Projectile Launcher


To build a device that will move forward and launch a projectile (pencil).

Permitted Materials
  1. The mechanisms which move the launcher and propel the projectile must consist of elastic material such as springs, rubber bands, bungee cord, etc.
  2. Parts may be used from commercial objects (toys, models, etc.) but the frame holding the device together must be constructed, not purchased whole. There are no limitations on the types of frame materials used in the construction of the device.
Other Constraints
  1. No energy sources, other than the elastic material, may be used for propulsion or releasing the projectile.
  2. The device must be a single moving object and fit completely in a box 30 cm. X 30 cm. X 30 cm..
  3. The device may not make use of any type of remote control including strings or lines that protrude out of the launch zone. Lines may trail behind the device as long as they are moving. The lines must not be attached to a stationary weight.
Testing Procedure
  1. A testing area will be marked on a hard surface floor. One of the team members will release the launcher from behind a starting line and can no longer touch the launcher or any strings attached to it after it crosses the line. It must travel two feet and then enter a launch zone which is two feet wide and four feet long. The projectile must be launched from somewhere within the launch zone and be directed toward a horizontal (floor level) target point centered six feet beyond the end of the launch zone.
  2. The projectile will be an ordinary unsharpened wooden pencil (7.5 inch) launched eraser end first. The pencils will be furnished by the judges.
  3. Each contestant will be given three attempts. The best score (shortest distance from the center of the target) of the three will be used as the final score. The three attempts will be scheduled consecutively; however, contestants may opt to delay the third attempt to make minor repairs or adjustments.
  4. In the event of a tie, the second best of the three attempts will be the tie breaker. 
  5. Practice runs in the testing area, prior to the actual competition, will not be allowed.

College of Saint Benedict
Saint John’s University

Jim Crumley
Chair, Physics Department
SJU PEngl 107
Physics Department