Design, Construct, Compete (DCC) Challenge!

Competition Rules



Each team must construct a device to launch a tennis ball through a suspended aperture and have it land in a horizontal hoop.  Each team will have 3 tries to launch a ball through the aperture and land in the target.

Teams and Registration

Date of the event is March 16, 2019.  First round competition will start at 2:30pm, but all teams must register their device on-site before 1:00pm.  The facilities will be open for practice and calibration for teams who have registered between 11am and 1:30pm.  All competitors must be present for the Competitors’ Meeting at 2:00pm. 

Teams must complete and submit a registration form and registration fee on or before March 1st.  Registration forms and fees will be accepted at Sisters High School during normal business hours.  Forms should be delivered to Mr Scheele in rm 222 at SHS, or may be left for him at the front office.  Forms may also be mailed to the address shown on the form itself.  Depending on the number of team entrants, late registration may be accepted at the discretion of the event organizers, but late registrants will not receive event t-shirts.

Teams may be comprised of one or more individuals of any age.  All members who contributed material or know-how to the device shall be identified on the entry form.  The team must notify the judges of any changes to the composition of the team between the time of registration and the competition itself.  No more than four t-shirts will be supplied to any one team.  Shirt sizes supplied will be those listed on the original registration form.

An individual team member may compete as part of one or more teams.  The same team may enter more than one device only if they complete a separate registration form for each device and if, in the opinion of the judges, the multiple entered devices are considered to represent substantially different design approaches.

Location and Dimensions

The competition will take place at the Sisters High School gymnasium before a live audience. 

The launch area will be designated by taped markings on the floor surface.  Teams and devices will be provided a clear area of approximately 3 m x 3 m during their turn at launch, with the front edge of this square defined as the launch line.  All personnel and equipment associated with the device must be entirely behind the launch line at the time of launch.

The target is a circle (“hula hoop”) with an inner diameter of .88 m.  The hula hoop target will be held horizontally (the plane of the circle will be parallel to the plane of the gym floor) at a height of 1.5 m off the floor. 

The “target distance” is defined as the distance between the midpoint of the launch line and the projection to the floor of the midpoint of the target. 

The minimum target distance is 5 m.  This will also be the target distance for the first round of competition.  The maximum target distance is 26 m.

Above the midpoint of the line defining the target distance, an aperture will be suspended vertically.  The aperture has inner dimensions of 2 m x 2 m.

The “aperture height” is defined as the distance from the midpoint of the line defining target distance to the midpoint of the aperture. 

The minimum aperture height is 2.75 m.  This will also be the aperture height for the first round of competition.  The maximum aperture height is 6.5 m.Between each round of competition, the judging staff will select a new target distance and aperture height.  Either of these dimensions may be independently adjusted to any value between their minimum and maximum ranges.  While both dimensions will start at their minimum settings for the first round, the judges are likely to explore a wide range of short/long and low/high setting combinations, necessitating that competitors adjust their devices over a range of elevation and velocity settings.In a successful launch, the projectile will pass through the aperture, then the hula hoop.  Most shots high of the aperture will be obstructed by drapes, and most low of the aperture will be obstructed by hanging streamers.  It is conceivable that some shots not passing through the aperture are able to avoid these obstructions and make it to the target.  Such shots will be judged unsuccessful. 

Projectiles which bounce off the rim of the target and then pass through the plane of the hula hoop will be considered successful; ones that bounce off the rim and out will be considered unsuccessful.  A net is suspended below the hula hoop to entrap the ball, making successful landings clearer to the audience, but under unusual circumstances, balls which have passed the plane of the hula hoop may not be entrapped in the net, or balls which were not successful wind up in the net.  All final judging of successful/unsuccessful launches will be made by judges at the event.

Device and Projectile

Each team’s entry shall include one apparatus for launching a projectile toward the target (a “device”).

Once the projectile is loaded into the device, the device shall mechanically accelerate the projectile from a state of complete rest through one or more stages of acceleration before the projectile is released.  After loading, no kinetic energy may be provided to the device by hand or by forces other than those applied by the device itself.

The device must release the projectile (must give up any direct mechanical contact with the ball) from behind the launch line, at a distance of no more than 3.0 m from the floor surface.

If a ball is errantly released from the device (falls off before the intended release, for instance), it will be counted as one of the team’s three attempts only if it crosses the plane of the launch line.  Balls that are shot vertically, backward, or with insufficient velocity to cross the plane of the launch line will not be counted against the team.

Devices may use pneumatics, electric motors, springs, torsion arms, tension cables, or other means of converting potential energy to kinetic energy according to the creativity and design of the team.  However, no device shall use combustion of any sort as a means of power.  Liquid and solid fuels are specifically disallowed.

The device shall not rely on “wall socket” power.  If a device is operated with electrical power, this must be supplied by the team using batteries or a non-combustion powered charger/generator.

Teams must be capable of transporting, setting up, aligning and shooting their device in the times allotted.  There is no path from the outside of SHS into the gym through entirely wide-bay doors.  Particularly large devices may have to be partially disassembled to have access into the facility.  Each team is responsible to confirm that their device is able to fit through publicly-accessible doors.  Event organizers will not be able to disassemble door frames on the day of the event to accommodate large devices.

The “three-minutes to set up and shoot” requirement (Rule 29) of the competition and the “two-minutes to clear the launch area” requirement (Rule 30) are both intended to create additional design constraints for the design of the device.  Teams are encouraged to give adequate consideration to issues of transportation and alignment in the design of their devices and any accoutrements which they require during set-up and use.

Any device which, in the opinion of the judges, presents a hazard to spectators or entrants, or which presents a possibility of damaging the surface of the gymnasium floor, ceiling, walls, or fixtures will be disallowed from competition.  Entrants are encouraged to contact our judges in advance if they have any questions about the legitimacy of their device or approach to this contest.

The projectile to be launched is a standard, commercially available tennis ball.  Teams may provide their own tennis balls if they choose.  If requested, on the day of the competition, the organizers will make up to three balls available to each team.  Balls provided to teams by the organizers will be new, pressurized and fully covered in felt. 

Teams may not modify the tennis balls used in this competition, other than by removing some or all of the fibrous felt which normally covers the surface of the sphere, or by puncturing – but not otherwise modifying – the rubber pressure chamber.  Specifically, changes which substantially add or subtract to the mass of the tennis ball projectiles are prohibited.  All tennis ball projectiles used in this competition shall have a mass between 50 and 60 g.


The order of competition between teams will be chosen by random before the start of the first round.  All teams which advance to subsequent rounds will continue to compete in the same order with respect to all other teams still competing.

Only one team will be allowed into the launch area at a time.  Other teams will await their turns outside the launch area, and will be expected to courteously allow other teams their best opportunity to stage themselves outside the launch area as their turn approaches.

When it is their turn to compete during each round, each team will be given a total of three minutes to move their device into the launching area and to launch up to three balls (see Rule 19 for a definition of a launch for purpose of the competition) in an effort to land at least one ball in the target.  Balls may only be launched one at a time.

Each team will be given two minutes after their three-minute round is complete to clear the launching area in advance of the next team’s effort. 

The first round of competition will consist of up to three attempts by each team to successfully land at least one ball in the target. 

Teams who successfully land at least one ball in the target will advance to the second round.  Teams who successfully land a ball in the second and each subsequent round will continue to advance to subsequent rounds after that.

As soon as a team successfully lands one ball in the target, that round will be considered a success for that team.  That team has no obligation to continue on with a second or third attempt during that round (unless it is a Sudden-Death Measure-Off Round, see below).

Teams who are unable to land a successful shot during their allotted three minutes – either because all of their shots missed the target, or because they were unable to complete all of their shots during the three minutes allotted – will be eliminated from the competition (unless they are eligible to compete in a Sudden-Death Measure-Off Round).

Teams which are unable to completely clear the launch area in the two minutes following their turn will be eliminated from the competition. 

At the start of the first round, the midpoint of the target will be at a distance of 5 m from the midpoint of the launch line, and the center of the aperture will be at a height of 2.75 m off the floor. 

Between each round, the target and launch line may be symmetrically moved such that the distance between them is anywhere between the maximum and minimum limits of 5 m and 26 m respectively.  The positioning of both the launch line and the target will be adjusted, such that the location of the aperture remains at the midpoint of the target distance.  Between rounds, the aperture may also be moved such that the height of its midpoint off the floor is anywhere between the maximum and minimum limits of 6.5 m and 2.75 m respectively.  Judges will determine the target distance and aperture height, and announce to all teams the new dimensions before each round begins.  Target distance and aperture height will be the same for all teams each round.

Competition will continue until only one team is able to successfully land at least one projectile in the target at a given distance in a round.  If only one team is able to successfully land a projectile in the target at a given distance, this team will be declared the winner of the competition.

If competition ends without a Sudden-Death Measure-Off Round, all teams who successfully landed a ball in the target in the last round previous to the winning round will be considered runners-up, and will equally split any runner-up awards.

In the event that multiple teams advance to a round where none of these teams are able to successfully land a projectile in the target, each of these teams will be given a second chance at the same distance/aperture height.  If after this second chance, more than one of the teams has a successful throw, competition will resume as before, with subsequent rounds at different, more difficult distance/aperture height combinations until only one team has success at that combination.  If after the second chance round, all of the remaining teams again miss the target, these remaining teams will then compete in a Sudden-Death Measure-Off Round (see below) at that distance.

Sudden-Death Measure-Off Round

In a Sudden-Death Measure-Off Round, the hula hoop target will be removed, an aperture height will be announced by the judges, and a new target will be marked by a spot on the floor of the gym designated by a taped cross-hatch.  This marker will be placed directly below the center of the hula hoop at the distance where it had been located during the round immediately preceding the Sudden-Death Measure-Off Round.

The order of competition for the Sudden-Death Measure-Off Round will be the same as for all prior rounds.

Teams competing in a Sudden-Death Measure-Off Round will each have 3 minutes to launch three balls at the target spot.  Judges will place a marker at the location where each of the three balls strikes the surface of the floor.  The location of each ball’s landing will be marked solely at the discretion of the competition judges.

Teams who are unable to launch three balls in their allotted time during a Sudden-Death Measure-Off Round will be eliminated. 

After their three launches are complete, judges will measure the distance between the target mark and the point where each of the three balls struck the floor.  Balls which do not pass through the aperture will be scored as having a distance of 8 m from the target.  The sum of these three distances will represent that team’s score for the Sudden-Death Measure-Off Round.  (For instance, if a first launch does not cleanly pass through the aperture, a second lands at a distance of 1.3 m from the mark, and a third a distance of 0.6 m, that team’s score would be a total of 9.9 m.)

The team with the lowest score in the Sudden-Death Measure-Off Round will be declared the winner of the competition.

If competition ends with a Sudden-Death Measure-Off Round, the runner-up team is the team with the second-lowest score in the Sudden-Death Measure-Off Round.

Prizes and Awards

The nature, size and scope of any contest prizes will be announced separately by the organizers. 

Depending on the number and characteristics of teams who enter the contest, the organizers reserve the right to divide the competition into more than one category (i.e. student teams, corporate teams, middle-school teams, etc.) and adjust prizes accordingly.

The final awarding of prizes will be announced immediately following the competition.

Any awards will be given to the team overall.  Contest organizers will have no input or responsibility regarding how a team chooses to allocate amongst itself any prizes it may earn through this event.Judging

All rules shall be interpreted and enforced by a panel of three judges selected by the organizers. 

In cases where these published rules may not fully address an issue which affects the competition, the judges are empowered to add or modify rules at any point in time up to and throughout the actual competition to clarify any ambiguities.  Any such changes will be made in a spirit of safety and fair competition, and will be communicated to all participants in a timely manner.

Judges reserve the right to eliminate any team or device which, in their opinion, could present a safety concern for participants or spectators, or which has the possibility of creating damage to the competition facilities.

trial 2
Figure 1:    Schematic view of DCC Challenge layout, showing minimum and maximum dimensions for the target distance (left/right) and the aperture height (up/down).  The launch line and target will both be symmetrically moved, such that the centerline of the gym floor is always at the midpoint of the launch distance.  The square (2 x 2 m) aperture will be raised or lowered above the centerline.  The target distance and aperture height may be independently varied between these min/max ranges, such that a great variety of trajectory arcs may be required for a successful round.