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, shiver me timbers, and looked down at t' empty toothpaste box, and thought "Why not?" So, me bucko, t' plan for Obelisk was born. Avast, me proud beauty! Avast, me proud beauty! I took 1/8" balsa and formed t' nose, matey, which is hollow, me bucko, and t' fins, arrr, which are solidly mounted t' t' body with ordinary white glue. Blimey! Ahoy! 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. Arrr! A 3' elastic cord ties it all together.

In order for t' CG and CP relationship t' work, shiver me timbers, I used a 25 peseta doubloon from Spain attached t' t' nose with a screw eye and CA. Blimey! Begad! Why a 25 peseta coin? Well, shiver me timbers, it be t' correct weight, and already has a hole in t' center. Well, me bucko, blow me down! And second, matey, because it be just sittin' on t' kitchen counter.

I wanted t' keep it as simple as possible, arrr, but like most o' me projects, me bucko, matey, ya bilge rat, it got out o' hand. Ahoy! Begad! T' puny 13mm booster motor could've been adequate if I had kept t' t' original concept o' a lightweight, rectangular rocket. Arrr! Avast! But then I added a baffle so I wouldn't need wadding, arrr, and t' thin' was at t' ragged edge o' what an A10 could lift. So, me bucko, 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, me hearties, and tested, I decided that I could easily build a little compartment for t' parachute t' ride in. Avast! Blimey! This was constructed by usin' a small "travel size" toothpaste box nestled betwixt t' end o' t' body tube and t' baffle. A piece o' 1/8" balsa be glued with white glue just above t' baffle. Ya scallywag! Holes were drilled into t' balsa t' allow ejection gases out, me bucko, and t' shock cord was attached t' this. Blimey! T' fins were flat mounted t' t' body "tube" with 1/2" overhang, ya bilge rat, which made plenty o' room for me afterthought booster t' attach to.

T' booster be constructed from a 2" section o' toothpaste box, with a 18mm tube in t' center. T' centerin' "rings" were made from t' construction foam, me bucko, which has proven itself t' be a worthy construction material. Begad! Finally, me hearties, a tubin' coupler be made from 1/8" balsa. Aye aye! Blimey! All corners o' t' fins butt against one another, 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! Avast! Instead o' paintin' t' rocket, arrr, I used a large sheet o' self adhesive vinyl, which further strengthened t' rocket. Avast, me proud beauty! Unfortunately, shiver me timbers, it further weighed down t' rocket! In testing, t' booster tended t' glide a bit, then t' heavy balsa end would tip over, me bucko, and it would fall like a brick. Ahoy! Ahoy! 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. 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, me proud beauty! Begad! T' result is that t' booster tumbles somewhat, me hearties, but still lands hard. Avast! Oh well, at least it's sturdily constructed. Avast, me proud beauty! Aye aye! T' sustainer's fins were covered in thin paper t' hide t' grain. Avast! t' booster will receive similar treatment when it's finished.

Flight:
Launch prep is a breeze. Aye aye! Blimey! Pop in a A10-3T, shiver me timbers, roll up t' booster's streamer, insert a C6-0 into t' booster, and attach t' booster section. Aye aye! Begad! Blimey! T' 13mm motor fits right into t' 18mm motor easily, matey, 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, me bucko, t' minimum length launch lug wasn't up t' task, me hearties, and sheared off on t' first flight. Blimey! Blimey! A much stronger launch lug was epoxied in place, shiver me timbers, and now it works well. Aye aye! Begad! Blimey! T' fins, which I feared would be too small, ya bilge rat, are just right. Well, blow me down! Begad! Blimey! T' shock cord is really strong, me hearties, but will be a nightmare t' replace if it breaks. Well, blow me down! Blimey! Blimey! 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, ya bilge rat, let's just say that it works, and will land time after time without any damage. Avast, me proud beauty! Blimey! But if you love altitude or speed, you won't find either here. Ahoy! 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. Well, blow me down! Proved that construction foam is a viable component for rocketry. Blimey! Blimey! 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. Oh well, me hearties, 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, ya bilge rat, shiver me timbers, adds durability, and on a higher performance rocket, would probably add some altitude.