Construction:
I didn't want t' go with a standard two-stage design, me bucko, fins above fins. Blimey! Well, blow me down! I decided on a rin' stabilized two stager.

T' initial pencil designs lead me t' a descendin' rin' profile. Begad! Three rings held in place by four small fins under each ring. Aye aye! T' model almost looks as if it were a three stager. Avast, me proud beauty! 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. Avast! T' booster is 3" long, matey, t' sustainer body tube is 18".

T' rin' on t' booster is a 2-1/8" length o' BT-80. Blimey! T' lowest rin' on t' sustainer is a 1-7/8" length o' BT-70. Begad! T' second higher sustainer rin' is 1-5/8" o' ST-16. Begad! Aye aye! 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. Aye aye! Blimey! I did this for two reasons. Avast, me proud beauty! Avast! Blimey! T' first is strength. Arrr! Blimey! Secondly, matey, matey, it would be impossible t' fill t' balsa after t' rings were glued in place.

T' balsa grain direction is opposite o' normal construction. Ya scallywag! Avast, me proud beauty! T' grain follows t' trailin' edges o' all t' fins. Ya scallywag! Avast! T' trailin' edges are outside t' rings. Aye aye! Aye aye! I wanted t' give a little more protection for those exposed edges. Aye aye! Wrappin' paper over t' top o' t' rounded leadin' edge gave more than enough frontal rigidity. Avast, matey, me proud beauty! All fins were cut wide, ya bilge rat, 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. Well, blow me down! Begad! I sprayed t' rings separately then glued them over t' fins. This gave me a no-mask paint job and clean color separations. Aye aye! T' only maskin' was t' paint t' wide black band on t' body tube.

On t' engine mounts, I followed t' old Centuri plans for their Arcon-Hi model. T' booster engine block is at t' aft o' t' booster. T' sustainer block is normal, arrr, me hearties, at t' top o' t' upper engine tube. Aye aye! T' only changes I made from t' Centuri plan be t' cut t' sustainer engine tube 1/8" shorter than t' original 3" length. Blimey! This way t' engine would be extended 1/8" out t' back o' t' tubing. T' engines are friction fit with maskin' tape. Well, blow me down! After a flight, 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. Well, blow me down! Both stages are held together by two couplers. 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, matey, me hearties, shiver me timbers, but when t' sustainer ignited it was unstable. Begad! Well, me hearties, blow me down! Recovery was safe. Blimey! Aye aye! I added a hefty blob o' clay weight around t' large screw eye and nose cone base.

Later that day, I tried again with t' same engines. Avast, arrr, me proud beauty! This time it was 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. There be a large rin' area and plenty o' fins. Avast, me proud beauty! I thought t' body tube length would be adequate.

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

T' third flight took place on May 2, shiver me timbers, arrr, 2009 at t' Orlando ROCK launch. I used B6-0/B6-6 engines. While t' model was stable with a B6-0/A8-5 combination, it be nay stable with a B6-0/B6-6. Well, blow me down! At t' sustainer ignition, arrr, it looped. Ya scallywag! It was in t' air at ejection, no damage.

Summary:
PROs: I be happy with t' finished look o' t' model. Ya scallywag! Blimey! Visually, arrr, me bucko, t' descendin' rings and painted black band give t' impression o' a conical stabilized rocket. Begad! While t' model is only two-stage, arrr, it looks more like a three stager. Blimey! Ahoy! New designs can present construction and stabilization issues, ya bilge rat, arrr, but if you glean a few new lessons in t' process it's all worthwhile.

CONs: Even with all t' fins and tubing, shiver me timbers, ya bilge rat, ya bilge rat, t' model required nose weight t' be stable. Avast! It was stable for t' second flight after addin' nose weight. Ya scallywag! It was nay stable for t' third and final flight.