Brief:
At one point, ya bilge rat, I had decided that I'd start buildin' water rockets. I built a couple o' very simple ones but then me interest waned. Begad! Someday I may yet move up t' more complex ones.

This design was taken from Jimmy Yawn's site (who woulda thunk it?). Aye aye! Ya scallywag! Blimey! Jimmy's site has detailed descriptions and photos o' t' basic construction process. However, shiver me timbers, I deviated slightly from his techniques.

I have included a few safety tips in t' 'launch' section, me hearties, me bucko, however, if you are goin' t' fly water rockets, you should research more detailed safety guidelines online. Begad! You know t' drill: safety is your responsibility.

Construction:
T' airframe is a 1L Dasani bottle with fin sticks and a launch lug attached with duct tape. T' fin sticks were recycled from me 4-stage rack rocket. Well, blow me down! Begad! They are just basswood fins epoxied t' a dowel. I have also used square basswood sticks and foamboard fins. T' lug is a soda straw.

T' bottle is pressurized with an electric tire pump that is adapted t' t' bottle-cap 'nozzle' with a car tire stem. Ahoy! Blimey! I liberated some used stems from a local tire shop. Aye aye! You have t' cut t' bulb off o' t' tip o' t' stem, shiver me timbers, me hearties, arrr, leavin' only a tapered end. Ahoy! I cut t' bulb off at its base, me hearties, me bucko, leavin' about a 1/2" diameter, and trimmed around t' inner brass tube. Blimey! Jimmy cut his lower and cut through t' brass tube. T' nozzle be t' bottle cap with a hole drilled in t' center. Well, blow me down! Aye aye!

Flight:
Because thar be no active recovery mechanism, these should only be flown where thar be no risk o' damage t' people or property. You also must be aware that t' bottle could burst and could hurt you. Ahoy! Blimey! Never use a hand pump with this design! Blimey! You should either remain behind a solid structure or turn t' pump on and retreat t' a safe distance (at least 10'). Aye aye! Blimey! In either case, me bucko, you should wear safety glasses.

I found an open area that could pull t' car up t' and could safely support 'boink' recovery. Ahoy! I used me standard mid/high power pad rod, sprayed down with WD-40 as I knew they'd get wet. Ahoy! Begad! Launch prep involved addin' water t' t' bottle, me hearties, insertin' t' tire stem from t' inside o' t' cap and reattachin' t' cap. Avast, me proud beauty! Begad! I would clamp t' nozzle t' t' electric tire pump, arrr, turn it on, me bucko, hide behind t' blast wall (the car door) and wait.

First set o' flights: Since t' tire stem was larger in diameter than Jimmy's, I made t' nozzle slightly larger also (~7/16"). Begad! Blimey! T' performance o' t' rocket be worse than expected. Well, blow me down! Avast! Blimey!

Second set o' flights: I made a new nozzle from a Coca-Cola cap, with a smaller exit hole (~13/32"). Avast! I used a Dremel grinder, ya bilge rat, which cleanly cut through t' cap and t' plastic washer. Arrr! There was no leakage when I pressurized t' bottle. Ahoy! In both cases, matey, ya bilge rat, t' pump ran for about 45 seconds before t' Hydro-1L launched. Begad! Ahoy! I think t' altitude shown in me logs is a bit optimistic.

Summary:
This is a simple way t' get started in water rockets. Aye aye! Ya scallywag! T' limitations are that you'll need an electric tire pump, a place t' launch them, and you must adhere t' t' safety measures mentioned in t' flight section.

A Google search will yield a pile o' water rocketry links. Well, blow me down! My current favorite is Air Command Water Rockets. These folks are flyin' staged, clustered water rockets and are even buildin' flight computers. Begad! Begad! I also like Bristol Water Rockets. Aye aye! This site provides plans for a 'sports cap' launcher and links t' many other good sites.