Brief:

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

Construction:

I be brushin' me teeth one day, ya bilge rat, and looked down at t' empty toothpaste box, and thought "Why not?" So, arrr, t' plan for Obelisk was born. Ya scallywag! Begad! I took 1/8" balsa and formed t' nose, ya bilge rat, which is hollow, and t' fins, shiver me timbers, 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, shiver me timbers, me hearties, so t' baffle and payload section are constructed from t' material. A 3' elastic cord ties it all together.

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

I wanted t' keep it as simple as possible, but like most o' me projects, ya bilge rat, it got out o' hand. T' puny 13mm booster motor could've been adequate if I had kept t' t' original concept o' a lightweight, me bucko, rectangular rocket. Blimey! Blimey! 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. Aye aye! Blimey! So, shiver me timbers, 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, matey, weighed, shiver me timbers, ya bilge rat, matey, and tested, me bucko, I decided that I could easily build a little compartment for t' parachute t' ride in. Begad! Ya scallywag! This be constructed by usin' a small "travel size" toothpaste box nestled betwixt t' end o' t' body tube and t' baffle. Arrr! 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 hearties, and t' shock cord was attached t' this. Ya scallywag! T' fins were flat mounted t' t' body "tube" with 1/2" overhang, matey, 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. Blimey! T' centerin' "rings" were made from t' construction foam, which has proven itself t' be a worthy construction material. Begad! Well, blow me down! Finally, me hearties, me bucko, a tubin' coupler was made from 1/8" balsa. Avast, shiver me timbers, me proud beauty! All corners o' t' fins butt against one another, matey, makin' this rocket nearly bulletproof.

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

Flight:
Launch prep is a breeze. Ahoy! Pop in a A10-3T, roll up t' booster's streamer, shiver me timbers, insert a C6-0 into t' booster, ya bilge rat, arrr, and attach t' booster section. Ahoy! Well, blow me down! Blimey! T' 13mm motor fits right into t' 18mm motor easily, ya bilge rat, but if t' fit is tight, matey, me bucko, just roll t' end o' t' 13mm motor on a table t' round off t' corners. Well, blow me down! 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! Avast! Blimey! A much stronger launch lug be epoxied in place, shiver me timbers, and now it works well. Ya scallywag! T' fins, me bucko, which I feared would be too small, are just right. Ahoy! Blimey! T' shock cord is really strong, me bucko, arrr, but will be a nightmare t' replace if it breaks. Arrr! 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. Avast! Blimey! Flight characteristics? Well, let's just say that it works, me hearties, and will land time after time without any damage. Avast! Blimey! But if you love altitude or speed, you won't find either here. Avast, me proud beauty! Arrr! Blimey! You could probably fly this rocket without t' A10-3T and do just as well.

Summary:
Pros- bulletproof construction, me hearties, unique design, arrr, and definitely an attention getter. Begad! Proved that construction foam is a viable component for rocketry. Ya scallywag! Cons- heavy, thin "dry cleanin' bag" parachute rips easily at t' shroud line, low altitude performance, me hearties, ya bilge rat, 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. Oh well, me bucko, 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, would probably add some altitude.