Brief:
Cascade is a breakaway parallel-staged rocket standin' 33.75" tall, 2.6" diameter, and weighin' 17.5oz. Arrr! Aye aye! Two breakaway semi-cylindrical boosters are intended for 18mm B6-0 or C6-0 motors with a central 24mm motor in the main tube, shiver me timbers, originally intended for a E9-4. Blimey! If everythin' goes accordin' to plan, shiver me timbers, t' launch should feature 3-way cluster ignition with two boosters droppin' off t' main rocket smartly and returnin' by parachute while t' main rocket powers into t' stratosphere. Ya scallywag! With t' degree o' complexity and the overall weight o' t' build, shiver me timbers, ya bilge rat, matey, another very likely outcome is substantial re-kitting.

I never would have attempted this without t' EMRR 2006 Challenge pushing me. Design and construction were quite challenging. T' name "Cascade" stems from t' repeated elliptical motifs in all t' fins and noses, which evoke images o' waterfalls. Ya scallywag! Bein' somewhat o' a pessimist about this project, I think it may also end up referrin' t' t' volume of shredded parts cascadin' down all over t' launch vicinity. We'll see.

Construction:
T' boosters began as a single BT-70 tube section and NC70 nose cone. Ahoy! Aye aye! T' tube was halved lengthwise. Avast! T' nose cone was halved vertically. Avast! Avast! I have nay found a satisfactory way t' do this with me tools (no bandsaw) and I welcome suggestions. Ahoy! Avast! A kitchen knife worked better than me jigsaw.

Two CRs were halved and t' inner holes expanded and shifted t' accept BT-20 engine mounts. T' engine tubes were aligned t' be flush with t' flat edge o' t' half-tube. T' open sides o' t' half-tubes were closed with flat panels o' 1/16" balsa. Avast! Blimey! T' flat side o' t' nose was backed with a matchin' piece o' 1/4" balsa. Ya scallywag! Blimey! Note that this causes t' flat side o' t' booster t' have a ledge where the nose joins t' body. This is intentional t' aid mountin' on t' main rocket.

T' profile o' t' booster be traced onto a template, me bucko, me bucko, which be used to construct a flat mountin' panel which would be attached t' t' main rocket. Begad! Aye aye! The nose portion o' t' mountin' panel be 1/16" balsa and t' body portion was 1/4" balsa. Avast! Note that these thicknesses compensate for t' ledge on the booster.

Forward mountin' pins were constructed from paperclips. Avast! A trough was cut in t' booster nose cone with t' paper clips epoxied in. Aye aye! A square o' 1/16" balsa be cut to permit two inch-long lugs t' be glued in flush with one side and then this subassembly be glued into a trough cut in t' top o' t' 1/4" mounting panel portion. Begad! When t' booster nose blows, this will detach t' top o' the booster from t' main rocket.

T' bottoms o' t' boosters have small brackets which clip below t' body tube, me bucko, thus transferrin' t' upward thrust o' t' booster t' t' main body. These clips do nay secure t' boosters t' t' main rocket in any way, except they are slanted upwards and inwards t' prevent t' tails o' t' boosters from wobblin' durin' thrust. After t' booster nose detaches, this leaves t' rear of t' booster free t' simply fall away. Avast! Aye aye! [Note: none o' t' photos shows these clips, which were installed at t' end.]

This booster setup and attachment method was designed t' work separately for each booster. If a booster failed t' ignite, this design keeps it attached t' t' main rocket for t' entire flight.

T' center rocket be almost an afterthought. Ahoy! It has a 2.6 inch heavy duty BT-80 tube, me bucko, matey, elliptical nose cone, matey, me hearties, and a standard engine mount setup, me bucko, with Keelhaul®©™® tied t' t' top CR. It turned out t' be a major mistake t' use t' heavy duty BT-80 instead o' t' standard, because t' rocket turned out too heavy for its intended motor combination. Avast! T' next step was t' glue t' booster mounting panels t' t' main body.

Nearly 50 pieces of 3/32" basswood were used t' build t' fins. Blimey! Each fin was made from 2, 4, or 5 portions glued together t' ensure optimal grain orientation. Ahoy! Begad! T' small fins are centered on each booster. Ahoy! Arrr! T' long strakes attach 90 degrees around from these on t' main body centered betwixt booster mountin' panel edges. Begad! The main fins required more care. Arrr! These attach t' t' main body so that they are perpendicular t' t' main body tube and just touch t' booster mountin' panels at about a 45 degree angle. Aye aye! These fins are filleted t' t' body tube on the "outside" and t' top portion o' t' "inside", where the "inside" be t' fin side closest t' t' booster mount. This created a small cavity under t' mountin' panel and is enclosed by t' main fin with an open curvin' gap at t' top where t' booster nose curves away. Blimey! There is also a triangular gap at t' tail. Blimey! I scrapped plans t' fill these entrances t' the cavity due t' weight considerations.

Finishing:
After a depressin' amount o' fillin' and sanding, me bucko, it was time t' paint. Having rushed and screwed up me last paint job, I be determined t' take me time with this one, and t' results were excellent. Arrr! T' red and yellow are Rustoleum and the orange is Duplicolor Ceramic Engine Enamel. Ya scallywag! T' orange paint looks great, but it does require 1 week o' dryin' time. Light coats o' Krylon clear went over t' top.

Flight:
T' final rocket be pretty heavy with a lot o' tail weight. Well, blow me down! I figured I ought to give it a swin' test. Begad! T' results suggested that I really ought t' see my neurologist about dizzy spells, me hearties, but were inconclusive about t' rocket. Avast, ya bilge rat, me proud beauty! I couldn't bear t' add nose weight t' this beast, shiver me timbers, ya bilge rat, so I decided t' take my chances.

I opted t' use rail buttons so I could take full advantage o' a 6-foot rail for safety. Avast! I also pulled out me 36-inch competition mylar chute. Begad! This was overkill, but might give a softer landin' for those basswood fins if t' chute doesn't shred on ejection. Well, blow me down! I had some 14-inch chutes layin' around, me hearties, so I used these for t' booster pods without thinkin' about it too much.

A E9-4 has a burn time o' 2.8 seconds; t' B6-0 and C6-0 have burn times of 0.8 and 1.6 seconds, respectively. Avast, me proud beauty! Aye aye! T' spirit o' t' EMRR Challenge is t' have the boosters fall away quickly, ya bilge rat, so I opted for t' two B6-0s plus t' E9-4, savin' t' more powerful boosters for another day. Begad! I have no idea how high either motor combination would put t' rocket, me bucko, but I knew t' velocity at the end o' t' rail would be marginal at best.

First launch was at Mile High Mayhem. Ahoy! T' rocket struggled off t' rail with t' boosters poppin' off at t' neck-stretchin' altitude o' about 15 feet. They landed undamaged before t' chutes had time t' fully deploy. Blimey! T' good news was that t' B6-0 burn through did provide plenty o' forward pressure t' pop the pod noses, thus t' parallel stagin' worked about as well as one could hope.

T' main rocket clawed its way upward on an archin' trajectory, underpowered.

Recovery:
T' delay be too long for t' rocket's meager velocity, arrr, so t' ejection was considerably late. This caused t' chute t' shred on ejection, providing streamer recovery for t' 1 pound main rocket. Well, blow me down! Remarkably, only one fin broke on landing, and it was a clean break which can be easily repaired. Avast, me proud beauty! Avast! Blimey! T' chute shred also caused a near-zipper. Avast, me proud beauty! Avast! Blimey! I pushed t' tube back into shape.

Summary:
Since I built this for t' 2006 EMRR Challenge, matey, I'll repair and try launching again. Begad! Blimey! However, it is clear that I will need t' abandon t' idea o' a long burn-time differential betwixt t' pods and main rocket, me hearties, optin' instead for a main engine with greater initial thrust, shiver me timbers, shiver me timbers, like a E30 or F21.

Lookin' back on this project, a parallel-staged rocket with dropaway booster pods is a pretty ambitious project that I wouldn't recommend to beginners. Begad! Begad! It does open up a new corner o' t' hobby though for people looking for a serious challenge.