Water Rocket Single Stage General World Record Design Parameters
- Rocket mass cannot exceed 1,500 grams. This is the total dry weight of all flying components in a flight ready condition including the pressure vessel, fins, nosecone, payload bay, camera, altimeter, flight computer, deployment system, batteries, and nozzle (no reaction mass).
- Rocket must use compressed ambient atmospheric air as its energy. Other gasses have much higher compression ratios and there needs to be a baseline so the record is fair to all. (see section II for special rules regarding bottled air).
- Pressure vessel and all external parts of the rocket must be constructed from lightweight nonmetallic materials.
- Rocket must be completely scratch-built using materials which are not manufactured for model rocketry. (with the exception of the Camera and Altimeter) Raiding hobby shops for nosecones, or fins, or any other pre-manufactured items is prohibited.
- Rocket must carry onboard a mass produced recording ("Logging") altimeter to document the entire flight on a time vs. altitude graph to nonvolatile logging
memory or telemetry to relay the altitude information to a remote logging receiver. Ground based and/or timing based altitude measurements are unacceptable.
So-called "Peak Altitude" altimeters are unacceptable as they are subject to false peak readings.
- Launch of each flight must be recorded by ground-based video (if using bottled air is used than the 10 minute max pressure hold must be shown).
- Entire flight from launch to touchdown including apogee must be photographed by an onboard video camera.
- Record altitude is calculated as the average of the two highest flights the rocket achieves within a 2-hour period. Results must be repeatable! (This criteria was inspired by high profile competitions such as the Ansari X-Prize.)
- The same rocket must be used for all averaged flights. The only portions of the rocket which can be replaced are expendable or consumable items. (batteries, tape, deployment chemicals, water, etc.) The same rocket must be used for all attempts. Items which are damaged in any record attempt must be repaired and rockets are disallowed from competing.
- Rocket must reach apogee as a single unit but may seperate at apogee (if the rocket separates, all parts must have a recovery system to slow the descent to meet the maximun descent rate)
Bottled Air Rules
- Only bottled atmospheric air is allowed. No exotic gasses, cryogenics or combustibles.
- Tanks must be certified. (copies of tank certifications will be provided and filling station receipt).
- All local laws must be complied with for handling pressurized tanks as well as any certifications that the operator may need will also be provided upon a record submission.
- To prevent "stomp rockets" competitors using bottled air must leave the rocket at full launch pressure for a period of no less then ten (10) minutes prior to launching. (The ground view camera will show both the tank and rocket on the launcher during this 10 minute period).
- Bottled air pressure source must be located at the minimum safe distance of 50 Feet (15 meters) from the launcher (this allows the bottle air pressure source to be safely controlled in the event of an emergency).
- All WRA2 Water Rocket Safety Rules must be followed.
- All launched parts of rocket which travel over 6 meters (20 feet) in altitude must have a recovery system which limits their descent rate at time of touchdown at ground level to a maximum velocity of 10 meters/second (33 feet per second) This includes all pieces which separate or are shed off in flight. Fast falling rockets, boosters, debris, or rocket parts can be very dangerous. Recovery system malfunctions for any part will disallow any record flights.
- Metal components including but not exclusive to items such as screws, nuts, bolts, rivets, pipe, sheet metal, steel, copper, and alumminum shall not be attached to any pressurized portions of the rocket.
Pressure Vessel Rules
- Pressure vessel is defined as the portion of the rocket containing the pressure (tank, end caps, and nozzle).
- Pressure vessel must be fabricated by the rocket builder.
- Pressure vessel cannot be constructed using any portion of an existing high pressure enclosure (Paintball tanks, CO2 tanks, SCUBA tanks, propane tanks, etc. are prohibited).
- Pressure vessel and all external parts of the rocket may not be fabricated from metal. (see the WRA2 Water Rocket Safety Rules). Prohibited items include but not exclusive to are items such as screws, nuts, bolts, rivets, pipe, sheet metal, steel, copper, and alumminum.
Reaction Mass & Launcher Rules
- Reaction mass must be primarily ordinary tap water.
- Thrust must come from expelling reaction mass (water), not from air discharge.
- Water reaction mass must fill a minimum of 20% of the volume of the pressure vessel. Token amounts of water added in an attempt to qualify an air cannon projectile as a water rocket are not allowed.
- Rocket must be launched from a stationary position on a fixed launcher. (Slingshots, trebuchets, catapults, cannons, and all other forms of launcher boost assist are forbidden). Launch tubes are allowed as long as the internal pressure of the rocket is the only supply of energy.
Filing a Record Claim
- Onboard video for both flights.
- Ground videos for both flights
- Raw altimeter data for both flights
- Time and date for each flight.
- If using bottled air: copies of the tank and operator certifications.
- Detailed still photos of the rocket being constructed.
- Design drawings.
- Simulator data.
All record claims must be filed to the WRA2 Contest Submissions for public review.
Maximum file size 45MB per file.
Questions & Answers
- If you have any questions about the rules or if your rocket is eligible for world record competition, please post them in the WRA2 Competition Q & A forum for a prompt answer. Remember that if you are in doubt, ask before you build.