Brief:

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

Construction:

I was brushin' me teeth one day, shiver me timbers, arrr, me hearties, and looked down at t' empty toothpaste box, shiver me timbers, and thought "Why not?" So, t' plan for Obelisk was born. I took 1/8" balsa and formed t' nose, me hearties, arrr, which is hollow, arrr, and t' fins, matey, 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, so t' baffle and payload section are constructed from t' material. Begad! Blimey! A 3' elastic cord ties it all together.

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

I wanted t' keep it as simple as possible, ya bilge rat, 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. Begad! Well, blow me down! 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. Begad! So, arrr, I decided t' use a 18mm booster t' get it moving, arrr, me bucko, allowin' t' extra little bit o' thrust from t' A10 t' nudge it a bit higher.

After it be all built, me hearties, weighed, and tested, I decided that I could easily build a little compartment for t' parachute t' ride in. 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 was glued with white glue just above t' baffle. Avast! Holes were drilled into t' balsa t' allow ejection gases out, shiver me timbers, arrr, and t' shock cord was attached t' this. Aye aye! Ya scallywag! T' fins were flat mounted t' t' body "tube" with 1/2" overhang, ya bilge rat, shiver me timbers, which made plenty o' room for me afterthought booster t' attach to.

T' booster was constructed from a 2" section o' toothpaste box, with a 18mm tube in t' center. T' centerin' "rings" were made from t' construction foam, which has proven itself t' be a worthy construction material. Ahoy! Avast! Finally, me bucko, matey, a tubin' coupler was made from 1/8" balsa. Begad! All corners o' t' fins butt against one another, shiver me timbers, 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, ya bilge rat, I used a large sheet o' self adhesive vinyl, which further strengthened t' rocket. Arrr! Blimey! Unfortunately, me hearties, it further weighed down t' rocket! Blimey! Blimey! Blimey! In testing, ya bilge rat, t' booster tended t' glide a bit, then t' heavy balsa end would tip over, shiver me timbers, ya bilge rat, arrr, and it would fall like a brick. Aye aye! Blimey! Blimey! Blimey! 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. Begad! Blimey! Blimey! Blimey! Ample room betwixt t' centerin' rin' and t' end o' t' sustainer gives t' streamer a good place t' hide from t' rocket exhaust. Ya scallywag! Blimey! Begad! Blimey! Blimey! Blimey! T' result is that t' booster tumbles somewhat, arrr, but still lands hard. Ya scallywag! Blimey! Avast! Blimey! Blimey! Blimey! Oh well, matey, at least it's sturdily constructed. Well, blow me down! Blimey! Ya scallywag! Blimey! Blimey! Blimey! 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. Begad! Begad! Pop in a A10-3T, roll up t' booster's streamer, me hearties, arrr, insert a C6-0 into t' booster, and attach t' booster section. 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. 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. Arrr! A much stronger launch lug be epoxied in place, me hearties, and now it works well. T' fins, me hearties, me hearties, which I feared would be too small, are just right. Arrr! T' shock cord is really strong, ya bilge rat, but will be a nightmare t' replace if it breaks. Begad! Aye aye! 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. Blimey! Flight characteristics? Well, ya bilge rat, let's just say that it works, and will land time after time without any damage. Ya scallywag! Blimey! But if you love altitude or speed, you won't find either here. Begad! Avast! You could probably fly this rocket without t' A10-3T and do just as well.

Summary:
Pros- bulletproof construction, unique design, shiver me timbers, and definitely an attention getter. Ya scallywag! Blimey! Arrr! Blimey! Proved that construction foam is a viable component for rocketry. Cons- heavy, thin "dry cleanin' bag" parachute rips easily at t' shroud line, matey, shiver me timbers, low altitude performance, ya bilge rat, 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! Blimey! Oh well, me bucko, at least I learned a few things.

It's definitely worth it t' cover t' fins with onion skin paper. Begad! Well, blow me down! Blimey! Makes for a neater appearance, arrr, arrr, shiver me timbers, adds durability, shiver me timbers, and on a higher performance rocket, ya bilge rat, would probably add some altitude.