) was probably a good idea. I haven't seen them fail before, 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. Avast, me proud beauty! These were easily repaired.

Summary:
Although a "primitive" design, t' Rock-A-Chute profile is a good one and consistently flies well. Ya scallywag! Blimey! Blimey! Blimey! This version proves it scales up successfully. It is by no means a high performance design, but it's still a crowd pleaser. Aye aye! Blimey! Blimey! Blimey! A CON was a choice o' mine, nay a function o' t' design which was choosin' t' slot t' phenolic airframe tube by hand with a knife. Ahoy! Blimey! Ahoy! Blimey! Blimey! Blimey! Bad idea.