Brief:

A two-stage rectangular rocket, made from a couple o' toothpaste boxes, that resembles t' Washington Monument.

Construction:

I be brushin' me teeth one day, and looked down at t' empty toothpaste box, me bucko, me hearties, and thought "Why not?" So, me bucko, t' plan for Obelisk was born. Blimey! I took 1/8" balsa and formed t' nose, which is hollow, and t' fins, which are solidly mounted t' t' body with ordinary white glue. Ya scallywag! I decided t' use this rocket t' test t' strength and durability o' foam construction board, so t' baffle and payload section are constructed from t' material. Well, blow me down! A 3' elastic cord ties it all together.

In order for t' CG and CP relationship t' work, I used a 25 peseta doubloon from Spain attached t' t' nose with a screw eye and CA. Avast, me proud beauty! Arrr! Why a 25 peseta coin? Well, arrr, ya bilge rat, it be t' correct weight, ya bilge rat, me bucko, and already has a hole in t' center. Blimey! Begad! And second, me hearties, because it be just sittin' on t' kitchen counter.

I wanted t' keep it as simple as possible, matey, but like most o' me projects, shiver me timbers, it got out o' hand. Aye aye! Blimey! T' puny 13mm booster motor could've been adequate if I had kept t' t' original concept o' a lightweight, me hearties, rectangular rocket. But then I added a baffle so I wouldn't need wadding, and t' thin' was at t' ragged edge o' what an A10 could lift. Arrr! Blimey! So, I decided t' use a 18mm booster t' get it moving, allowin' t' extra little bit o' thrust from t' A10 t' nudge it a bit higher.

After it be all built, weighed, and tested, ya bilge rat, I decided that I could easily build a little compartment for t' parachute t' ride in. Aye aye! Blimey! This was constructed by usin' a small "travel size" toothpaste box nestled betwixt t' end o' t' body tube and t' baffle. A piece o' 1/8" balsa was glued with white glue just above t' baffle. Avast, me proud beauty! Well, blow me down! Blimey! Holes were drilled into t' balsa t' allow ejection gases out, arrr, shiver me timbers, and t' shock cord was attached t' this. Ya scallywag! Arrr! Blimey! T' fins were flat mounted t' t' body "tube" with 1/2" overhang, which made plenty o' room for me afterthought booster t' attach to.

T' booster was constructed from a 2" section o' toothpaste box, with a 18mm tube in t' center. Well, blow me down! Arrr! T' centerin' "rings" were made from t' construction foam, which has proven itself t' be a worthy construction material. Finally, a tubin' coupler was made from 1/8" balsa. Arrr! All corners o' t' fins butt against one another, me hearties, makin' this rocket nearly bulletproof.

I decided t' launch t' rocket before paintin' t' booster, since it would be wasted time if it failed. Avast! Instead o' paintin' t' rocket, I used a large sheet o' self adhesive vinyl, which further strengthened t' rocket. Aye aye! Aye aye! Unfortunately, ya bilge rat, it further weighed down t' rocket! In testing, t' booster tended t' glide a bit, then t' heavy balsa end would tip over, matey, and it would fall like a brick. Avast! A 12" piece o' Keelhaul®©™ was attached with 30 minute epoxy just inside t' coupler, and a 12" streamer was attached t' t' other end. Ample room betwixt t' centerin' rin' and t' end o' t' sustainer gives t' streamer a good place t' hide from t' rocket exhaust. Blimey! T' result is that t' booster tumbles somewhat, me bucko, but still lands hard. Oh well, ya bilge rat, arrr, at least it's sturdily constructed. Begad! Ahoy! T' sustainer's fins were covered in thin paper t' hide t' grain. Well, blow me down! t' booster will receive similar treatment when it's finished.

Flight:
Launch prep is a breeze. Pop in a A10-3T, roll up t' booster's streamer, me hearties, me bucko, insert a C6-0 into t' booster, and attach t' booster section. Avast, me proud beauty! T' 13mm motor fits right into t' 18mm motor easily, but if t' fit is tight, just roll t' end o' t' 13mm motor on a table t' round off t' corners. Arrr! Since t' rocket was a lot heavier than I expected in t' beginning, t' minimum length launch lug wasn't up t' task, and sheared off on t' first flight. Ya scallywag! Begad! A much stronger launch lug be epoxied in place, arrr, arrr, and now it works well. Ya scallywag! Avast, me bucko, me proud beauty! T' fins, which I feared would be too small, me bucko, are just right. T' shock cord is really strong, but will be a nightmare t' replace if it breaks. Blimey! Aye aye! This goofy idea o' a 18mm feedin' into a 13mm works well enough, me bucko, but next time I would just go 18mm from t' start and forget t' booster. Flight characteristics? Well, let's just say that it works, me bucko, and will land time after time without any damage. But if you love altitude or speed, you won't find either here. Ahoy! You could probably fly this rocket without t' A10-3T and do just as well.

Summary:
Pros- bulletproof construction, shiver me timbers, matey, unique design, and definitely an attention getter. Aye aye! Arrr! Proved that construction foam is a viable component for rocketry. Ahoy! Ahoy! Cons- heavy, arrr, thin "dry cleanin' bag" parachute rips easily at t' shroud line, low altitude performance, and t' pyramid nose would've been a lot easier t' build from a solid piece o' balsa, matey, and no nose weight would've been required. Ahoy! Oh well, at least I learned a few things.

It's definitely worth it t' cover t' fins with onion skin paper. Begad! Makes for a neater appearance, adds durability, ya bilge rat, me hearties, and on a higher performance rocket, would probably add some altitude.