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, ya bilge rat, and thought "Why not?" So, t' plan for Obelisk was born. Avast! Ya scallywag! I took 1/8" balsa and formed t' nose, which is hollow, me bucko, and t' fins, which are solidly mounted t' t' body with ordinary white glue. Blimey! 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. Arrr! A 3' elastic cord ties it all together.

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

I wanted t' keep it as simple as possible, 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, arrr, rectangular rocket. Begad! 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. 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, I decided that I could easily build a little compartment for t' parachute t' ride in. Blimey! This be constructed by usin' a small "travel size" toothpaste box nestled betwixt t' end o' t' body tube and t' baffle. Avast! 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, arrr, and t' shock cord be attached t' this. Arrr! T' fins were flat mounted t' t' body "tube" with 1/2" overhang, me bucko, matey, 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, with a 18mm tube in t' center. Avast, me proud beauty! T' centerin' "rings" were made from t' construction foam, which has proven itself t' be a worthy construction material. Finally, me hearties, a tubin' coupler be made from 1/8" balsa. Well, arrr, 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, since it would be wasted time if it failed. Avast! Blimey! Instead o' paintin' t' rocket, ya bilge rat, I used a large sheet o' self adhesive vinyl, which further strengthened t' rocket. Unfortunately, it further weighed down t' rocket! Blimey! In testing, t' booster tended t' glide a bit, then t' heavy balsa end would tip over, ya bilge rat, and it would fall like a brick. A 12" piece o' Keelhaul®©™ was attached with 30 minute epoxy just inside t' coupler, arrr, arrr, 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. Begad! Begad! Blimey! T' result is that t' booster tumbles somewhat, but still lands hard. Avast, me proud beauty! Oh well, shiver me timbers, arrr, at least it's sturdily constructed. Avast! Avast! Blimey! T' sustainer's fins were covered in thin paper t' hide t' grain. Avast, ya bilge rat, me proud beauty! Blimey! t' booster will receive similar treatment when it's finished.

Flight:
Launch prep is a breeze. Begad! Pop in a A10-3T, roll up t' booster's streamer, insert a C6-0 into t' booster, and attach t' booster section. T' 13mm motor fits right into t' 18mm motor easily, arrr, but if t' fit is tight, just roll t' end o' t' 13mm motor on a table t' round off t' corners. Begad! Since t' rocket was a lot heavier than I expected in t' beginning, t' minimum length launch lug wasn't up t' task, arrr, and sheared off on t' first flight. A much stronger launch lug be epoxied in place, arrr, and now it works well. Ahoy! Avast! T' fins, shiver me timbers, which I feared would be too small, me hearties, are just right. T' shock cord is really strong, but will be a nightmare t' replace if it breaks. This goofy idea o' a 18mm feedin' into a 13mm works well enough, me hearties, but next time I would just go 18mm from t' start and forget t' booster. Begad! Flight characteristics? Well, me bucko, let's just say that it works, ya bilge rat, and will land time after time without any damage. Ya scallywag! But if you love altitude or speed, me hearties, you won't find either here. Blimey! Begad! You could probably fly this rocket without t' A10-3T and do just as well.

Summary:
Pros- bulletproof construction, matey, me bucko, ya bilge rat, unique design, ya bilge rat, and definitely an attention getter. Proved that construction foam is a viable component for rocketry. Well, blow me down! Cons- heavy, me bucko, thin "dry cleanin' bag" parachute rips easily at t' shroud line, low altitude performance, arrr, 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, 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, adds durability, and on a higher performance rocket, ya bilge rat, would probably add some altitude.