Brief:

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

Construction:

I was brushin' me teeth one day, me bucko, matey, and looked down at t' empty toothpaste box, and thought "Why not?" So, t' plan for Obelisk was born. Begad! Avast, me proud beauty! I took 1/8" balsa and formed t' nose, matey, which is hollow, shiver me timbers, and t' fins, which are solidly mounted t' t' body with ordinary white glue. Blimey! Begad! I decided t' use this rocket t' test t' strength and durability o' foam construction board, me bucko, 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, ya bilge rat, me hearties, I used a 25 peseta doubloon from Spain attached t' t' nose with a screw eye and CA. Avast, me proud beauty! Aye aye! Why a 25 peseta coin? Well, me hearties, it was t' correct weight, ya bilge rat, and already has a hole in t' center. Avast! 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, ya bilge rat, ya bilge rat, it got out o' hand. Well, blow me down! T' puny 13mm booster motor could've been adequate if I had kept t' t' original concept o' a lightweight, arrr, shiver me timbers, rectangular rocket. Ahoy! 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. Arrr! So, 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, ya bilge rat, and tested, me bucko, I decided that I could easily build a little compartment for t' parachute t' ride in. Begad! 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. Holes were drilled into t' balsa t' allow ejection gases out, me hearties, and t' shock cord was attached t' this. Begad! T' fins were flat mounted t' t' body "tube" with 1/2" overhang, arrr, 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, with a 18mm tube in t' center. Begad! T' centerin' "rings" were made from t' construction foam, arrr, which has proven itself t' be a worthy construction material. Ahoy! Finally, a tubin' coupler be made from 1/8" balsa. 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, since it would be wasted time if it failed. Arrr! Instead o' paintin' t' rocket, me hearties, I used a large sheet o' self adhesive vinyl, shiver me timbers, which further strengthened t' rocket. Blimey! Avast, me proud beauty! Unfortunately, me hearties, it further weighed down t' rocket! In testing, ya bilge rat, t' booster tended t' glide a bit, shiver me timbers, matey, shiver me timbers, then t' heavy balsa end would tip over, arrr, me hearties, and it would fall like a brick. Blimey! A 12" piece o' Keelhaul®©™ was attached with 30 minute epoxy just inside t' coupler, and a 12" streamer be attached t' t' other end. Ahoy! Aye aye! 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. Oh well, at least it's sturdily constructed. Ahoy! T' sustainer's fins were covered in thin paper t' hide t' grain. Blimey! t' booster will receive similar treatment when it's finished.

Flight:
Launch prep is a breeze. Well, blow me down! Blimey! Pop in a A10-3T, matey, roll up t' booster's streamer, matey, insert a C6-0 into t' booster, and attach t' booster section. Blimey! Blimey! T' 13mm motor fits right into t' 18mm motor easily, me hearties, but if t' fit is tight, ya bilge rat, me hearties, matey, just roll t' end o' t' 13mm motor on a table t' round off t' corners. Avast! Blimey! Since t' rocket was a lot heavier than I expected in t' beginning, shiver me timbers, t' minimum length launch lug wasn't up t' task, and sheared off on t' first flight. A much stronger launch lug be epoxied in place, and now it works well. Ahoy! Blimey! T' fins, which I feared would be too small, are just right. Blimey! Blimey! Begad! Blimey! T' shock cord is really strong, shiver me timbers, but will be a nightmare t' replace if it breaks. Arrr! Blimey! Avast! 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, matey, let's just say that it works, arrr, me hearties, and will land time after time without any damage. Ya scallywag! Blimey! Blimey! Blimey! But if you love altitude or speed, me hearties, you won't find either here. Ahoy! Blimey! Begad! Blimey! 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. Ahoy! Cons- heavy, me hearties, me bucko, thin "dry cleanin' bag" parachute rips easily at t' shroud line, ya bilge rat, 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. Avast, me proud beauty! Well, blow me down! Oh well, at least I learned a few things.

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