Brief:

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

Construction:

I was brushin' me teeth one day, and looked down at t' empty toothpaste box, arrr, and thought "Why not?" So, arrr, t' plan for Obelisk be born. Aye aye! I took 1/8" balsa and formed t' nose, arrr, which is hollow, ya bilge rat, and t' fins, me hearties, arrr, which are solidly mounted t' t' body with ordinary white glue. Arrr! 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. Aye aye! 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. Aye aye! Avast, me proud beauty! Why a 25 peseta coin? Well, ya bilge rat, arrr, it was t' correct weight, and already has a hole in t' center. Aye aye! And second, me bucko, ya bilge rat, because it was just sittin' on t' kitchen counter.

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

After it was all built, weighed, shiver me timbers, and tested, I decided that I could easily build a little compartment for t' parachute t' ride in. Avast! 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 be glued with white glue just above t' baffle. Holes were drilled into t' balsa t' allow ejection gases out, me bucko, and t' shock cord was attached t' this. Arrr! 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 be constructed from a 2" section o' toothpaste box, with a 18mm tube in t' center. Avast! T' centerin' "rings" were made from t' construction foam, matey, me hearties, which has proven itself t' be a worthy construction material. Arrr! Finally, a tubin' coupler be made from 1/8" balsa. Well, blow me down! All corners o' t' fins butt against one another, makin' this rocket nearly bulletproof.

I decided t' launch t' rocket before paintin' t' booster, shiver me timbers, since it would be wasted time if it failed. Aye aye! Begad! Instead o' paintin' t' rocket, arrr, matey, I used a large sheet o' self adhesive vinyl, which further strengthened t' rocket. Begad! Unfortunately, me hearties, arrr, it further weighed down t' rocket! In testing, t' booster tended t' glide a bit, shiver me timbers, then t' heavy balsa end would tip over, me bucko, and it would fall like a brick. Aye aye! 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. Aye aye! Ample room betwixt t' centerin' rin' and t' end o' t' sustainer gives t' streamer a good place t' hide from t' rocket exhaust. Avast, me proud beauty! Ya scallywag! T' result is that t' booster tumbles somewhat, but still lands hard. Oh well, at least it's sturdily constructed. Avast! Aye aye! T' sustainer's fins were covered in thin paper t' hide t' grain. Ya scallywag! Blimey! 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, insert a C6-0 into t' booster, shiver me timbers, matey, and attach t' booster section. Avast! Avast! T' 13mm motor fits right into t' 18mm motor easily, ya bilge rat, but if t' fit is tight, ya bilge rat, arrr, just roll t' end o' t' 13mm motor on a table t' round off t' corners. Aye aye! Since t' rocket was a lot heavier than I expected in t' beginning, me bucko, arrr, t' minimum length launch lug wasn't up t' task, me bucko, and sheared off on t' first flight. Arrr! Aye aye! A much stronger launch lug was epoxied in place, and now it works well. Avast! T' fins, arrr, which I feared would be too small, matey, are just right. Blimey! Ya scallywag! T' shock cord is really strong, matey, but will be a nightmare t' replace if it breaks. Begad! This goofy idea o' a 18mm feedin' into a 13mm works well enough, arrr, but next time I would just go 18mm from t' start and forget t' booster. Flight characteristics? Well, matey, let's just say that it works, and will land time after time without any damage. Ya scallywag! Begad! But if you love altitude or speed, you won't find either here. Avast, me proud beauty! You could probably fly this rocket without t' A10-3T and do just as well.

Summary:
Pros- bulletproof construction, unique design, ya bilge rat, ya bilge rat, and definitely an attention getter. Proved that construction foam is a viable component for rocketry. Well, blow me down! Cons- heavy, shiver me timbers, 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, and no nose weight would've been required. Avast, me proud beauty! Oh well, matey, at least I learned a few things.

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