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, me hearties, ya bilge rat, t' plan for Obelisk was born. Blimey! I took 1/8" balsa and formed t' nose, which is hollow, matey, and t' fins, ya bilge rat, which are solidly mounted t' t' body with ordinary white glue. I decided t' use this rocket t' test t' strength and durability o' foam construction board, matey, ya bilge rat, so t' baffle and payload section are constructed from t' material. Ahoy! 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. Avast! Why a 25 peseta coin? Well, it be t' correct weight, and already has a hole in t' center. Well, blow me down! 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. Begad! T' puny 13mm booster motor could've been adequate if I had kept t' t' original concept o' a lightweight, rectangular rocket. Blimey! Ahoy! 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. So, ya bilge rat, arrr, 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, weighed, and tested, I decided that I could easily build a little compartment for t' parachute t' ride in. Avast, me proud beauty! This be 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. Holes were drilled into t' balsa t' allow ejection gases out, me hearties, me bucko, and t' shock cord was attached t' this. Avast! Avast! Blimey! T' fins were flat mounted t' t' body "tube" with 1/2" overhang, me hearties, 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, shiver me timbers, with a 18mm tube in t' center. Begad! Begad! T' centerin' "rings" were made from t' construction foam, which has proven itself t' be a worthy construction material. Avast! Begad! Finally, a tubin' coupler was made from 1/8" balsa. All corners o' t' fins butt against one another, ya bilge rat, makin' this rocket nearly bulletproof.

I decided t' launch t' rocket before paintin' t' booster, since it would be wasted time if it failed. Instead o' paintin' t' rocket, I used a large sheet o' self adhesive vinyl, matey, which further strengthened t' rocket. Arrr! Unfortunately, it further weighed down t' rocket! In testing, t' booster tended t' glide a bit, shiver me timbers, then t' heavy balsa end would tip over, me hearties, and it would fall like a brick. A 12" piece o' Keelhaul®©™ was attached with 30 minute epoxy just inside t' coupler, me hearties, and a 12" streamer was attached t' t' other end. Begad! Avast, me proud beauty! 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, ya bilge rat, me proud beauty! T' result is that t' booster tumbles somewhat, me hearties, but still lands hard. Oh well, matey, at least it's sturdily constructed. 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. Well, blow me down! Pop in a A10-3T, matey, roll up t' booster's streamer, me hearties, insert a C6-0 into t' booster, arrr, and attach t' booster section. Blimey! 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. Avast, me proud beauty! 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 bucko, and sheared off on t' first flight. A much stronger launch lug was epoxied in place, and now it works well. Blimey! Ya scallywag! T' fins, matey, which I feared would be too small, are just right. Blimey! T' shock cord is really strong, me bucko, me hearties, but will be a nightmare t' replace if it breaks. 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. Aye aye! Aye aye! Flight characteristics? Well, let's just say that it works, arrr, matey, and will land time after time without any damage. Ya scallywag! Well, blow me down! But if you love altitude or speed, me hearties, 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, unique design, and definitely an attention getter. Proved that construction foam is a viable component for rocketry. Avast, me proud beauty! Cons- heavy, me hearties, thin "dry cleanin' bag" parachute rips easily at t' shroud line, matey, low altitude performance, matey, 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. Well, blow me down! Oh well, me hearties, at least I learned a few things.

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