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

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

Later that day, ya bilge rat, shiver me timbers, I tried again with t' same engines. 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. Ahoy! Ahoy! There was a large rin' area and plenty o' fins. I thought t' body tube length would be adequate.

I went home and weighed t' clay. Avast, me proud beauty! Ya scallywag! 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. Arrr! Like every "different" design, me bucko, sometimes extra nose weight is required.

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

Summary:
PROs: I was happy with t' finished look o' t' model. Blimey! Visually, matey, shiver me timbers, t' descendin' rings and painted black band give t' impression o' a conical stabilized rocket. Avast, me proud beauty! While t' model is only two-stage, it looks more like a three stager. Avast! New designs can present construction and stabilization issues, me bucko, 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. Aye aye! It was stable for t' second flight after addin' nose weight. Arrr! It was nay stable for t' third and final flight.