Brief:
Aquafina is a tube-fin 24mm cluster rocket utilizing a fixed nose cone with a nose-mounted parachute mortar for recovery. The rocket was constructed at zero cost from an empty gift wrapping paper tube and the upper half of a bottled water ("Aquafina") PET plastic bottle. I wanted a good-flying yet "expendable" airframe to use in experiments for igniting Aerotech AP cluster motor arrays. Why a tube-fin design for this? -- they typically have CP so far aft that CG is easier to balance properly when heavy motor systems are used. Why a parachute mortar? Well, number one, this becomes necessary when saving on cost by using an old plastic bottle for the nose cone, and number two, I was interested in this deployment approach for another project I'm working on: a full-scale, K445-powered model of a TOW 2B anti-tank missile using the long "nose fuse" to contain and deploy a 70" chute on the 5-foot long blunt-ended model.

Construction:
Construction of Aquafina began with cutting up the wrapping paper tube to create an 18" body tube and six 1 1/2" tube fins cut on the bottom to a 22.5 degree angle. Tube fins measure 1 1/8" on the short side. Construction of the airframe follows that of Cheap Dumb Rocket and Auracle 54 on this website. 5-minute epoxy was used throughout. The bottom 2" was cut from the PET water bottle, and the resulting "nose cone" was permanently attached to the body assembly; since the PET bottle chosen is slightly wider than the cardboard tube,"shims" consisting of a dozen Q-tips dipped in wet epoxy were inserted between the tube and the plastic bottle around its entire circumference. To make complete a gas-tight seal, the gaps between the Q-tips were filled with bits of epoxy-dipped cotton. A launch lug of 3/16" ID was cut from a discarded ball point pen cap and epoxied to the body tube 2 1/2" above the tube fins in line with one of the spaces between the tube fins. The motor mount for the twin 24mm motors consists of two 5" lengths of 24mm tube stock, fitted with Estes motor hooks and blocks in the usual way, simply glued side-by-side. No centering rings are used; the cluster motor array is simply slathered with epoxy and slipped into the aft end of the body tube since the fit was pretty good. With all that surface area bearing the sheer loads, there was no need for centering rings. The substantial gaps left between the body tube and each side of the twin cluster were plugged with hunks of cotton soaked with epoxy--this insured proper ejection charge pressurization.

Finishing:
Painting was with aqua-colored spray paint.

Flight:
First flights were on a pair of D12-5 motors. Sims (at Cd=2.4) predicted an apogee of 400-500' AGL and max velocity of about 170 mph. Aquafina flew at least that high. D12-7's work equally well. Use of F21's should give at least 1000' per simulation. With all that drag, Aquafina pretty much just stops when the motors quit. Boosts were straight and quick--probably quite a bit higher and faster than the simulation indicated.

Recovery:
I attached a 24" length of 3/8" wide elastic shock cord to a 14" LOC chute at one end and anchored the other end with a gob of epoxy about 2" down from the mouth to the inner wall of the PET bottle. The "parachute mortar" consists of a 4" length of 29mm Estes tubing epoxied to the top of the bottle, however, I added it as an afterthought--on the first flights, I tried just stuffing the parachute part-way into the open mouth of the bottle, however it wouldn't deploy this way, even under the power of twin D12 ejection charges. From this, I learned that Aquafina is so light for its size, and so tail heavy, that even with no ejection, it tumbles down from apogee very slowly, in a flat spin, landing with no damage. I'd omit the recovery system entirely, but for a rocket this size, it would be poor form, and also a violation of NAR safety rules. And that's it...construction, including painting, took little more than an hour, with time out to watch the Chargers get creamed by Oakland. Final weight was 130 grams (about 4.5 oz.)-- not bad for a 2x24mm cluster design.

Summary:
Bottom line: Aquafina is a good cheap fun-fly rocket, low cost (need only to purchase the recovery chute.

PROs: Aquafina is was way too much fun to fly to use only for "research purposes". Cost of construction (for me): $0.00. It's based on a standard-sixed PET bottle, which are easy to come across. Good rocket for junior flyers and cheapskates. Good rocket for learning cluster flying with minimal investment in time or dollars.

CON: Well, it is a tad ugly, like most tube-fin designs. You may have to scrounge to find suitable sized body tubes and PET bottled of slightly larger tube diameter.