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JPL Annual Invention Challenge - 2001 Rules
The JPL Annual Invention Challenge is ready for its fourth year. The title for this year's contest is the Water Balloon Launch Contest. The objective and rules are listed below. Questions related to this contest should be directed to: Paul MacNeal at: work phone (818)354-7824, FAX (818)393-1324, MS 301-320, located in Building 301-325Q, or e-mail to

Objective: Create a device that launches an official water balloon in a vertical direction. The contest winner will be the person whose device launches an official water balloon the highest above the ground and has the balloon contact the ground intact within a specified circular target.

  1. The contest is open to all JPL employees, contractors, and immediate family members. This year, it is also open to teams of students from local high schools. Family members, friends, and classmates are welcome to watch the contest, but must be cleared through the security office prior to arrival. Applications for JPL employees, contractors, and immediate family members entering the contest must be filled out and submitted prior to midnight November 30, 2001. Schools must submit their entry forms prior to November 9, 2001 with a list of participants on or before November 30, 2001. Ken Berry at (818)393-5386 will be the point of contact for all school entries.
  2. The contest date and time is Friday, December 7, 2001 between 12:00 and 1:00PM. The contest area is at JPL, north of the fountain area in front of the Building 180 steps.
  3. Each contestant will be given two chances to operate their launching device. No practice runs are permitted. Given two chances, only the highest water balloon will be used for judging. In the event of a tie between two or more contestants, their second-highest balloon launch (if a contestant made two qualified launches) will be compared to determine the winner. In this case, a disqualified balloon launch will have a height of zero. If a tie still exists after making comparisons as previously described, then the contestants that are tied will each be awarded equal trophies.
  4. Balloon The official water balloon is provided on the day of the contest. Each contestant will choose their two water balloons prior to the start of the contest. The order of selection will be based on the contestant's entry form number that is assigned on a first-come first-served basis. Every attempt will be made to provide a consistent quality of filled water balloons. Each water balloon will be subjected to pre-screening by performing a drop test (approximately 180cm onto a smooth hard surface). Any balloon that leaks or bursts as a result of this "drop" test will be discarded. The balloons are standard size water balloons made of pure latex. Each water balloon has a mass of 300 grams with a maximum deviation of +/- 10 grams. No alterations to the water balloon of any kind are permitted. The overall size of a filled water balloon suspended by the knot is a "tear-drop" shape approximately 75 mm in diameter and 120 mm tall. Practice balloons (empty) can be purchased for experimentation and calibration. Eight balloons will cost $1.00 and can be purchased from the contest organizer, Paul MacNeal (see above for phone number and location at JPL).
  5. The launch device must have the following characteristics:
    • The launch device is an automated mechanical system that propels the water balloon in a vertical direction and does not utilize human contact in any way to propel the water balloon.
    • The launch device must have a single operation to initiate the launch sequence. Examples of this include cutting a string, pulling a pin, pushing a button, etc. No human contact with the water balloon is allowed once the water balloon is placed inside the device.
    • The launch device must be smaller than an imaginary box that is 2 meters high, 3 meters wide and 3 meters long. The launch device must be smaller than this "box" before, during, and after the launch. The launch device is defined as anything that is not the water balloon.
    • The launch device will contain an energy method to propel the water balloon. A powered extension cord will be available. The choice of energy system is optional but has a few restrictions. The energy method must be safe to the contestant and all observers. Unsafe methods of energy, as determined by the contest organizer, will not be allowed to compete. Some examples of disallowed energy methods include explosive reactions, chemical conversions with toxic by-products, and unsafe high-pressure air systems. Questions regarding the acceptability of a candidate energy source can be submitted to the contest organizer for a ruling. Controversial energy sources must be approved by the contest organizer prior to November 30, 2001.
    • The launch device must place the initial vertical trajectory of the water balloon within 3 cm of the target centerline at a height of 2 meters above the ground (see Section 7 for an explanation of why this is important).
    • The launch device must be adaptable to non-level surfaces (see Section 6).
    • The launch device must be set-up, aligned, operated (once or twice), and removed from the target area in less than five minutes. A second launch attempt may be disallowed if too much time has been taken during the set-up and first launch attempt.
  6. The launch site and target area is located in front of the Building 180 steps at JPL. The surface is hard concrete and is not level. The slope is approximately 2 degrees. Absolutely no modifications to the ground are permitted. To provide for more entries, two identical target zones will be used, with the centerline of the target circles being separated by 5 meters. The target circle that the water balloon must land within is 7 meters in diameter. A water balloon landing on the 7-meter diameter chalk line will be permitted. The water balloon must make initial contact with the ground intact. A water balloon that bursts or leaks prior to contacting the ground will be disqualified.
  7. Measurement of the maximum height of the launched water balloon will be calculated based on time aloft. Measurement of time aloft is considered reasonable rather than actually measuring the maximum height of the water balloon because all the water balloons are nearly identical and no modifications to the water balloon are permissible. A simple formula will be used to convert time into height. Timing will begin when the balloon crosses a point that is 2 meters above the ground on the way up. Timing will stop when the balloon first contacts either the ground or the device. To measure the start time, an electric eye will be set-up so that the water balloon will break the beam of light and instantaneously start the clock. The timing judge will stop the clock by hand. Two additional timing officials will independently measure time aloft using hand-held stopwatches. In the event that the electric eye (or timing judge) malfunctions, the two timing officials will average their respective aloft times to arrive at the official time. Times used for calculating height will be rounded off to the nearest 0.05 seconds.
  8. Trophies will be divided into two categories: JPL employees/family entries and school entries. Trophies for highest water balloon will be given for first, second, and third place for each category. Certificates will be issued for the lightest, heaviest, smallest, largest, most unusual, most artistic, and most creative designs.
  9. The formula used for calculating the height (in meters) has been provided by Dr. Terry Scharton and is:

    H = 4.907[t/2 - .2037905/t]2 + 2.0

    Where t is measured in seconds, and acceleration due to gravity is assumed to be 9.814 m/sec2.

    A sample of times versus heights is given below:
Time (seconds) Height (meters)
1.30 2.00
1.30 3.19
1.80 5.04
2.80 10.64
4.00 20.64
5.00 31.68
6.00 45.17

Download Entry Form Here. (6 K .pdf file)

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