The WRA2 Class D Water Rocket world record competition enables teams and individuals the opportunity to compete against each other for the overall altitude record for water rockets constructed using soft drink bottles and without the high cost of exotic materials.

  1. Unreinforced Bottle General Design Parameters

    1. Rocket must use water as its primary reaction mass.
    2. 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).
    3. Water Rocket must use compressed ambient atmospheric air at no more than 100 PSI (6.9 Bar) 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).
    4. Launch pressure must be measured with a minimum 3% accuracy Gauge.
    5. Rocket must be completely scratch-built using materials which are not manufactured as model rocket parts (with the exception of the Camera and Altimeter). Raiding hobby shops for nosecones, or fins, or any other pre-manufactured items is prohibited. (manufactured items that are not designed for rocketry such as wind up toys are allowed)
    6. Rocket must carry onboard a mass produced altimeter to document the maximum altitude of the flight. Ground based and/or timing based altitude measurements are unacceptable.
    7. Launch and launch pressure of each flight must be recorded by ground-based video.
    8. Entire flight including apogee must be photographed by an onboard video camera. If using a peak altimeter then the ground video will also show the display of the altimeter as the rocket is recovered following each flight.
    9. Record altitude is calculated as the average of the two highest flights the rocket achieves within a 2-hour period (note: If using a peak altitude altimeter the average will be for 3 flights in 3 hours). Results must be repeatable!
      10. (This criteria was inspired by high profile competitions such as the Ansari X-Prize.)
    10. 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.). Items which are damaged in any record attempt must be repaired and rockets are disallowed from competing.
    11. Rocket must reach apogee as a single unit but may seperate at apogee (if the rocket seperates, all parts must have a recovery system to slow the descent to meet the maximun descent rate)

  2. Bottled Air Rules

    1. Only bottled atmospheric air is allowed. No exotic gasses, cryogenics or combustibles.
    2. Tanks must be certified. (copies of tank certifications will be provided and filling station receipt).
    3. 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.
    4. To prevent "stomp rockets" the rocket must remain pressurized to full launch pressure (100PSI or 6.9 bar) for a period of no less then ten (10) minutes. (The ground view camera will show both the tank and rocket on the launcher during this 10 minute period).
    5. 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).

  3. Safety Rules

    1. All WRA2 Water Rocket Safety Rules must be followed.
    2. 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.
    3. 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.

  4. Pressure Vessel Rules

    1. Pressure vessel and fuselage of rocket must be constructed from a single unmodified soft drink bottle which cannot exceed 2 liters (labeled capacity) volume. (commercially produced stretched or modified bottles such as the U14 stretched water rocket bottle by Anti Gravity Research are not allowed)..
    2. Beverage container may not be modified in any way.
    3. Beverage container will not exceed a labeled volume of 2 liters (a photograph of the bottle with the label visible will be required to be eligible).
    4. 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.
    5. A photograph of the bottle with it's original label visible will be required (this will be proof that a beverage container was used).

  5. Reaction Mass & Launcher Rules

    1. 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.
    2. Projectiles from Air Cannons are not acceptable.
    3. Reaction Mass must be primarily ordinary tap water.
    4. Thrust must come from expelling reaction mass, not from air discharge.
    5. Water reaction mass must fill a minimum of 20% of the volume of the Pressure vessel (400ml).

  6. Filing a Record Claim

      All record claims must be filed to the WRA2 Contest Submissions for public review.
      Items required:

      1. Unedited onboard videos for both flights (Videos may be uploaded to Youtube).
      2. Mass of rocket (a photo of the rocket on scale with reading visible is also acceptable).
      3. Ground videos for both flights (Videos may be uploaded to Youtube).
      4. Detailed still photos of the bottle(s) used to construct the rocket (with original label visible).
      5. Detailed still photos of the finished rocket.
      6. Make and model of pressure gauge.
      7. Photo showing launch pressure as displayed on gauge for each flight
      8. Time and date for each flight.
      9. If using bottled air: copies of the tank and operator certifications.

      Optional Items:

      1. Detailed still photos or videos of the rocket being constructed (Videos may be uploaded to Youtube).
      2. Design drawings.
      3. Simulator data.
      4. Atmospheric data at time of launch (temperature, barometric pressure, and relative humidity).
      5. Photo of Pressure gauge.

      Maximum file size 45MB per file.

  7. Questions & Answers

    1. 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.