Brief:
In me early days o' me rocketry odyssey, shiver me timbers, clusterin' was nay a technique t' which I gave much thought. Blimey! Begad! This be largely due t' t' fact that, ya bilge rat, me hearties, shiver me timbers, in 1977, t' only commercially available Estes kits that featured clustered engines were t' wildly expensive (to a kid who caddied for rocket money) Saturn V and Saturn 1B, or t' Scrambler, (eggs were for schoolbuses, ya bilge rat, shiver me timbers, nay rockets.) Until 2001, me hearties, matey, arrr, I had never even heard o' t' Astron Cobra or Astron Ranger, two poor man's cluster kits from t' early days o' Estes Industries (when clusterin' was t' closest thin' t' high power.) T' Cobra became me first choice for a clustered classic, mostly because o' t' Ranger's close resemblance t' t' Big Bertha. (I have t' BMS cone for a Ranger project. Aye aye! Avast, shiver me timbers, me proud beauty! I just wanted t' start with somethin' a little different.)

Construction:
Parts Needed:

• BT-60D main body tube 11"
• BT-50S payload tube 4"
• 3 BT-20J engine tubes 2.75"
• BNC-50K nose cone (BMS)
• TA-5060 transition section (BMS)
• 3 EB-20A thrust rings
• 3 engine hooks (optional)
• 10" Keelhaul®©™ thread
• 24" sewin' elastic 1/4" width
• 3/32" basswood fin stock
• Estes Recovery Wadding
• white glue
• wood glue
• decals
• launch lug
• 18" parachute
• screw eye

T' nice thin' about clonin' t' Astron Cobra is that aside from t' clustered engine mount, t' rocket is an extremely straightforward 4fnc project. Blimey! Ya scallywag! This allows even t' relative novice t' produce a great lookin' clone. Begad! If you can cut balsa, glue fins on straight and have rudimentary finishin' skills, matey, shiver me timbers, t' Cobra stands a good chance o' bein' a rocket that you'll be proud t' both fly and display. Constructin' t' engine mount be t' only part o' t' project that can be slightly tricky (emphasis on slightly.)

T' cluster mount is constructed by gluin' three equal lengths o' BT-20 in a triangular shape. Ahoy! In this configuration they are a perfect fit inside a standard diameter BT-60 body tube. Ahoy! Avast! When t' completed mount is installed in t' rocket, shiver me timbers, me bucko, thar will be four spots which have t' be sealed t' guard against ejection gases escapin' (and causin' a cluster.......failure.) T' first and easiest t' deal with be t' space that runs down t' middle betwixt t' three tubes. Begad! I took care o' this space by first gluin' two o' t' tubes together, side by side. Blimey! Well, blow me down! When these two were dry, arrr, matey, I ran a heavy bead o' glue down t' middle o' t' two tubes, and before placin' t' third tube into place, I put a ten inch piece o' Keelhaul®©™ into t' glue. This accomplishes two things. Arrr! It effectively seals off this potential exhaust gas escape path, and t' Keelhaul®©™ helps t' both strengthen and fireproof t' recovery system. Ahoy! Works great, shiver me timbers, and best o' all you don't have t' worry about t' old Estes tri-fold paper shock cord mount bein' blown out by t' force o' t' triple ejection charge.

T' three remainin' potential gas escape spots occur at t' spots where t' outside o' t' engine tubes come into contact with t' inside o' t' body tube wall. Begad! Aye aye! These can be taken care o' in one o' two ways, me bucko, or both if you want an added measure o' insurance. Blimey! Ahoy! T' first method involves placin' a 2060 engine mount (like t' one that comes in a stock Big Bertha kit) on top o' t' three engine tubes and gluin' it securely in place. Aye aye! Once t' glue dries, t' portion o' t' mount that covers t' tops o' t' engine tubes can be cut or filed away t' keep t' ejection passages cleared. Arrr! (I didn't find out about this method until too late. Needless t' say, this should be done before t' structure is mounted in t' engine tube.) T' second method involves takin' glue soaked wads o' Estes recovery waddin' and fillin' t' spaces until a leak-free seal is achieved. Well, blow me down! This method also has t' added advantage o' strengthenin' t' whole engine mount area. Arrr! T' disadvantage o' this method be t' mess involved. Blimey! Glue soaked recovery waddin' is best handled in small clumps as it tends t' shred when wet and it gets all over EVERYTHING! While both o' these methods done correctly will provide you with a leak proof seal, usin' both o' them together almost guarantees that t' ejection charges go upward as intended without potentially disastrous leaks. Begad! I used an earlier version o' t' Cobra plans for t' build, matey, but a later plan includes instructions on usin' engine hooks. It's a relatively simple modification, but I've had no problems with friction fittin' early clones, arrr, and I prefer t' keep them as close t' t' original on t' outside as possible.

Finishing:
T' Astron Cobra was produced from 1963 t' 1973, and as an early Estes kit it did nay have a strongly defined paint and decal scheme over it's lifetime. Blimey! Early catalogs showed it brightly painted in a hot pink/white/black scheme with somewhat generic military markings, while t' 1971-73 catalogs showed it as a mostly white rocket with blue fins and nose cone. This version was also given a minimal decal treatment with only a red, vertical UNITED STATES and a small black roll pattern decal t' distinguish it. Well, blow me down! I went with t' later version, usin' t' SPEV decal scan on JimZ's page for t' UNITED STATES and t' old Astron Sprint scan for t' black roll decal. Begad! I printed these out o' Bel Decal paper and they came out lookin' great.

Construction Rating: 5 out o' 5

Flight:
T' Cobra has only flown once t' date, at a club launch last summer before me personal rocketry drought began. Avast, me proud beauty! It was an impressive flight, as clusters generally are, me bucko, with plenty o' smoke and noise from t' trio o' C6-5's. Avast! With it's oversized fins t' Cobra arced into t' breeze somewhat, me bucko, but these fins were also undoubtedly responsible for t' unwaverin' stability o' t' flight.

Recovery:
Recovery took place several hundred feet downrange with no flight damage, but plenty o' scorchin' around t' engine mounts. Begad! (This looks cool though.) T' parachute also got slightly toasted, arrr, due t' t' undoubtedly hefty ejection charge o' t' C6-5's. Blimey! Next time I'll go a bit heavier on t' dog barf wadding, ya bilge rat, and if I build another it will probably be equipped with one o' t' available pieces o' perma wadding.

Flight Rating: 5 out o' 5

Summary:
PRO'S:

1. Any time you can fly somethin' that can legitimately fly t' Astron name, that's a plus.
2. Clusters are cool.

CON'S:

1. Did I mention that sealin' t' exhaust holes with glue and waddin' is messy? I had it all over everything. Begad! Ahoy! (I'd almost rather be super glued t' t' cat.)

Overall Rating: 5 out o' 5