Air Trajectory

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This article is about the event Air Trajectory. For the event Trajectory, see Trajectory.

Air Trajectory is a Division B and Division C event being held in the 2024 season. It debuted in 2015 after being a trial event at the 2014 National Tournament and was also ran in 2016.

The objective of the event is for teams to design, construct, and calibrate a device capable of launching a projectile onto a target. The energy for the launch must solely come from the gravitational potential energy of a falling mass. Teams are allowed up to 10 minutes for the competition and may comprise up to two members.

Event parameters stipulate that teams must collect and record performance and calibration data for their launch device prior to the competition. Each team is required to impound one launch device, a design log, and any projectiles they will use. The devices must be portable by team members without outside assistance, meet certain size constraints, and must use no external energy sources.

For scoring, teams are required to submit a Design Log, containing information on materials used, labeled diagrams, data tables or graphs, and example calculations for calibrating the device. Eye Protection B is required and participants must be able t answer questions regarding the design, construction, and operation of their device.

The competition itself is time-bound, giving teams 8 minutes to set up, calibrate, and launch a maximum of two shots at each target. Competition areas contain near and far targets at ground level, and specific rules govern their size and placement. Scoring is based on the accuracy of the launched projectiles, with measurements taken from the center of the targets.

Competition

From at least 75 centimeters away, students must trigger a device that drops a mass and then converts the gravitational energy of the mass to air pressure or movement, which is used to launch the projectile. The device must start at ambient air pressure (i.e., the projectile should not launch without the mass falling).

There are two targets on the course, between 2.00 m and 8.00 m from the launch area, separated by a distance of at least 2.00 m. The near target is centered on the line that bisects the launch area, parallel to the launch direction, and the far target may be anywhere up to 2.00 m from the imaginary center line. The allowed intervals at which the target areas are placed are different for regionals (0.50 m), states (0.25 m), and nationals (0.10 m).

Scoring

For each target, students may perform a maximum of two shots. The goal is to launch the projectile (i.e., tennis balls, racquetballs, ping-pong balls, or plastic practice golf balls) so that its initial impact is as close as possible to the center of the target. The maximum target score is 2000 for the near target and 4000 for the far target, minus the distance from the initial impact to the target in millimeters.

If the first shot at a target lands within 50.0 cm, a bucket shot may be requested, where a bucket is placed anywhere between 2.00 m and 8.00 m from the launch area, and 2.00 m from the imaginary center line facing up. A shot that hits the bucket is worth 200 points, and one that lands in the bottom of the bucket is 300 extra, for 500 total points per bucket, making the maximum bucket score 1000.

In addition to device accuracy at the competition, the score accounts for a graph component, in which teams are to bring graphs for determination of the best launch parameters for a maximum of 400 points.

Therefore, the score is calculated as follows:

[math]\displaystyle{ (2000-{ \text{Millimeters from near target} })+(4000-{ \text{Millimeters from far target} })+{ \text{Bucket shot bonuses} }+{ \text{Graphs score} } }[/math]

The maximum possible score is 7400.

Construction

One method to build a launch mechanism for an Air Trajectory device is to use an empty bottle (i.e. 2-liter soda bottle) and attach a pipe to it. To load it, you could put a ball in the pipe. Then you would drop your mass onto the bottle, forcing out the air inside it and launching the ball out of the tube. For this method, you would have to experiment with different masses for the short and long targets. This would not be a particularly good idea, because there is a total amount of weight you are allowed to bring in. A better way of calibration would be to change the different heights the weight is dropped from, having a standard way to measure different heights.

There are also other methods. Some involve air pumps, others use custom-made air chambers. But all of them can work- you just have to put them to the test!

Common types:

Soda Bottle - simple and easy, but can be unreliable and inconsistent
Air pump - more consistent, but more difficult to incorporate and produce the needed air pressure
Bag (of some sort) - upgraded version of soda bottle, difficult to find and incorporate
Kickball - Difficult to incorporate and prevent leaks
Custom air chamber - difficult to build, but constant and can be quite powerful

The overarching problem that can occur with all the above designs is that ping pong balls must be used which can cause deviations in mid-air from small drafts

An advanced design that some teams choose to use is employing a swinging arm to throw a ball. This design is very difficult to build, but maintains a higher level of consistency.

Factors to Consider

  • Thickness of the base of the air trajectory
  • Type of air projectile
  • Environment and conditions of competition location (ie: humidity, temperature and wind speed if the competition is outdoors)
  • Type of air pump
  • Height of mass when it is dropped
  • Size of build

Testing The Device

Testing the device is crucial to success in this event. Testing makes sure the device works as stated in the parameters. Testing should be done at many different humidities and temperatures so that these factors can be accounted for during the competition. Some regional and state competitions may have a wide range of temperatures and wind speeds if competition is outdoors, but Nationals is always done indoors in a controlled environment. Make sure that all other conditions are as close to competition conditions as possible, including using a level surface.

Consistency and reliability are the most important characteristics to strive for. The ideal device should be at a point where it hits the target every time. A device that hits the target 1 out of 3 times is unlikely to beat a device that can hit the target 9 out of 10 times. It is also important that the device is sturdy enough such that once calibration is completed, nothing will break or move (which would result in the need for re-calibration).

Tips

  • Make sure to put a ball (or whatever is being launched) in before you launch, as sometimes it can be easy to forget to reload it. An inadvertent launch will count as one of your 4 possible launches, which wastes one of the four trials.
  • While in the testing box, goggles must not be removed. Doing so will result in a large penalty.
  • Make sure that all participants' hands and knees are always out of the launching box while launching.
  • Try bringing a checklist, which can prevent the unintended omission of anything important.
  • Check your graphs, what you did before can help you during the competition.
  • Make sure to test quite a bit before competitions.
  • Before you launch, make sure to notify the judges of the impending launch.
  • Take your time - do not hurry to launch! Estimate where the projectile will land before launching.
  • Make sure to not go over the weight limit. Be especially careful if pistons are used because the piston weight counts for the falling weight.

Files

Graph Examples

Helpful Links

Official NSO Event Page
Air Trajectory for Science Olympiad
Video 1
Video 2
2014 National Tournament Trial Events
Division B: Airjectory · Bridge Building | Division C: Game On · Hydrogeology