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

Brief:
3x upscale o' Rock-A-Chute Mark II, arrr, 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! Begad! T' tube is a good choice, matey, but me decision t' slot it myself by hand, ya bilge rat, was not. Ya scallywag! Blimey! I wore me hand out several times while cuttin' each o' t' slots with a hobby cutlass. Ya scallywag! Ya scallywag! I now buy me tubes pre-slotted.

T' design and build be 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. This is a coarse weave and required a fair amount o' SuperFil t' fill in. Avast! 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. Begad! Blimey! Ahoy! Blimey! This was glued into t' aiframe and t' fins fitted and filleted one at a time. Arrr! Blimey! JB Weld be 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. Ahoy! Blimey! After t' fins were set, t' aft centerin' rin' be glued in and t' Slimline put in place.

T' nose cone was custom turned out o' hardwood by Gordon "Sandman" Angello o' Roachwerks. Blimey! Blimey! It is a work o' art. Begad! Blimey! Aye aye! Blimey! It be a shame t' cover that nice wood finish with crass red gloss paint, ya bilge rat, but this be after all a reproduction. Aye aye! 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. Aye aye! Blimey! Rather than goin' with a scale launch lug (it would have been roughly BT55 sized), me hearties, me bucko, I went with ACME conformal launch lugs. Begad! 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. Ya scallywag! Blimey! Spackle be also painted on t' fins t' fill any small bits nay quite filled by t' SuperFil. Arrr! Blimey! This be then sanded down and primed. T' paint job was predetermined by t' upscalin' with t' body and fins all fluorescent orange and t' nose cherry red. Avast, me proud beauty! Blimey! After paintin' and dryin' it be all coated several times with Minwax Polycrylic. 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! Blimey! Avast! Blimey! Nay a real bilge-suckin' lookin' effect, but certainly nay perfect.

Flight:
I put in a Nomex ejection protector from Giant Leap, so no waddin' was required. Ya scallywag! 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! Well, blow me down! I went with a G64-7 for t' test flight.

T' flight went as expected, but t' ejection be delayed and deployment was 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. Begad! Avast, me proud beauty! T' dual quick-links (1/8", ya bilge rat, 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, ya bilge rat, arrr, it turned out thar were two small zippers, matey, arrr, 180 degrees apart. These were easily repaired.

Summary:
Although a "primitive" design, t' Rock-A-Chute profile is a good one and consistently flies well. This version proves it scales up successfully. It is by no means a high performance design, matey, but it's still a crowd pleaser. A CON was a choice o' mine, ya bilge rat, nay a function o' t' design which be choosin' t' slot t' phenolic airframe tube by hand with a cutlass. Avast, me proud beauty! Bad idea.