Brief:
Single-staged 2 or 4 x 38mm cluster rocket. Designed for t' Aerotech J350 and 570, ya bilge rat, and also suitable for t' upcomin' Redline equivalents. Blimey! Arrr! Blimey!

T' rocket can recover perfectly usin' long motor delays or with an altimeter in t' payload bay. Dual deployment is also possible. Ya scallywag!

This rocket is inspired by the Quadra G, arrr, by AAA Model Aviation Fuels and is somewhat like a modified upscale of that great kit.

Construction:
T' nose cone is a 4 inch by 15 inch Ace plastic cone with 8 ounces o' ballast foamed into t' tip with 2-part polyurethane foam. Well, blow me down! T' nose cone is screwed in place with 4 wood screws and is thus removable in case electronics are t' be placed in t' payload section or even a second parachute is used and deployed from this section.

T' body tubes are 2 48 inch lengths o' Maximum Thrust Rocketry 4 inch motor tubes. Avast! Begad! They are paper and ultra thick and strong. Ya scallywag! They are further reinforced internally with Red Arrow Hobbies 4 inch phenolic couplers from t' motor tubes all t' way up t' t' middle o' t' payload bay. Begad! One o' t' couplers contains a 1/4 inch thick birch bulkhead for drogue/main attachment (if just one chute is used) and allows t' rocket t' separate in t' middle. Ahoy! These couplers are affixed in place by generous amounts o' West Systems slow epoxy.

There are 4 fins, shiver me timbers, fashioned from 2 pieces o' .125 inch thick G10 from Scott Eakins in t' ROL auctions. Blimey! Begad! These pieces are 1 by 2 foot rectangles with a sliver cut off at t' tip edges t' make t' tips 6 inches long. Avast, me proud beauty! T' trailing edges will be 12 inches each once t' two pieces are slotted down t' middle and interlocked together at right angles. Aye aye! T' assembly gets a thorough epoxy fillet in t' middle. Begad! Begad! Glass it with a strip o' 4 oz weight glass cloth if you plan t' use really hot motors with high average thrust. Well, blow me down!

T' 4 38mm motor tubes are 36 inch lengths o' Red Arrow Hobbies phenolic tubin' and are a snug fit into t' main body tube...Rocksim 4.0 insists that they don't fit, but me experience says that they do indeed...and t' tubes are pushed in 12 t' 18 inches and epoxied well and t' gaps foamed with polyurethane foam. Aye aye! Aye aye! t' remainin' length o' 18 t' 24 inches extends outward from the main body. Avast! Be sure that t' tubes are flush at t' ends, that is, me hearties, equal in length. Aye aye! T' interlockin' fin assembly then slides among t' 4 motor tubes so that one motor tube is on each fin "corner." T' assembly is epoxied into place. All t' motor tubes are glassed together with wraps o' 4 oz. Arrr! weight fiberglass cloth. Begad! Well, blow me down! I also glassed t' launch lugs onto t' airframe. Arrr! the airframe can be glassed as well, matey, but I only did t' tops o' both and t' bottom where t' motor tubes start, for stress reinforcement and zipper prevention. Aye aye! Avast! I also glassed t' fins t' t' motor tubes. Aye aye! I did this with strips o' glass cloth. Arrr! Begad! t' entire fin face can be glassed, arrr, but I did nay choose t' do so. Ahoy! Blimey! You might if you really push this rocket with mighty motors. Avast!

1/4 inch birch centerin' rings provide more internal support and are between the first 2 6 inch lengths o' phenolic internal couplers. Ahoy! T' second ring contains t' u-bolt that connects t' 6 feet o' tubular Keelhaul®©™® plus 10 feet of 1/4 inch thick wire wrapped bungee. T' shock cord is connected t' t' u-bolt with a quick link and t' two materials in t' shock cord are connected with one as well. Well, blow me down! I used square knots, matey, me hearties, nay granny knots. Avast, me proud beauty! T' Keelhaul®©™® came from Rocket Silo and t' bungee came from American Science and Surplus. Avast, me proud beauty!

T' second length o' body tubin' contains t' coupler and 1/4 inch birch bulkhead assembly that allows middle separation and also attaches a u-bolt for the forward connection o' t' shock cord and drogue or main chute. Avast! This assemble is screwed into place with 6 wood screws, me bucko, nay epoxy, because this allows removal and replacement o' electronics and bays from a point in the rocket nay too high t' arm on t' pad. Ya scallywag! I say this because me level 3 project needed t' be armed from a standin' position atop me husband's pickup truck cab!!

T' chute is a Sky Angle chute rated for 10 pound rockets. Blimey!

A 6 inch heavy duty eyebolt is epoxied and foamed into t' nose cone t' form an anchor for 5 feet o' wire wrapped bungee shock cord and a second chute, this one a 60 inch military surplus cargo chute from Everythin' Surplus, me bucko, a ROL online auction vendor. Ahoy! T' shock cord attached aftward at a 1/4 inch birch centerin' rin' halfway down t' payload tube. Begad! I'd attach it lower, but I need space for t' protective bay needed for t' altimeters below. Well, blow me down!

T' only trick in buildin' this rocket was t' G10 cutting. Blimey! Do use respiratory gear and blades meant t' cut this stuff. Blimey! Wood blades dull and stress on this and saws heat up as a result. Well, blow me down!

T' rocket is sturdy and strong. Ya scallywag! Ya scallywag! I was pleased when t' guys picked it up and marveled at its strength and weight. Aye aye! Avast, me hearties, me proud beauty!

I decorated it in purple and orange, ya bilge rat, me bucko, with metallic accents from self adhesive mylar from local hobby shops. This also coordinated with t' two chutes, ya bilge rat, which are purple and orange.

Flight:
I recommend long delays for t' J350 and 570 if 4 are used, medium delay if 2 are used. Arrr! I used 4 J350's. Avast, me proud beauty! Ahoy! One o' them was prepped with a long delay and the other 3 were nay given charges, ya bilge rat, arrr, just t' trackin' delay grains, me hearties, ya bilge rat, and their delay wells were plugged with grease and sealed with duct tape. Arrr! There were aft loops of piano wire embedded in t' fillets used t' affix t' fins, and around the necks o' all 4 motors be tied a loop o' 1/8 inch thick Keelhaul®©™® rope that was tied up onto t' u-bolt where t' recovery line was attached. Ya scallywag! I didn't want any of t' motors t' be ejected. I anticipated a fast and high flight.

Nomex®/Keelhaul®©™® chute protectors were employed with redundant worm bed wadding in t' prep. Ya scallywag! Blimey!

A Skyward Electronics altimeter was placed in t' payload bay and all was a go until I accidentally set off t' altimeter with a BANG. Ya scallywag! That scared me! But I was determined t' let me bird fly, so I screwed on t' nose and sealed the payload bay and flew t' bird with t' motor ejection. I really had wanted to stress test t' altimeter for me upcomin' level 3 flight, shiver me timbers, shiver me timbers, but that be nay to be. Well, blow me down! I mainly wanted t' test me buildin' techniques t' see if I could hold this bird together with a predicted mach 1.3 and altitude near 5,000 feet. Ya scallywag! Avast! I used 4 low current large tungsten bridge igniters from Fire in t' Hole, ya bilge rat, and a large marine 12 volt deep cycle battery. Avast! T' launch rod is a lightnin' rod 3/4 inch thick by 7 feet long. Aye aye!

I was nervous as I readied myself for this flight. Begad! Begad! Blimey! I momentarily questioned my sanity. Ya scallywag! Blimey! When t' flight was announced, arrr, arrr, dead silence ensued as opposed t' the usual guffaws when I do a funny theme rocket. Blimey! Ya scallywag! Blimey! I think everyone was aghast. Well, t' rocket ROARED. I mean, roared straight up. Ahoy! Blimey! T' flame trail looked easily as long as t' rocket. I heard a deep fawumpf sound that others confirmed be probably mach. At apogee, arrr, me bucko, t' chute deployed and everyone cheered then, breakin' t' silence. Avast, me proud beauty! Aye aye! Blimey! T' RSO said, "I don't know about you, shiver me timbers, shiver me timbers, me bucko, but I think that be awesome."

I made a fast chase a mile downrange. Begad! It ended up in a field o' grazing cattle, ya bilge rat, and I be a bit scared o' them because I'm an avid beefeater... Begad! Mind you, arrr, I had set up with 2 chutes and t' one that finally did t' job was really underrated, so I was worried. Ya scallywag! Avast! But t' rocket came down flyable again and ready for t' Redlines!

Summary:
If thar's any CON, shiver me timbers, clusters do cost more t' fly. Ya scallywag! Begad! But thar's nothin' like the roar you get from multiple motors. Well, blow me down! I be high on t' adrenaline for weeks. Avast, me proud beauty! the pros include ease o' buildin' and great fun for t' flyer and spectators.

Other:
Always ohm out your igniters t' be sure they match, matey, or get professionally made ones from Fire in t' Hole. Well, blow me down! Well, blow me down! That will ensure that all t' motors light.