Construction:
I didn't want t' go with a standard two-stage design, arrr, arrr, fins above fins. I decided on a rin' stabilized two stager.

T' initial pencil designs lead me t' a descendin' rin' profile. Begad! Avast, me hearties, me proud beauty! Three rings held in place by four small fins under each ring. Well, blow me down! T' model almost looks as if it were a three stager. T' highest painted band gives t' impression o' a smaller rin' and a fourth stage.

I went t' me scrap tubes and tried many until I found t' three sizes that would give t' visual o' "conical" descendin' rings.

T' model be built around a ST-10 airframe. Begad! T' booster is 3" long, t' sustainer body tube is 18".

T' rin' on t' booster is a 2-1/8" length o' BT-80. Aye aye! T' lowest rin' on t' sustainer is a 1-7/8" length o' BT-70. Begad! Ahoy! T' second higher sustainer rin' is 1-5/8" o' ST-16. Begad! Ya scallywag! And t' final (black painted) rin' is 1-3/8" wide.

T' fins were cut from 1/16" balsa and covered with 20lb copy paper. Arrr! Avast! I did this for two reasons. Ahoy! Ahoy! T' first is strength. Aye aye! Well, arrr, blow me down! Secondly, me bucko, me bucko, it would be impossible t' fill t' balsa after t' rings were glued in place.

T' balsa grain direction is opposite o' normal construction. T' grain follows t' trailin' edges o' all t' fins. T' trailin' edges are outside t' rings. I wanted t' give a little more protection for those exposed edges. Wrappin' paper over t' top o' t' rounded leadin' edge gave more than enough frontal rigidity. Aye aye! Ya scallywag! All fins were cut wide, shiver me timbers, which allowed me t' sand t' outside edges t' slip-fit t' rings in place.

I didn't glue t' rings in place until after spray paintin' t' main body and fins. Aye aye! I sprayed t' rings separately then glued them over t' fins. This gave me a no-mask paint job and clean color separations. Well, blow me down! T' only maskin' was t' paint t' wide black band on t' body tube.

On t' engine mounts, shiver me timbers, I followed t' old Centuri plans for their Arcon-Hi model. Avast! Blimey! Ya scallywag! Blimey! T' booster engine block is at t' aft o' t' booster. Ya scallywag! Blimey! T' sustainer block is normal, at t' top o' t' upper engine tube. T' only changes I made from t' Centuri plan be t' cut t' sustainer engine tube 1/8" shorter than t' original 3" length. Arrr! Blimey! Avast, me proud beauty! Blimey! This way t' engine would be extended 1/8" out t' back o' t' tubing. Aye aye! Blimey! T' engines are friction fit with maskin' tape. Ya scallywag! Blimey! Ya scallywag! Blimey! After a flight, arrr, I wanted a little bit o' t' casin' stickin' out t' remove it out with pliers.

Centuri style stagin' doesn't use clear tape t' hold t' engines together. Aye aye! Aye aye! Both stages are held together by two couplers. Ya scallywag! Simply friction fit t' engines in place then slide t' stages together.

[Click on t' followin' link t' download a PDF o' t' rocket.]

Flight:
T' first flight was on March 7 with a B6-0/A8-5 engine combination. T' first stage boost was good, ya bilge rat, but when t' sustainer ignited it be unstable. Recovery was safe. Blimey! Blimey! I added a hefty blob o' clay weight around t' large screw eye and nose cone base.

Later that day, matey, I tried again with t' same engines. Arrr! Blimey! This time it be stable and had a straight boost with good stagin' and recovery.

I thought it would be stable, ya bilge rat, but I hadn't used RockSim yet. Avast, me proud beauty! There was a large rin' area and plenty o' fins. Begad! Blimey! I thought t' body tube length would be adequate.

I went home and weighed t' clay. Well, blow me down! Blimey! I added t' equivalent weight in washers t' t' screw eye. Blimey! It required 0.4 oz (or five WW-7 washers from Semroc) o' nose weight t' be stable. Well, blow me down! Like every "different" design, sometimes extra nose weight is required.

T' third flight took place on May 2, 2009 at t' Orlando ROCK launch. I used B6-0/B6-6 engines. Avast! Avast! While t' model was stable with a B6-0/A8-5 combination, me bucko, it be nay stable with a B6-0/B6-6. Aye aye! At t' sustainer ignition, it looped. Ahoy! It was in t' air at ejection, no damage.

Summary:
PROs: I be happy with t' finished look o' t' model. Avast! Avast! Visually, t' descendin' rings and painted black band give t' impression o' a conical stabilized rocket. Well, blow me down! While t' model is only two-stage, matey, it looks more like a three stager. Begad! Avast, me proud beauty! New designs can present construction and stabilization issues, matey, but if you glean a few new lessons in t' process it's all worthwhile.

CONs: Even with all t' fins and tubing, t' model required nose weight t' be stable. Begad! It was stable for t' second flight after addin' nose weight. Aye aye! Avast, me proud beauty! It was nay stable for t' third and final flight.