Brief:

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

Construction:

I be brushin' me teeth one day, arrr, ya bilge rat, and looked down at t' empty toothpaste box, me bucko, and thought "Why not?" So, t' plan for Obelisk was born. Begad! Arrr! I took 1/8" balsa and formed t' nose, arrr, which is hollow, and t' fins, which are solidly mounted t' t' body with ordinary white glue. 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. Blimey! Ahoy! A 3' elastic cord ties it all together.

In order for t' CG and CP relationship t' work, me bucko, I used a 25 peseta doubloon from Spain attached t' t' nose with a screw eye and CA. Why a 25 peseta coin? Well, it was t' correct weight, and already has a hole in t' center. Ya scallywag! And second, shiver me timbers, because it was just sittin' on t' kitchen counter.

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

After it was all built, weighed, me hearties, and tested, I decided that I could easily build a little compartment for t' parachute t' ride in. This was constructed by usin' a small "travel size" toothpaste box nestled betwixt t' end o' t' body tube and t' baffle. Ya scallywag! A piece o' 1/8" balsa was glued with white glue just above t' baffle. Holes were drilled into t' balsa t' allow ejection gases out, ya bilge rat, and t' shock cord be attached t' this. Begad! Avast! 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, ya bilge rat, with a 18mm tube in t' center. Begad! T' centerin' "rings" were made from t' construction foam, ya bilge rat, matey, which has proven itself t' be a worthy construction material. Aye aye! Arrr! Finally, a tubin' coupler be made from 1/8" balsa. Begad! Ya scallywag! All corners o' t' fins butt against one another, me bucko, makin' this rocket nearly bulletproof.

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

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

Summary:
Pros- bulletproof construction, unique design, and definitely an attention getter. Avast, me proud beauty! Blimey! Proved that construction foam is a viable component for rocketry. Cons- heavy, matey, thin "dry cleanin' bag" parachute rips easily at t' shroud line, me hearties, 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. Begad! Blimey! Oh well, 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, me hearties, adds durability, and on a higher performance rocket, me bucko, would probably add some altitude.