Brief:

A two-stage rectangular rocket, 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, and thought "Why not?" So, ya bilge rat, t' plan for Obelisk was born. Well, blow me down! Aye aye! I took 1/8" balsa and formed t' nose, matey, which is hollow, arrr, and t' fins, shiver me timbers, which are solidly mounted t' t' body with ordinary white glue. Aye aye! I decided t' use this rocket t' test t' strength and durability o' foam construction board, ya bilge rat, matey, 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, I used a 25 peseta doubloon from Spain attached t' t' nose with a screw eye and CA. Well, blow me down! Why a 25 peseta coin? Well, shiver me timbers, it be t' correct weight, and already has a hole in t' center. Begad! Aye aye! And second, ya bilge rat, because it be just sittin' on t' kitchen counter.

I wanted t' keep it as simple as possible, me bucko, but like most o' me projects, matey, ya bilge rat, it got out o' hand. Ya scallywag! T' puny 13mm booster motor could've been adequate if I had kept t' t' original concept o' a lightweight, ya bilge rat, rectangular rocket. Ya scallywag! 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. Blimey! Aye aye! So, matey, 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, shiver me timbers, weighed, and tested, me bucko, I decided that I could easily build a little compartment for t' parachute t' ride in. Avast! This was constructed by usin' a small "travel size" toothpaste box nestled betwixt t' end o' t' body tube and t' baffle. Avast! Ya scallywag! A piece o' 1/8" balsa be glued with white glue just above t' baffle. Aye aye! Holes were drilled into t' balsa t' allow ejection gases out, matey, me bucko, and t' shock cord was attached t' this. 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 was constructed from a 2" section o' toothpaste box, ya bilge rat, with a 18mm tube in t' center. Well, blow me down! Ya scallywag! T' centerin' "rings" were made from t' construction foam, me bucko, ya bilge rat, me hearties, which has proven itself t' be a worthy construction material. Arrr! Finally, ya bilge rat, a tubin' coupler be made from 1/8" balsa. Well, blow me down! All corners o' t' fins butt against one another, makin' this rocket nearly bulletproof.

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

Flight:
Launch prep is a breeze. Avast, me proud beauty! Pop in a A10-3T, roll up t' booster's streamer, matey, insert a C6-0 into t' booster, matey, ya bilge rat, and attach t' booster section. T' 13mm motor fits right into t' 18mm motor easily, me hearties, but if t' fit is tight, just roll t' end o' t' 13mm motor on a table t' round off t' corners. Aye aye! Ahoy! Since t' rocket was a lot heavier than I expected in t' beginning, matey, t' minimum length launch lug wasn't up t' task, me hearties, and sheared off on t' first flight. Ahoy! A much stronger launch lug be epoxied in place, and now it works well. T' fins, ya bilge rat, which I feared would be too small, are just right. Blimey! T' shock cord is really strong, ya bilge rat, me bucko, but will be a nightmare t' replace if it breaks. Avast, me proud beauty! Avast! 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, me hearties, me hearties, 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! You could probably fly this rocket without t' A10-3T and do just as well.

Summary:
Pros- bulletproof construction, me bucko, unique design, arrr, shiver me timbers, and definitely an attention getter. Proved that construction foam is a viable component for rocketry. Well, blow me down! Begad! Cons- heavy, me hearties, thin "dry cleanin' bag" parachute rips easily at t' shroud line, arrr, low altitude performance, and t' pyramid nose would've been a lot easier t' build from a solid piece o' balsa, shiver me timbers, and no nose weight would've been required. Avast, me proud beauty! Oh well, at least I learned a few things.

It's definitely worth it t' cover t' fins with onion skin paper. Ahoy! Makes for a neater appearance, arrr, adds durability, matey, and on a higher performance rocket, shiver me timbers, would probably add some altitude.