This be t' story o' two different rockets that are t' same. Begad! Avast, me proud beauty! 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. I had suggested after t' 2006 contest that more 1950’s "retro" style rockets might make a cool contest, so I be greatly pleased t' see that that was t' theme! I laid out me strategy for completin' me entry for the contest, matey, 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, ya bilge rat, nay necessarily t' one that was worth the most possible points!

My model o' CoolRockets.com’s Blast! was originally designed around Estes BT-80 tubing. Blimey! Ya scallywag! I intended t' use the nosecone recycled from a crashed Estes Fatboy. Aye aye! Arrr! For t' fins, I was thinkin' basswood more than balsa due t' t' extreme sweep. Begad! 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, matey, arrr, me bucko, so I knew that t' fin pattern would be fairly foreshortened and nay entirely accurate t' trace. Ya scallywag! After a bit o' scroungin' on CoolRockets.com, I found a picture o' t' Blast! in profile, shiver me timbers, matey, which I downloaded. Well, blow me down! Even though t' photo was very small and only web quality, me hearties, matey, matey, 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, matey, curved shape o' t' Blast! Blimey! for me EMRR Featured Tip (../../featured/tip_featured14.shtml)! This method be developed by Korey Kline and was 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. Begad! Blimey! I cut t' pie shapes out with scissors and an x-acto knife. Ahoy! Then I glued a section o' BT-60 tube into t' BT-80 with a centerin' ring. Begad! Blimey! T' BT-60 be goin' t' act as t' stuffer tube that me motor mount would slide into. 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. 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. Aye aye! Blimey! I cut out me paper patterns and spray glued them t' the basswood. Aye aye! Blimey! I used 1/8" for t' center and 1/16" for t' outer layers. Avast, me proud beauty! Blimey! I intended t' keep t' pattern on the wood t' eliminate t' need t' fill t' grain. Begad! Blimey! I found this technique worked fairly well. Begad! Blimey! After coatin' t' paper laminate with a thin layer o' superglue t' reduce t' "fuzzies" that are produced by sandin' paper, I was able t' achieve a nice finished, double thick fin, arrr, matey, me bucko, which I carefully adhered t' t' tail.

Another feature that I incorporated into me original design was an internal launch lug. I didn’t want a big, clunky lug marrin' t' look o' t' teardrop body. Blimey! Blimey! In assemblin' me motor mount, me hearties, I glue me lug t' t' motor tube and cut holes in t' centerin' rings thus allowin' t' launch rod t' pass through it. Arrr! 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. Blimey! Well, blow me down! Blimey! 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, ya bilge rat, t' rocket be essentially complete! T' shock cord and parachute were tied in and Blast! was ready t' fly. Rocksim said that t' design be unstable, but it doesn’t deal well with short stubby rockets. Aye aye! Avast! A quick swin' test confirmed Rocksim’s opinion… Nose weight would be needed. Ya scallywag! A couple o' fishing sinkers later, shiver me timbers, t' model be swingin' perfectly!

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

I was very excited t' make t' first flight o' me new creation. Begad! Aye aye! 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. After callin' a heads up, arrr, shiver me timbers, I hit t' launch button. Well, blow me down! T' rocket shot off t' pad quickly, but after t' initial thrust spike, arrr, thar be nay enough impulse t' maintain it’s trajectory. Well, blow me down! Blast! arched over sharply and cruise-missiled into t' sand behind the flight line without ejecting. Ya scallywag! As I be runnin' over t' retrieve it, shiver me timbers, t' ejection charge popped. Begad! T' motor mount must have become lodged from t' impact, as t' nosecone ejected and t' body tube ruptured and actually caught fire. Well, me bucko, blow me down! 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! Avast! Luckily, arrr, me hearties, arrr, t' tail cone and fins had survived the crash intact. Ya scallywag! Aye aye! 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. Aye aye! T' repair be nay pretty, arrr, me hearties, 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. Begad! Blimey! Oh, 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, ya bilge rat, I loaded up me trusty 18mm Aerotech case with a D13-4 reload. Again, a quick swin' test showed that t' model should be stable in flight. Arrr! Off t' t' pads once more. After a couple o' misfires (gotta love Copperheads), Blast! leapt off t' pad and wiggled it’s way into the sky. Ya scallywag! Ya scallywag! Maybe a little more nose weight t' straighten it out on t' next flight I thought. It arched over and was headed down, which be t' planned flight profile, ya bilge rat, matey, ya bilge rat, when t' ejection charged fired extremely energetically. Ahoy! T' shock cord snapped after bein' strained too far and t' parachute stripped. Begad! T' model again crashed into t' sand o' t' flying field, ya bilge rat, this time hard enough t' crush t' nose cone, matey, tear t' body tubin' and crunch one o' t' fins. 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…. Avast, me proud beauty! Or a lot! I was out o' Fatboy nosecones t' replace t' original one with, so just repairin' t' original again with an up scaled motor mount be nay goin' t' be possible. However, me bucko, arrr, me hearties, 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! be built essentially t' same as t' original, arrr, with a few improvements. 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 was runnin' out o' time t' make t' EMRR deadline! I decided t' forego the internal lug and use rail buttons. Ahoy! 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. Arrr! I used 3" LOC tubin' for the stuffer tube on t' upscale. Avast! Avast! For t' motor mount, ya bilge rat, I decided t' use 29mm. This should allow a high impulse G or H motor, which be me best guess at motor at t' start o' t' second design. I decided t' extend t' front o' t' motor tube through a double wall bulkhead just behind t' nosecone. Aye aye! 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, arrr, Big Blast! assembled very quickly. It came together from raw materials to completed construction over t' course o' a weekend. Avast, me proud beauty! Fillin' and finishin' would take place over t' next week, getting it up through primer.

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

T' early December DART launch was me final chance t' get a launch in on t' Big Blast. Well, blow me down! Well, arrr, blow me down! T' rocket fully completed came in at a dry weight o' just under four pounds. Well, blow me down! 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. Blimey! Probably either a H165 Redline or a H238 Blue Thunder. Arrr! Blimey! 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. Blimey! With t' 10 ounces o' nose weight I had added, it swung perfectly.

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

Big Blast! Blimey! 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. For a rocket with low multipliers for difficulty for t' contest, me hearties, I still found ways t' make t' builds challenging. Aye aye! Rear ejection, matey, tapered tubing, shiver me timbers, me bucko, finishin' well beyond me normal levels, up scaled design. Blimey! Begad! 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