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

T' rocket can recover perfectly usin' long motor delays or with an altimeter in t' payload bay. Ahoy! Dual deployment is also possible. Avast, me proud beauty! Well, blow me down!

This rocket is inspired by the Quadra G, 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. Blimey! 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. Ya scallywag! Aye aye!

T' body tubes are 2 48 inch lengths o' Maximum Thrust Rocketry 4 inch motor tubes. Avast, me proud beauty! Avast, me proud beauty! They are paper and ultra thick and strong. Ahoy! 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. Aye aye! 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. Avast! Ahoy! These couplers are affixed in place by generous amounts o' West Systems slow epoxy.

There are 4 fins, matey, matey, fashioned from 2 pieces o' .125 inch thick G10 from Scott Eakins in t' ROL auctions. 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. Arrr! Blimey! T' trailing edges will be 12 inches each once t' two pieces are slotted down t' middle and interlocked together at right angles. Well, blow me down! T' assembly gets a thorough epoxy fillet in t' middle. Aye aye! Glass it with a strip o' 4 oz weight glass cloth if you plan t' use really hot motors with high average thrust. Arrr!

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, ya bilge rat, me bucko, shiver me timbers, 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. Avast, me proud beauty! t' remainin' length o' 18 t' 24 inches extends outward from the main body. Well, blow me down! Be sure that t' tubes are flush at t' ends, that is, 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. Begad! Avast, me proud beauty! weight fiberglass cloth. Ahoy! Aye aye! I also glassed t' launch lugs onto t' airframe. Well, blow me down! the airframe can be glassed as well, but I only did t' tops o' both and t' bottom where t' motor tubes start, for stress reinforcement and zipper prevention. Well, blow me down! Begad! I also glassed t' fins t' t' motor tubes. Aye aye! Well, arrr, blow me down! I did this with strips o' glass cloth. t' entire fin face can be glassed, me bucko, but I did nay choose t' do so. You might if you really push this rocket with mighty motors. Begad!

1/4 inch birch centerin' rings provide more internal support and are between the first 2 6 inch lengths o' phenolic internal couplers. 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. Arrr! Blimey! 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. I used square knots, nay granny knots. Ya scallywag! Blimey! T' Keelhaul®©™® came from Rocket Silo and t' bungee came from American Science and Surplus. Begad!

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. This assemble is screwed into place with 6 wood screws, me bucko, nay epoxy, ya bilge rat, because this allows removal and replacement o' electronics and bays from a point in the rocket nay too high t' arm on t' pad. Avast, me proud beauty! 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. Begad!

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, a ROL online auction vendor. Well, blow me down! Ahoy! T' shock cord attached aftward at a 1/4 inch birch centerin' rin' halfway down t' payload tube. I'd attach it lower, but I need space for t' protective bay needed for t' altimeters below. Blimey!

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

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

I decorated it in purple and orange, me hearties, with metallic accents from self adhesive mylar from local hobby shops. This also coordinated with t' two chutes, ya bilge rat, shiver me timbers, 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. I used 4 J350's. Ya scallywag! Blimey! One o' them was prepped with a long delay and the other 3 were nay given charges, me bucko, just t' trackin' delay grains, shiver me timbers, and their delay wells were plugged with grease and sealed with duct tape. Aye aye! Blimey! There were aft loops of piano wire embedded in t' fillets used t' affix t' fins, matey, 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 be attached. Begad! Well, blow me down! I didn't want any of t' motors t' be ejected. Ahoy! I anticipated a fast and high flight. Aye aye! Ya scallywag!

Nomex®/Keelhaul®©™® chute protectors were employed with redundant worm bed wadding in t' prep. Arrr! 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, ya bilge rat, so I screwed on t' nose and sealed the payload bay and flew t' bird with t' motor ejection. Ahoy! Blimey! I really had wanted to stress test t' altimeter for me upcomin' level 3 flight, matey, but that was nay to be. 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. I used 4 low current large tungsten bridge igniters from Fire in t' Hole, ya bilge rat, arrr, and a large marine 12 volt deep cycle battery. Begad! T' launch rod is a lightnin' rod 3/4 inch thick by 7 feet long.

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

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

Summary:
If thar's any CON, shiver me timbers, ya bilge rat, clusters do cost more t' fly. But thar's nothin' like the roar you get from multiple motors. Begad! Begad! I be high on t' adrenaline for weeks. 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, ya bilge rat, or get professionally made ones from Fire in t' Hole. Ahoy! That will ensure that all t' motors light.