Projectile Safety

Projectile-based investigations, including activities involving springs, compressed air, elastic force, rolling objects, or launched materials, can support meaningful learning in physics and engineering. These activities also present potential hazards related to impact, misfires, equipment failure, and unintended movement. All projectile activities should be preceded by a hazard analysis and risk assessment and should be closely supervised by the teacher.

Students should receive explicit safety instructions before beginning any projectile activity and should follow all classroom safety and behavior expectations, including the use of appropriate eye protection. Launching devices must be stable, used only as designed, and aimed away from people at all times. Projectiles must never be directed toward students, staff, visitors, or unintended areas.

Projectile investigations should be conducted in a space with clear boundaries, adequate distance between the launch area and observers, and no unnecessary obstructions. Barriers, shields, or designated safety zones should be used when needed to reduce the risk of injury. Teachers should also establish procedures for misfires, malfunctioning equipment, or unexpected launches, including when students must stop work, step back, and notify the teacher before continuing.

Safety Precautions for Rocket Launchings on School Sites

Rocket launchings provide one engaging opportunity to investigate many elements of physical science and engineering, including forces and motion, pressure, aerodynamics, and the engineering design process. While rocket launchings are commonly performed, educators should conduct thorough hazard analysis and risk assessment and develop a safety plan, clearly communicated to students. As with any other hands-on activity or demonstration, the teacher should evaluate whether a rocket launch will specifically support measurable learning goals, and if the appropriate safety considerations are in place. Otherwise, an alternative activity should be considered.

Always wear appropriate eye protection during rocket launchings. Refer to the Outdoor Science Education section for additional guidance in planning for a rocket launch using an outdoor learning space.

Solid Propellant Model Rockets

Model rocket activities may be conducted on school sites only when permitted by applicable law, district policy, and the local fire authority. Activities involving solid propellant model rockets should be carefully planned, limited to authorized classes or clubs, and conducted under the supervision of qualified adults. When an audience is present, schools should consider limiting the number of launches to reduce crowding and support safe supervision.

For school-based activities, model rockets should use only approved, commercially manufactured, solid propellant engines and should meet all applicable size, weight, material, and configuration requirements established by the permitting authority. Rockets with smaller engines are recommended for instructional use. Rockets should not contain metal parts, and all rocket materials, engines, and recovery systems should be inspected before launch.

Schools should obtain required approvals before launching model rockets. This may include submitting a launch request to the responsible district office and obtaining a permit from the local fire department or authority having jurisdiction. The permit should be issued to the appropriate school administrator, and the instructor responsible for the activity should conduct the launch in accordance with all safety standards, permit conditions, district procedures, and administrative expectations.

The launch site should include a clearly identified firing area and recovery area. The site should provide adequate distance from spectators, property boundaries, buildings, vehicles, high-voltage lines, major roads, dry grass, brush, wooded areas, or other hazards identified by the fire authority or through the activity’s hazard analysis and risk assessment. The firing area should be marked or blocked off with rope, cones, or other temporary barriers, and observers should remain outside the designated safety zone.

Model rockets should be launched only from a stable launch platform equipped with an appropriate launch guide to support stable flight. Ignition should be conducted remotely by electrical means and controlled only by the designated person launching the rocket, under the supervision of the instructor in charge. The launch angle, weather conditions, wind speed, visibility, and daylight requirements should comply with permit conditions and established safety procedures. Recovery devices should be made of flame-resistant material.

All personnel and spectators should maintain the required safe distance from the launch platform during countdown and launch and should be positioned in a location that reduces exposure to launch or recovery hazards. Spectators should remain upwind of the firing area when appropriate. Vehicles should not be located within the firing area, and only the designated launch power source should be used at the launch site.

The instructor in charge should supervise engine installation, launch preparation, countdown, firing, recovery procedures, and the handling or disposal of unfired or defective rocket engines. A second adult should be assigned to monitor spectators and other persons present. Students should receive explicit safety instruction before the activity and should understand that rockets must never be aimed at people, animals, buildings, vehicles, or unintended areas.

If a misfire occurs, no one should approach the rocket immediately. The rocket should remain in the launch position for at least one full minute, or longer if required by the manufacturer, permit, or local procedure, before it is approached. Disarming should occur only under the direct supervision of the instructor in charge, and the person checking the misfire should wear appropriate face and eye protection.

Water Rockets

Water rocket activities can support meaningful learning about forces, motion, pressure, and engineering design; however, pressurized water rockets are not toys and must be treated as potentially hazardous devices. A pressurized rocket can store significant energy, travel at high speed, burst unexpectedly, or land far from the launch site. Water rocket activities should be preceded by a hazard analysis and risk assessment and conducted only under constant adult supervision. Schools should follow applicable local laws, district policies, and site procedures. Only ordinary tap water should be used as the pressurizing fluid; substances that are harmful to people or the environment should not be used.

Water rockets should be constructed from lightweight, nonmetallic materials. Nose cones, fins, payload containers, and other external parts should not contain metal or other conductive materials. Glass, brittle plastic, or other breakable containers should never be used. Pressure chambers should be limited to carbonated beverage bottles or other containers specifically designed to withstand the anticipated launch pressure. All materials should be inspected before launch for cracks, damage, weak attachment points, or other unsafe conditions.

Any payload section should be constructed from strong, lightweight, nonmetallic materials and attached above the pressurized portion of the rocket. Payloads should be separate from the pressure chamber and should not include exposed metal parts. Flammable, explosive, pyrotechnic, biohazardous, toxic, corrosive, or environmentally harmful materials must not be used as payloads. Live animals should never be used as payloads.

A recovery system should be used for any rocket or rocket component expected to travel above 20 feet in altitude, including any parts that separate or are released during flight. The recovery system should slow descent to reduce the likelihood of injury or damage from falling rockets, debris, or components. Recovery systems should not contain black powder, fireworks, pyrotechnic devices, or other explosive materials.

Launch areas should be selected to provide adequate clearance from spectators, buildings, vehicles, roads, power lines, trees, dry vegetation, and other hazards. Spectators should remain behind a clearly marked boundary at a safe distance from the launch site and recovery area. Rockets should never be aimed at people, animals, buildings, vehicles, or unintended areas. If a launch misfires, leaks, or malfunctions, students should not approach the rocket until the teacher determines it is safe to do so and the pressure has been released according to established procedures.

Pressure Vessel Requirements for Rockets

The pressure vessel for a rocket should be made from thin, ductile plastic that is capable of withstanding the intended launch pressure. Pressure vessels should not be constructed from, or modified using, any portion of an existing high-pressure enclosure. The pressure vessel and all external rocket components should be nonmetallic to reduce hazards from falling parts, failed recovery systems, contact with power lines, or projectile fragments if the vessel fails.

Metal components should not be attached to or placed in contact with the outside of the pressure vessel because they may become dangerous projectiles if the vessel bursts. All pressure vessels should be inspected before use for cracks, dents, deformation, weakened seams, or other damage. Damaged or questionable vessels should not be pressurized or launched.

Pressure testing should be conducted only under adult supervision and should be completed by filling the vessel completely with water before pressurizing the system. A protective barrier should be used during testing to reduce the risk of injury if the vessel bursts. Water rockets should be pressurized only with atmospheric air; exotic gases, cryogenic materials, combustible gases, or other pressurizing agents should not be used.

Launcher Requirements for Rockets

Rockets should be launched only from a stable launch device designed to hold the rocket securely during pressurization and release. The launcher should be positioned so the rocket is aimed nearly vertical, within 30 degrees of vertical, to reduce the likelihood of unintended horizontal travel.

Rockets must be pressurized and launched remotely. Students, operators, and spectators should remain at a safe distance from any pressurized rocket because a pressure vessel can rupture and cause serious injury. Flight crew members should stand at least 50 feet from the pressurized rocket during launch, and spectators should be positioned farther back and behind the flight crew.

The launch area should be clearly marked, and no one should approach the rocket while it is pressurized. If a malfunction, leak, or misfire occurs, students should remain behind the safety boundary until the teacher or designated adult determines that the system has been depressurized and is safe to approach.

Pressure Source for Rockets

All valves, hoses, pipes, fittings, and connectors between the pressure source and the launch pad should be rated for the planned launch pressure and inspected before use. Components that are damaged, leaking, improperly fitted, or not rated for the intended pressure should not be used.

Rockets should be pressurized only with atmospheric air. Compressed gases other than air, combustible gases, cryogenic materials, or other pressurizing agents should not be used.

Flight Safety for Rockets

Rockets should be launched only outdoors in a clear, open area that is free from trees, power lines, buildings, vehicles, roadways, and other obstacles. The launch site should be selected to provide adequate space for both launch and recovery and to prevent rockets from traveling into areas where people, vehicles, or property may be at risk.

An audible countdown should be used before each launch so that all participants and observers are aware that the rocket is about to be released. Launches should occur only under safe weather conditions, including wind speeds no greater than 15 miles per hour, and should be postponed if visibility, wind, lightning, rain, or other conditions create additional hazards.

Rockets should never be launched over or near roadways, parking areas, or into the path of vehicles. Students should not attempt to recover rockets from power lines, tall trees, rooftops, roadways, water, or any other dangerous or inaccessible location. Recovery should occur only when the teacher or designated adult determines that it is safe to enter the recovery area.