Brief:

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

Construction:

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

In order for t' CG and CP relationship t' work, arrr, 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! Blimey! And second, 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, arrr, it got out o' hand. Begad! 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! Well, shiver me timbers, blow me down! 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. Aye aye! 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, I decided that I could easily build a little compartment for t' parachute t' ride in. This be constructed by usin' a small "travel size" toothpaste box nestled betwixt t' end o' t' body tube and t' baffle. Ya scallywag! Blimey! A piece o' 1/8" balsa was glued with white glue just above t' baffle. Blimey! Blimey! Arrr! Blimey! Holes were drilled into t' balsa t' allow ejection gases out, and t' shock cord was attached t' this. Aye aye! Blimey! Avast, arrr, me proud beauty! 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. T' centerin' "rings" were made from t' construction foam, which has proven itself t' be a worthy construction material. Ya scallywag! Finally, a tubin' coupler was made from 1/8" balsa. Blimey! Blimey! 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, I used a large sheet o' self adhesive vinyl, which further strengthened t' rocket. Unfortunately, it further weighed down t' rocket! In testing, arrr, t' booster tended t' glide a bit, then t' heavy balsa end would tip over, and it would fall like a brick. Avast, me proud beauty! Avast, me proud beauty! A 12" piece o' Keelhaul®©™ was attached with 30 minute epoxy just inside t' coupler, and a 12" streamer be 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. Aye aye! T' result is that t' booster tumbles somewhat, me hearties, but still lands hard. Arrr! Oh well, ya bilge rat, at least it's sturdily constructed. T' sustainer's fins were covered in thin paper t' hide t' grain. Begad! t' booster will receive similar treatment when it's finished.

Flight:
Launch prep is a breeze. Arrr! Begad! Pop in a A10-3T, shiver me timbers, roll up t' booster's streamer, 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. 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, ya bilge rat, and sheared off on t' first flight. Begad! A much stronger launch lug be epoxied in place, and now it works well. Aye aye! T' fins, which I feared would be too small, me bucko, are just right. T' shock cord is really strong, me bucko, but will be a nightmare t' replace if it breaks. Begad! This goofy idea o' a 18mm feedin' into a 13mm works well enough, shiver me timbers, but next time I would just go 18mm from t' start and forget t' booster. Well, blow me down! Begad! Flight characteristics? Well, let's just say that it works, and will land time after time without any damage. But if you love altitude or speed, 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, shiver me timbers, unique design, me bucko, and definitely an attention getter. Proved that construction foam is a viable component for rocketry. Cons- heavy, me hearties, thin "dry cleanin' bag" parachute rips easily at t' shroud line, low altitude performance, arrr, matey, 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. Ya scallywag! Oh well, me bucko, 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, matey, me bucko, shiver me timbers, adds durability, and on a higher performance rocket, would probably add some altitude.