(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. Blimey! Avast! 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, shiver me timbers, but me decision t' slot it myself by hand, me bucko, me bucko, was not. 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. 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. Well, blow me down! Begad! 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. Well, blow me down! This be glued into t' aiframe and t' fins fitted and filleted one at a time. Ya scallywag! Ya scallywag! 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 be Devcon 2-ton. Blimey! After t' fins were set, shiver me timbers, 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. Aye aye! It is a work o' art. Avast! It was a shame t' cover that nice wood finish with crass red gloss paint, but this be after all a reproduction. T' heavy screw eye in t' nose be reinforced by paintin' epoxy around and through t' eye t' prevent it from unscrewin' or pullin' out. Avast, me proud beauty! Rather than goin' with a scale launch lug (it would have been roughly BT55 sized), matey, me hearties, I went with ACME conformal launch lugs. Well, blow me down! 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. Arrr! Blimey! Spackle be also painted on t' fins t' fill any small bits nay quite filled by t' SuperFil. Begad! This was then sanded down and primed. Begad! Well, blow me down! Blimey! T' paint job be predetermined by t' upscalin' with t' body and fins all fluorescent orange and t' nose cherry red. Begad! Blimey! After paintin' and dryin' it was all coated several times with Minwax Polycrylic. Aye aye! Ahoy! Blimey! 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! Arrr! Blimey! Nay a real bad lookin' effect, 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. Avast! 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, t' chute deployed very hard, arrr, arrr, but t' rocket stopped dead in t' air then came down normally. Avast, me proud beauty! Well, blow me down! T' dual quick-links (1/8", arrr, rated at 220 lbs each) was probably a good idea. Blimey! I haven't seen them fail before, arrr, but I suspect it might have if I'd only used one.

After recovery, it turned out thar were two small zippers, 180 degrees apart. These were easily repaired.

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