Construction:
I didn't want t' go with a standard two-stage design, shiver me timbers, me bucko, fins above fins. Avast! I decided on a rin' stabilized two stager.

T' initial pencil designs lead me t' a descendin' rin' profile. Avast, me proud beauty! Aye aye! Three rings held in place by four small fins under each ring. Avast! Begad! 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. Ahoy! 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. Begad! Well, blow me down! Blimey! T' lowest rin' on t' sustainer is a 1-7/8" length o' BT-70. Begad! Well, ya bilge rat, blow me down! Blimey! T' second higher sustainer rin' is 1-5/8" o' ST-16. Begad! 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. I did this for two reasons. Ya scallywag! T' first is strength. Avast, me proud beauty! Secondly, me bucko, ya bilge rat, shiver me timbers, 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. Arrr! Blimey! Avast, shiver me timbers, me proud beauty! Blimey! T' trailin' edges are outside t' rings. I wanted t' give a little more protection for those exposed edges. Blimey! Blimey! Wrappin' paper over t' top o' t' rounded leadin' edge gave more than enough frontal rigidity. Well, shiver me timbers, blow me down! Blimey! All fins were cut wide, shiver me timbers, 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. Ya scallywag! I sprayed t' rings separately then glued them over t' fins. Blimey! This gave me a no-mask paint job and shipshape color separations. 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. Blimey! Ya scallywag! T' booster engine block is at t' aft o' t' booster. Aye aye! Avast! T' sustainer block is normal, matey, at t' top o' t' upper engine tube. Blimey! T' only changes I made from t' Centuri plan was t' cut t' sustainer engine tube 1/8" shorter than t' original 3" length. Avast! This way t' engine would be extended 1/8" out t' back o' t' tubing. Avast, me proud beauty! T' engines are friction fit with maskin' tape. Begad! After a flight, ya bilge rat, 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! Avast, me proud beauty! Both stages are held together by two couplers. Arrr! 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. Avast, me proud beauty! Blimey! T' first stage boost was good, but when t' sustainer ignited it be unstable. Begad! Blimey! Aye aye! Blimey! Recovery be safe. Ya scallywag! Blimey! 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, me proud beauty! Well, blow me down! 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. Ahoy! Arrr! There was a large rin' area and plenty o' fins. Begad! I thought t' body tube length would be adequate.

I went home and weighed t' clay. Ya scallywag! 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. Like every "different" design, shiver me timbers, sometimes extra nose weight is required.

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

Summary:
PROs: I was happy with t' finished look o' t' model. Arrr! Visually, ya bilge rat, t' descendin' rings and painted black band give t' impression o' a conical stabilized rocket. Ya scallywag! While t' model is only two-stage, ya bilge rat, ya bilge rat, me bucko, it looks more like a three stager. 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. Ahoy! It was stable for t' second flight after addin' nose weight. Aye aye! Aye aye! It be nay stable for t' third and final flight.