Unfortunately this event has been Cancelled.

We hope to be able to reschedule this event in the future.



19, 2017
Check-in 9am
Compete 10am

Teams must register to compete.  Advance registration is $10 and can be done on this website or in person at M4Reactor BEFORE August 19. Registration at the door will be $15.

NOTE: The rules presented here may be updated before the competition.  Please check them regularly.  If you have any questions, please let us know at info@m4reactor.org.


The goal of this competition is to encourage learning in the fields of engineering by designing and building a seige weapon.

Each entrant must design, build and present a siege  that will accurately propel a baseball (standard professional).  The catapult must be based on a historical siege weapon like a catapult, onager, trebuchet, mangonel, balista or simlar device.  The method of propulsion must be either torsion via rope or by counterweights.

General Rules

  • Individuals and teams of all ages are encouraged to enter!
  • Registrants must pay a registration fee of $10 (early bird) or $15 at the door.
  • The siege engine may be composed of any safe material but must represent a historical siege engine.  This means no air cannons or other modern technology.
  • The judges will have final say on if a siege engine may compete based on it's historical representation.
  • The siege engine must fit within a 3’ x 3’ x 8’ box. The base must be no larger than 3’ x 3’ and the 8’ dimension extends vertically upward. When firing, parts of the siege weapon may extend beyond this volume, but may not touch the ground outside the launch area.
  • The catapult should be of sufficient mass to ensure that it remains behind the launch line after the projectile has been launched.
  • Siege engines must be safe and controllable. Participants are responsible for the safety of the operation of their design. Prior to competition, judges will disqualify any catapult that appears unsafe.
  • The projectile will be a standard professional baseball.  We will provide the baseball for launching.

Competition Format

  • There will be 2 firing rounds.  You may choose to participate in either or both.
  • The first round is distance.  The second round will be who can hit closest to a flag placed 15 yards from the launch point.
  • In turn, each entrant will set up his or her siege engine on the launch pad, which consists of a 3’ x 3’ solid surface.
  • You will get 3 opportunities to fire the projectiles.  You will have 8 minutes to initially setup and to launch the first projectile and 5 minutes for each successive launch.
  • A launch round shall be considered such when the projectile leaves 3' x 3' base OR when the machine has started is unmanned motions OR when the timed launch window is up. If you have additional launches, your next launch window timing will start.
  • The position of the projectile's first hit will be where the distance is measured from (not the final resting point).
  • The siege weapon will receive a score of zero  if the weapon crosses or moves into the launch line.
  • Decisions and interpretations of the rules by the judges are final.
  • The best measurement per firing round (distance or closest) will count as your final score.

Historical Competition

  • After the firing rounds, we will have all machines judged based on their historical accuracy.
  • Judges will score entries based on Design, Method of Construction and Appearance (equally weighted).

Awards Presentation

After all 3 rounds, the judges will confer for 20 minutes to recheck all documentation.  We will then present the awards.  Awards will be given for the Top 3 competitors in Distance, Top 3 competitors in Accuracy and the Top competitor in Historical Accuracy.