The physics of air-water rockets and fuel rockets are different but also similar. In a conventional fuel rocket, the propellant is pushed out through the nozzle by mixing explosive chemicals like liquid oxygen and hydrocarbons together as the energy source. In an air-water rocket, the propellant is water, and the energy source is compressed air.
How to build
1.25Litre PET Soda bottles are used as the pressure vessel of the rocket. Soda bottles have a typical pressure capacity of 14 Bar or 1400kpa (+200psi) and can be recycled. Our rocket launcher uses 4.5 Bar for +90 metres of lift into the air.
The Rocket Launcher uses a RC controlled 12V Air-Compress able to pressurise 4 rockets relatively quickly to 4.5 Bar.
Check valves ensure pressure is maintained in each rocket when others are lunched.
Air Tap Ball Valves are used to manually close off air to other stations to allow the pressurisation of launch of less than 4 rockets.
Compatible PET Soda Bottle Cap is drilled out to 20mm using a 20mm tapered drill.
Bicycle tyer inner tube used and cut into 20mm long pieces to make a pressure tight gasket.
A 19mm irrigation barb to snap-on hose connector adaptor is used as the latching system connecting to the Rocket Launcher.
A 12mm Brass Garden Hose snap-fit connector is used as the main Rocket Launcher release mechanism.
Also a 8mm x 260mm brass tube is soldered to the inside providing an air bypasses, through the water inside the rocket and also provides assistance in guiding the rocket straight when launched.
Stainless flexible cable is used and clamped to the snap-fit ring and then looped underneath to connect the servo via Teflon sleeves to ensure the cable moves freely.
When the servo is operated the snap-fit ring is pulled down to release the rocket under pressure.
