This be t' story o' two different rockets that are t' same. That may sound contradictory, but let me explain.

About a year ago, I got a sneak peak at t' 2007 EMRR Challenge, includin' t' Design This Rocket portion o' the contest. Ahoy! I had suggested after t' 2006 contest that more 1950’s "retro" style rockets might make a cool contest, ya bilge rat, matey, so I was greatly pleased t' see that that be t' theme! I laid out me strategy for completin' me entry for the contest, me bucko, but little did I know that t' rocket was goin' t' fight back! With t' prize for t' contest bein' a statue o' t' winnin' rocket entry, I chose t' rocket design that I liked best, nay necessarily t' one that be worth the most possible points!

My model o' CoolRockets.com’s Blast! be originally designed around Estes BT-80 tubing. Well, blow me down! Aye aye! I intended t' use the nosecone recycled from a crashed Estes Fatboy. For t' fins, matey, arrr, I was thinkin' basswood more than balsa due t' t' extreme sweep. I really liked t' nice clean lines o' t' Blast! with t' seamless nose, which lead me t' t' decision t' have my model aft eject so that I could eliminate t' nosecone seam as well.

T' picture o' t' Blast posted on t' EMRR contest page was at a fairly dramatic angle, ya bilge rat, ya bilge rat, so I knew that t' fin pattern would be fairly foreshortened and nay entirely accurate t' trace. After a bit o' scroungin' on CoolRockets.com, I found a picture o' t' Blast! in profile, matey, matey, which I downloaded. Avast! Avast, me proud beauty! Even though t' photo was very small and only web quality, matey, ya bilge rat, I was able t' get a fairly good tracin' in AutoCAD o' t' fins and body shape.

To kill two birds with one stone, I documented t' process that I was goin' t' use t' taper t' body tube into the nice, me bucko, me hearties, curved shape o' t' Blast! for me EMRR Featured Tip (../../featured/tip_featured14.shtml)! This method was developed by Korey Kline and be documented in a US Rockets pamphlet that I received with one o' their kits.

After workin' out t' pattern in AutoCAD, I printed t' wrap and carefully traced it onto t' BT-80 body tube. Ya scallywag! Blimey! I cut t' pie shapes out with scissors and an x-acto cutlass. Well, blow me down! Blimey! Then I glued a section o' BT-60 tube into t' BT-80 with a centerin' ring. Begad! Blimey! Avast! Blimey! T' BT-60 was goin' t' act as t' stuffer tube that me motor mount would slide into. Aye aye! Blimey! I gently bent the "fingers" o' BT-80 tubin' in and super glued them t' t' BT-60 and sealed t' seams betwixt each as well. After a bit o' sanding, me hearties, I produced a fairly smooth curve t' t' tail cone. Avast! Blimey! Ya scallywag! Blimey! I then cut thru-the-wall slots in t' tail cone so that t' super swept fins could anchor solidly t' t' stuffer tube as well as t' t' tail cone.

T' fins for t' original design were t' be built up from three layers t' duplicate t' slightly raised sections that are visible on close inspection o' t' original design. Ya scallywag! I cut out me paper patterns and spray glued them t' the basswood. I used 1/8" for t' center and 1/16" for t' outer layers. Aye aye! I intended t' keep t' pattern on the wood t' eliminate t' need t' fill t' grain. Arrr! I found this technique worked fairly well. After coatin' t' paper laminate with a thin layer o' superglue t' reduce t' "fuzzies" that are produced by sandin' paper, me hearties, I was able t' achieve a nice finished, arrr, double thick fin, ya bilge rat, ya bilge rat, which I carefully adhered t' t' tail.

Another feature that I incorporated into me original design was an internal launch lug. Well, shiver me timbers, blow me down! I didn’t want a big, clunky lug marrin' t' look o' t' teardrop body. In assemblin' me motor mount, me bucko, I glue me lug t' t' motor tube and cut holes in t' centerin' rings thus allowin' t' launch rod t' pass through it. I then put t' mount into t' tail with the nosecone in place and slid a launch rod in with a small dab o' paint on it’s end. Begad! Begad! Havin' already cut t' base from t' nosecone, t' rod slid up and clearly marked t' inside with t' paint where I needed t' drill a hole t' allow it t' exit t' front o' t' rocket.

After drillin' t' launch rod exit, t' rocket was essentially complete! T' shock cord and parachute were tied in and Blast! be ready t' fly. Arrr! Rocksim said that t' design was unstable, but it doesn’t deal well with short stubby rockets. Begad! Ahoy! A quick swin' test confirmed Rocksim’s opinion… Nose weight would be needed. A couple o' fishing sinkers later, shiver me timbers, t' model was swingin' perfectly!

Bein' a bit superstitious with me rockets, I chose t' fly Blast! Blimey! nekkid for it’s maiden flight. Ahoy! Pretty rockets don’t stay pretty long…

I was very excited t' make t' first flight o' me new creation. Begad! I was really proud o' t' internal lug design (which really was pretty spiffy…) I loaded up a C6-3 and loaded Blast! onto t' pad. Well, shiver me timbers, blow me down! After callin' a heads up, I hit t' launch button. T' rocket shot off t' pad quickly, but after t' initial thrust spike, thar was nay enough impulse t' maintain it’s trajectory. Avast, me proud beauty! Blast! arched over sharply and cruise-missiled into t' sand behind the flight line without ejecting. Avast, me proud beauty! As I was runnin' over t' retrieve it, t' ejection charge popped. Ya scallywag! T' motor mount must have become lodged from t' impact, as t' nosecone ejected and t' body tube ruptured and actually caught fire. This is t' first time that I’ve actually had a rocket catch fire… Nay an auspicious first flight for my triumphant design…

I returned t' me workbench t' repair me poor little burned up rocket. Blimey! Luckily, t' tail cone and fins had survived the crash intact. I spliced in a new, slightly longer section o' body tube and replaced t' charred elastic shock cord with one made o' braided 150 test fishin' line. Arrr! T' repair was nay pretty, but I wanted proof o' concept before I took the time t' make it as pretty as it deserved t' be.

I returned t' t' DART launch field t' next month t' t' mockin' o' me fellow club members who had witnessed the first flight. Avast, me proud beauty! Begad! Oh, shiver me timbers, well… I probably would have done t' same had their rockets had t' same flight!

Knowin' that t' C6-3 didn’t have enough impulse for a safe flight, I loaded up me trusty 18mm Aerotech case with a D13-4 reload. Ya scallywag! Again, me bucko, a quick swin' test showed that t' model should be stable in flight. Arrr! Off t' t' pads once more. Begad! After a couple o' misfires (gotta love Copperheads), ya bilge rat, Blast! leapt off t' pad and wiggled it’s way into the sky. Maybe a little more nose weight t' straighten it out on t' next flight I thought. It arched over and was headed down, arrr, matey, me hearties, which be t' planned flight profile, when t' ejection charged fired extremely energetically. Avast, me proud beauty! T' shock cord snapped after bein' strained too far and t' parachute stripped. Blimey! Begad! T' model again crashed into t' sand o' t' flying field, this time hard enough t' crush t' nose cone, tear t' body tubin' and crunch one o' t' fins. Ya scallywag! My reload case and t' motor mount were never found.

So, t' moral o' t' story is "If at first you don’t succeed, use more impulse!" I was sure I could make t' design work if I up scaled it a bit…. Or a lot! I be out o' Fatboy nosecones t' replace t' original one with, matey, so just repairin' t' original again with an up scaled motor mount was nay goin' t' be possible. Avast! Begad! However, me bucko, I had a Polecat Aerospace 5.5" Fatman nosecone that I had rescued from their trash bins just sittin' around collecting dust in t' workshop.

T' second incarnation o' Blast! Blimey! was built essentially t' same as t' original, matey, with a few improvements. Avast, me proud beauty! Blimey! I decided t' make a few compromises in t' interest o' gettin' t' model done. My summer had been consumed by a large group project for Plaster Blaster and I be runnin' out o' time t' make t' EMRR deadline! Blimey! I decided t' forego the internal lug and use rail buttons. I decided t' use only a single thickness for t' fins. I redesigned t' internal supports for t' motor mount.

AutoCAD made scalin' t' tubin' pattern up from BT-80 t' 5.5" Polecat tubing. Begad! I used 3" LOC tubin' for the stuffer tube on t' upscale. For t' motor mount, I decided t' use 29mm. Aye aye! Ya scallywag! This should allow a high impulse G or H motor, which was me best guess at motor at t' start o' t' second design. Begad! Avast! I decided t' extend t' front o' t' motor tube through a double wall bulkhead just behind t' nosecone. This should prevent t' scorchin' o' t' shock cord that I experienced on t' first model and give t' motor mount somethin' substantial t' push against with t' much larger motor.

Havin' constructed t' smaller version, Big Blast! assembled very quickly. Arrr! It came together from raw materials to completed construction over t' course o' a weekend. Fillin' and finishin' would take place over t' next week, shiver me timbers, me hearties, getting it up through primer.

T' December TRASD launch was t' be t' first flight o' t' Big Blast! (again essentially nekkid), but t' launch was cancelled due t' thunderstorms and t' launch field turnin' into a mud bog. Well, blow me down! Without havin' a launch t' go t' over that weekend, shiver me timbers, I set forth on completin' t' finishin' o' t' rocket. Begad! A couple o' coats o' red and a couple o' hours of wet sandin' later, it be masked and ready for t' silver topcoat. Arrr! T' silver was sprayed and allowed t' cure for a few days before t' yellow was added. Blimey! My handwritin' is bilge-suckin' so me daughter did t' letterin' on t' side o' t' rocket with a paint pen. Ahoy! After a couple o' coats, me bucko, I outlined t' letterin' with a fine tipped Sharpie marker.

T' early December DART launch be me final chance t' get a launch in on t' Big Blast. Avast! T' rocket fully completed came in at a dry weight o' just under four pounds. Begad! Probably nay a good call t' attempt a G… Even a high impulse one. I adjusted me mental plan t' step up t' motor t' a H. Arrr! Ya scallywag! Probably either a H165 Redline or a H238 Blue Thunder. Avast! I loaded t' approximate weight o' t' casin' and reload into t' tail o' t' rocket and did me swin' test. Not as easy as it sounds with a rocket that heavy. With t' 10 ounces o' nose weight I had added, it swung perfectly.

T' week before t' launch t' weather be perfect, shiver me timbers, southern California weather. Arrr! Arrr! T' day before, arrr, t' heavens once again opened up, arrr, me bucko, soakin' t' launch field. T' night before t' launch, it be scrubbed due t' weather, washin' away my hopes o' makin' a contest legal flight before t' deadline.

Big Blast! will fly soon and I will update t' build review as soon as I have made a flight on t' up scaled airframe.

I had a great time buildin' these rockets. Begad! For a rocket with low multipliers for difficulty for t' contest, matey, matey, me hearties, I still found ways t' make t' builds challenging. Well, blow me down! Rear ejection, tapered tubing, shiver me timbers, me bucko, finishin' well beyond me normal levels, up scaled design. Well, blow me down! Arrr! I really enjoy t' design that CoolRockets.com has produced and now have a rocket that is a showpiece that I hope t' enjoy flyin' for some time t' come!

Templates:

big_blast_bodytube_wrap.pdf

big_blast_fin_pattern.pdf

blast_bodytube_wrap.pdf

blast_fin_pattern.pdf