Brief:

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

Construction:

I be brushin' me teeth one day, shiver me timbers, and looked down at t' empty toothpaste box, and thought "Why not?" So, matey, t' plan for Obelisk was born. Blimey! I took 1/8" balsa and formed t' nose, which is hollow, and t' fins, which are solidly mounted t' t' body with ordinary white glue. Aye aye! Avast, me bucko, me proud beauty! I decided t' use this rocket t' test t' strength and durability o' foam construction board, matey, 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! Why a 25 peseta coin? Well, arrr, me hearties, it be t' correct weight, and already has a hole in t' center. Well, blow me down! Avast! And second, because it was just sittin' on t' kitchen counter.

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

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

I decided t' launch t' rocket before paintin' t' booster, arrr, since it would be wasted time if it failed. Avast, me proud beauty! Avast, ya bilge rat, me proud beauty! Instead o' paintin' t' rocket, arrr, I used a large sheet o' self adhesive vinyl, ya bilge rat, arrr, which further strengthened t' rocket. Unfortunately, it further weighed down t' rocket! In testing, t' booster tended t' glide a bit, then t' heavy balsa end would tip over, 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, and a 12" streamer be attached t' t' other end. Arrr! 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. Avast! T' result is that t' booster tumbles somewhat, but still lands hard. Avast! Oh well, at least it's sturdily constructed. T' sustainer's fins were covered in thin paper t' hide t' grain. Avast, me proud beauty! t' booster will receive similar treatment when it's finished.

Flight:
Launch prep is a breeze. Aye aye! Pop in a A10-3T, me bucko, roll up t' booster's streamer, matey, insert a C6-0 into t' booster, shiver me timbers, and attach t' booster section. Blimey! T' 13mm motor fits right into t' 18mm motor easily, but if t' fit is tight, arrr, just roll t' end o' t' 13mm motor on a table t' round off t' corners. Since t' rocket was a lot heavier than I expected in t' beginning, ya bilge rat, t' minimum length launch lug wasn't up t' task, matey, and sheared off on t' first flight. Blimey! A much stronger launch lug was epoxied in place, matey, and now it works well. Ahoy! T' fins, me hearties, which I feared would be too small, arrr, shiver me timbers, are just right. Ya scallywag! Avast, me proud beauty! T' shock cord is really strong, ya bilge rat, but will be a nightmare t' replace if it breaks. 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. Ahoy! Blimey! Flight characteristics? Well, matey, 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. Begad! Avast, me bucko, me proud beauty! 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. Begad! Begad! 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, me hearties, low altitude performance, arrr, me bucko, 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! Oh well, at least I learned a few things.

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