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

T' initial pencil designs lead me t' a descendin' rin' profile. Avast, me proud beauty! Three rings held in place by four small fins under each ring. Avast, me proud beauty! 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 was built around a ST-10 airframe. Ya scallywag! T' booster is 3" long, ya bilge rat, 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. Avast! Ya scallywag! Blimey! T' second higher sustainer rin' is 1-5/8" o' ST-16. 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. Avast, me proud beauty! I did this for two reasons. Begad! Avast, ya bilge rat, me proud beauty! T' first is strength. Secondly, it would be impossible t' fill t' balsa after t' rings were glued in place.

T' balsa grain direction is opposite o' normal construction. Begad! 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. Begad! Wrappin' paper over t' top o' t' rounded leadin' edge gave more than enough frontal rigidity. 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. I sprayed t' rings separately then glued them over t' fins. Ya scallywag! Aye aye! This gave me a no-mask paint job and clean color separations. T' only maskin' was t' paint t' wide black band on t' body tube.

On t' engine mounts, arrr, I followed t' old Centuri plans for their Arcon-Hi model. Begad! Ya scallywag! T' booster engine block is at t' aft o' t' booster. Ahoy! 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. Ahoy! This way t' engine would be extended 1/8" out t' back o' t' tubing. Arrr! T' engines are friction fit with maskin' tape. Ahoy! 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. Avast, me proud beauty! Blimey! Blimey! Blimey! Both stages are held together by two couplers. Aye aye! Blimey! Blimey! Blimey! 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. Begad! T' first stage boost was good, arrr, but when t' sustainer ignited it be unstable. Arrr! Recovery be safe. Begad! Well, blow me down! 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. Aye aye! This time it was stable and had a straight boost with good stagin' and recovery.

I thought it would be stable, but I hadn't used RockSim yet. Ya scallywag! There was a large rin' area and plenty o' fins. Blimey! I thought t' body tube length would be adequate.

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

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

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

CONs: Even with all t' fins and tubing, me bucko, shiver me timbers, t' model required nose weight t' be stable. It was stable for t' second flight after addin' nose weight. Well, blow me down! It was nay stable for t' third and final flight.