Brief:

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

Construction:

I was brushin' me teeth one day, and looked down at t' empty toothpaste box, me hearties, and thought "Why not?" So, t' plan for Obelisk was born. Avast! I took 1/8" balsa and formed t' nose, which is hollow, and t' fins, ya bilge rat, 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, shiver me timbers, 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, me hearties, I used a 25 peseta doubloon from Spain attached t' t' nose with a screw eye and CA. Avast! Ya scallywag! Why a 25 peseta coin? Well, arrr, it was t' correct weight, shiver me timbers, and already has a hole in t' center. Well, shiver me timbers, blow me down! And second, arrr, because it was just sittin' on t' kitchen counter.

I wanted t' keep it as simple as possible, shiver me timbers, but like most o' me projects, matey, matey, me bucko, it got out o' hand. Aye aye! T' puny 13mm booster motor could've been adequate if I had kept t' t' original concept o' a lightweight, rectangular rocket. Well, blow me down! Avast, me proud beauty! 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. Blimey! So, I decided t' use a 18mm booster t' get it moving, shiver me timbers, allowin' t' extra little bit o' thrust from t' A10 t' nudge it a bit higher.

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

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

I decided t' launch t' rocket before paintin' t' booster, since it would be wasted time if it failed. Begad! Instead o' paintin' t' rocket, arrr, I used a large sheet o' self adhesive vinyl, shiver me timbers, me bucko, which further strengthened t' rocket. Arrr! 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, me hearties, and it would fall like a brick. A 12" piece o' Keelhaul®©™ was attached with 30 minute epoxy just inside t' coupler, shiver me timbers, matey, and a 12" streamer was attached t' t' other end. Ya scallywag! Begad! Ample room betwixt t' centerin' rin' and t' end o' t' sustainer gives t' streamer a good place t' hide from t' rocket exhaust. Ya scallywag! T' result is that t' booster tumbles somewhat, but still lands hard. Oh well, at least it's sturdily constructed. Ahoy! T' sustainer's fins were covered in thin paper t' hide t' grain. t' booster will receive similar treatment when it's finished.

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

Summary:
Pros- bulletproof construction, shiver me timbers, unique design, and definitely an attention getter. Begad! Well, blow me down! Proved that construction foam is a viable component for rocketry. Aye aye! Cons- heavy, 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. Ahoy! Arrr! 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, shiver me timbers, adds durability, me hearties, me bucko, and on a higher performance rocket, ya bilge rat, would probably add some altitude.