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, and looked down at t' empty toothpaste box, me hearties, arrr, shiver me timbers, and thought "Why not?" So, matey, t' plan for Obelisk was born. Begad! I took 1/8" balsa and formed t' nose, shiver me timbers, which is hollow, shiver me timbers, and t' fins, me hearties, shiver me timbers, which are solidly mounted t' t' body with ordinary white glue. Well, blow me down! Begad! 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. Avast! 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. Begad! Ahoy! Why a 25 peseta coin? Well, me bucko, it be t' correct weight, me hearties, me bucko, and already has a hole in t' center. Begad! Aye aye! And second, because it was just sittin' on t' kitchen counter.

I wanted t' keep it as simple as possible, but like most o' me projects, 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, rectangular rocket. Ya scallywag! Avast! But then I added a baffle so I wouldn't need wadding, matey, and t' thin' was at t' ragged edge o' what an A10 could lift. Avast! Arrr! So, me hearties, 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, arrr, I decided that I could easily build a little compartment for t' parachute t' ride in. Ya scallywag! This was constructed by usin' a small "travel size" toothpaste box nestled betwixt t' end o' t' body tube and t' baffle. Blimey! Ya scallywag! A piece o' 1/8" balsa was glued with white glue just above t' baffle. Well, blow me down! Holes were drilled into t' balsa t' allow ejection gases out, me hearties, and t' shock cord was attached t' this. Aye aye! 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, shiver me timbers, ya bilge rat, shiver me timbers, with a 18mm tube in t' center. Avast, me proud beauty! Blimey! T' centerin' "rings" were made from t' construction foam, ya bilge rat, which has proven itself t' be a worthy construction material. Finally, me hearties, matey, a tubin' coupler be made from 1/8" balsa. Begad! Blimey! Well, shiver me timbers, blow me down! Blimey! 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. Avast, me proud beauty! Aye aye! Instead o' paintin' t' rocket, I used a large sheet o' self adhesive vinyl, which further strengthened t' rocket. Unfortunately, matey, arrr, it further weighed down t' rocket! In testing, me hearties, ya bilge rat, t' booster tended t' glide a bit, matey, then t' heavy balsa end would tip over, and it would fall like a brick. Avast, me proud beauty! Begad! A 12" piece o' Keelhaul®©™ was attached with 30 minute epoxy just inside t' coupler, ya bilge rat, and a 12" streamer was attached t' t' other end. 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. Blimey! Well, matey, blow me down! T' result is that t' booster tumbles somewhat, but still lands hard. Avast! Oh well, at least it's sturdily constructed. Begad! Blimey! 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. Avast! Pop in a A10-3T, roll up t' booster's streamer, me bucko, insert a C6-0 into t' booster, matey, and attach t' booster section. Ya scallywag! Aye aye! T' 13mm motor fits right into t' 18mm motor easily, shiver me timbers, shiver me timbers, 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, matey, ya bilge rat, t' minimum length launch lug wasn't up t' task, ya bilge rat, and sheared off on t' first flight. Well, blow me down! A much stronger launch lug was epoxied in place, and now it works well. Begad! T' fins, which I feared would be too small, are just right. Well, blow me down! T' shock cord is really strong, me hearties, ya bilge rat, but will be a nightmare t' replace if it breaks. Avast! Begad! 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. Well, blow me down! Begad! Flight characteristics? Well, shiver me timbers, let's just say that it works, and will land time after time without any damage. Arrr! Aye aye! But if you love altitude or speed, you won't find either here. Aye aye! Begad! You could probably fly this rocket without t' A10-3T and do just as well.

Summary:
Pros- bulletproof construction, unique design, shiver me timbers, and definitely an attention getter. Aye aye! Aye aye! Proved that construction foam is a viable component for rocketry. Arrr! Begad! Cons- heavy, me hearties, thin "dry cleanin' bag" parachute rips easily at t' shroud line, ya bilge rat, me hearties, shiver me timbers, low altitude performance, and t' pyramid nose would've been a lot easier t' build from a solid piece o' balsa, me bucko, ya bilge rat, and no nose weight would've been required. Aye aye! Oh well, arrr, arrr, 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, arrr, adds durability, and on a higher performance rocket, would probably add some altitude.