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Design Challenge 2013: Trebuchet Competition

For more information, visit http://bcengineers.weebly.com/

Objective:

Participants will build a trebuchet to throw a hacky sack as far and accurate as possible, given three throws.

Materials:

Any material that is not of a hazardous nature may be used. Judges can deem any entry unsafe if they see any safety hazard or anything that may seem a safety hazard.

Rules

General

1. Teams must design, build and operate their own trebuchet device.
2. The device must be solely powered by the energy available from the dropping counterweight: No motors, springs, bands or other object may be used to increase the available energy.
3. Use of a sling is required in the competition. Two types of slings are allowed in the competition:
   1. Staff sling attached to the end of the throwing arm - one end of the sling is fixed to the end of the arm, and other is looped around a release point.
   2. Single string sling attached to the individual projectile and the other end looped around the release point.
4. The design must have 2 locking mechanisms. One lock is for triggering the device, and the other is for safety. The triggering mechanism must be designed so the participant can trigger the device from at least 5 feet away. The safety lock is for resetting the device and setting the projectile.
5. The design must fit in a box with the following dimensions: Base is 1x1 meter square with a height of 1.2 meters. The height is with rotating arm loaded with counterweight attached and setting vertically, with the throwing side straight up in the air.

Counterweight:

1. The counterweight mass must not be greater than 5 kg.
2. The coutnerweight must be detachable for mass measurement. All materials used to attach the counterweight must be included in the 5 kg.

Projectile:

1. The projectile will be a hacky sack.
2. The projectile will weigh about 40-50 grams.
3. The projectile will come in one of two ways. This will depend on the sling type used.
4. The projectile must begin in contact with a horizontal surface no higher than 3 cm above the launch pad surface. The launch pad itself may serve as this horizontal surface.
5. The projectile must not drop in height during the launch motion.

Rotating Arm:

1. The rotating arm must include its own pivot point. External pivot points are prohibited. There must only be one pivot point.
2. With the counterweight and sling removed, the throwing end of the rotating arm must be heavier than the counterweight end of the rotating arm.
3. The rotating arm must not flex in such a way as to store additional energy for the task when placed in the “ready-to-launch” position.

Safety:

1. Participants must operate their device in a safe manner. The device may not be activated while team members, judges or spectators are behind the device or in the competition area. Teams using UNSAFE PROCEDURES may have trials disqualified at the discretion of the judges
2. The device must be sturdy enough as to not pose a danger to students, officials or spectators during operation, as determined by the judges.
3. The device must remain within the launch area during operation. Participants must let the device come to rest without assistance. EXCEPTION – The throwing arm may extend outside the launch area when the device is in “ready-to-launch” position.

Inspection and Operation:

1. The device will be inspected for safety and for build spec compliance at time of registration of device on the day of competition.
2. The device must be ready for competition when called or forfeit that trial.
3. The participant responsible for triggering the device will indicate to the judges when device is in the “ready-to-launch” position.
4. Participants must wait until the judge gives the “start” order. If device moves before this, a “false start” will be declared and that trial will be disqualified.

Scoring:

1. Scoring will be best of three throws.Scoring will be best of three throws.
2. Scoring is based on distance and accuracy.
3. There will be a score line that is set from the center of the launch area and extending straight out from there.
4. Points are awarded as follows:
   1. The projectile is measured from the scoring line.
   2. For every foot the projectile travels down the line, a point is given.
   3. For every foot measured perpendicular from the score line a projectile lays, a point is subtracted.
5. There will be four divisions competing in the competition. The participant with the most points at the end will be declared the winner.
   1. Junior High
   2. High School
   3. College
   4. Open/Professionals
6. There may be other categories that may be judged and winners delcared; such as aesthetics and the best engineering design.