Model Rocketry Honor

Arts & Crafts

Requirements

1. Explain the Model Rocketry safety code.

   Answer: Safety code: use certified motors (NAR), launch only in an open and dry field, keep a minimum distance from the public, do not launch near planes/poles, use a parachute for recovery, check the wind and rain forecast, and have a fire extinguisher nearby. NAR (USA) standard and MEC for schools. — NAR (National Association of Rocketry, USA) and Tripoli are the certifying bodies for amateur rocket motors; in Brazil, amateur rocketry follows the standards of the AEB (Brazilian Space Agency), and there are events such as MOBFOG (Brazilian Rocket Olympiad) that teach the safety code to students.

2. Explain the importance of the basic components of model rockets.

   Answer: Main components: aerodynamic nose cone (penetrates the air), cylindrical body (structure), fins (directional stability), motor (thrust), motor retainer, parachute/recovery system (safe descent), and launch tube. Each one fulfills a specific function for stable flight and safe recovery. — Fins ensure aerodynamic stability — without them the rocket tumbles or falls out of control; the conical nose was discovered experimentally to be the best for subsonic flight. The retainer keeps the motor fixed in the body during the burn and releases it at the moment of ejection; the launch tube stabilizes the initial liftoff.

3. Draw the following:
   • The flight stages of a model rocket.
   • A cross-section of a model rocket, identifying each part.
   • A schematic diagram of a simple launch system, using the appropriate electrical symbols.

   Answer: You must draw three things: (1) the steps of the flight (ignition, liftoff, apogee, parachute ejection, descent); (2) a cross-section of the rocket identifying the nose, body, motor, recovery system, and fins; (3) a schematic plan of the electrical launch system with battery, switch, and igniter. — The flight of a typical amateur rocket lasts 30-60 seconds: 1-3 s of thrust (motor burns), up to 10 s of coasting (rising by inertia), apogee, ejection, and 30-60s of descent with a parachute. Electrical symbols: battery (||−|), switch (\), igniter (resistor R) — IEC/IEEE standard.

4. Define the following:
   • Wadding
   • Boost gliders
   • Simulator
   • Payload
   • Apogee
   • Center of gravity
   • Center of pressure
   • Thrust
   • Velocity
   • Ejection

   Answer: 1) Wadding: a soft material (fireproof paper wadding or padding) placed in the rocket to protect the parachute and the payload from the heat and hot gases of the ejection charge, cushioning and insulating. 2) Boost gliders: rockets (or part of them) that, after the motor burns out, transform into a glider, descending by gliding through the air instead of falling by parachute. 3) Simulator: a computer program that calculates and predicts the rocket's flight (altitude, speed, stability) from the model and the motor, before the actual launch. 4) Payload: any additional item that the rocket carries beyond its structure, such as instruments, a camera, sensors, or a small experimental object. 5) Apogee: the highest point of the trajectory, the maximum altitude that the rocket reaches before beginning to descend. 6) Center of gravity (CG): the point where the rocket's weight is concentrated, around which it balances and rotates. 7) Center of pressure (CP): the point where the sum of the aerodynamic forces (from the air) on the rocket in flight is concentrated. To be stable, the CP must be behind the CG. 8) Impulse: the force that the motor produces to push the rocket; measured over time, it is what determines how much the rocket accelerates and rises. 9) Speed: the rapidity with which the rocket moves, that is, the distance covered in a given time. 10) Ejection: the action of the motor's ejection charge that, at apogee, expels the cone/opens the compartment and releases the parachute (or activates the glider) for a safe descent. — OpenRocket and RockSim are popular simulators (free and paid); for aerodynamic stability, the center of gravity MUST be in front of the center of pressure (the caliber rule) — otherwise the rocket tumbles. The apogee of a typical amateur rocket is between 50-300 meters depending on the motor used.

5. Name and describe at least 4 different recovery systems.

   Answer: Four recovery systems: parachute (most common, opens and descends slowly); streamer (a long ribbon that increases drag); tumble (the rocket falls spinning randomly in loose pieces); glide (turns into a glider after apogee); helicopter (rotors spin during the fall). Choose according to the size and weight of the rocket. — Parachute is the standard for rockets over 50g; streamer is used in small models (such as MicroMaxx); tumble works on light single-stage rockets (mass <30g) where it is enough for the body to fall spinning; glide and helicopter are advanced techniques seen in international NAR and Tripoli competitions.

6. From a kit, assemble, finish, and paint a single-stage rocket that has a minimum length of 15 cm. Launch the rocket with a parachute or another recovery system.

   Answer: Buy a ready-made kit (Estes, Apogee, Quest), assemble it according to the instructions (glue, sand, paint), with a minimum length of 15 cm. Do the finishing and creative painting, install the parachute/recovery system. Launch in an open field, with a certified motor, on a windless day. Recover it and present it to the instructor. — Estes kits (the most popular brand in the world) range from US$ 15 to 60 and take 4-8 hours to assemble; the typical length is 30-50 cm — 15 cm is the minimum of the requirement. Use a suitable motor according to the kit manual (usually A8-3, B6-4, or C6-5) and a wide launch site (an empty soccer field is ideal).

7. Materials: Model rockets must be produced only from lightweight materials such as paper, wood, plastic, and aluminum foil, with the exception of the load supports and the mechanism, made of wire or similar.

   Answer: The permitted materials are lightweight: cardstock, balsa wood, plastic (PET), and aluminum foil. Load supports and retention mechanisms can be of thin wire or similar. Heavy materials such as solid metal, lead, or concrete are prohibited for safety reasons and by the NAR standard. — Balsa wood is preferred because it is extremely light (density 0.16 g/cm³) and strong; bottle PET works for the nose and large fins; cardstock forms the body of many amateur rockets. Extra weights should be fixed at the tip with caulking putty to adjust the center of gravity.

8. Mechanisms: Use only model mechanisms bought ready-made, and in accordance with the manufacturer's instructions. Do not tamper with these motors and use them only for the purposes recommended by the manufacturer.

   Answer: The motors must be bought ready-made from certified manufacturers (Estes, Aerotech) — never homemade or modified. Use them exactly according to the manufacturer's instructions and always for the recommended purposes (a class D motor only in class D rockets, etc.). Tampering with the motor or changing its contents is dangerous and prohibited by the NAR. — Homemade motors are the #1 cause of accidents in amateur rocketry — improvised gunpowder explodes unpredictably; certified motors undergo rigorous NAR/Tripoli testing and have classes (A, B, C, D, E, etc.) with a standardized total impulse. Each motor has an expiration date printed on the original packaging.

9. Ignition system: Launch the rockets with an electrical launch system and electrical motor igniters. The launch system must have a safety interlock in series with the launch switch, using a launch switch that returns to the "OFF" position when released.

   Answer: The ignition system must be electrical, with certified electrical igniters. The launcher needs to have a safety interlock in series with the launch button; the switch must automatically return to 'OFF' after launching (return spring). A 12V external battery, out of reach of nearby spectators. — The safety interlock (a physical key separate from the button) prevents accidental activation — the button works only with the interlock engaged; the automatic return to 'OFF' (a dead-man type button) prevents the circuit from staying closed even if the operator lets go. The battery is at least 5 meters from the rocket for safety.

10. Ignition failures: If the rocket does not launch when the button of the electrical launch system is pressed, you must remove it from the safety-interlock launcher or disconnect the battery, and wait 60 seconds after the last launch before allowing anyone to approach the rocket.

    Answer: If the rocket does not launch when the button is pressed: engage the safety interlock/disconnect the battery; wait 60 seconds after the last attempt; only then can someone approach the rocket (the motor may fire with a delay); check the igniter and the connections before attempting the launch again. — Waiting 60 seconds is a critical rule — many motor explosions in the face have occurred because the user approached right after a failure; a motor with a 'hangfire' (delayed burn) can still detonate 30-45 seconds later; the igniter may have a simple failure (poor contact) that is fixed without a new motor.

11. Safety launch: Begin a countdown before the launch to ensure that everyone pays attention and keeps a safe distance of at least 4.5 meters for launches of rockets with D motors or smaller, and 9.5 meters for launches of larger rockets. If the rocket has not been tested and there is uncertainty about its safety or stability, verify the flight stability before allowing spectators to watch the launch.

    Answer: Before launching: do an audible countdown (5,4,3,2,1) to alert everyone. Minimum distance from the public: 4.5 m for rockets with a D motor or smaller; 9.5 m for larger motors. If the rocket is new or untested, check the flight stability before allowing spectators nearby, for safety. — The countdown (a NASA heritage) ensures collective attention and time to abort the launch if something wrong is noticed; homemade stability tests include the string test (tie the rocket and swing it — it must not tumble) and a simulation test in OpenRocket; the NAR standard requires even greater distances for E+ motors.

12. Launcher: Launch the rocket from a launch rod, tower, or rail, pointed within 30 degrees of vertical to ensure that the rocket flies nearly in a straight line, using a deflector to prevent the motor's blast from hitting the ground. To avoid accidental eye injury, place the launchers so that the tip of the launch rod is above eye level, or cap the tip of the rod when not in use.

    Answer: Use a launch rod, tower, or rail inclined up to 30 degrees from vertical so the rocket flies nearly straight. Place a deflector below to prevent the motor's blast from hitting the ground. To avoid eye injury, put the tip of the rod above eye level or cap it when not in use. — A 3-5 mm stainless steel rod is the most common launcher for amateur rockets; an angle of up to 30° ensures that the rocket flies in the intended direction and lands outside the spectator area. A blast deflector protects the grass from fire and the motor from a return flow of gases.

13. Size: The model rocket will not weigh more than 1,500 grams at launch and will not contain more than 125 grams of propellant or 71.9 seconds of total impulse. If the model rocket weighs more than 453 grams at liftoff or has more than 113 grams of propellant, check and comply with the Federal Aviation Administration regulations before flying.

    Answer: The rocket cannot weigh more than 1,500 g with the motor ready, nor have more than 125 g of propellant or 71.9 seconds of total impulse. If it has more than 453 g of total mass or 113 g of propellant, check the FAA (federal aviation authority) regulations before flying — they require special permission. — These limits are FAA (USA) regulations — FAR Part 101 — which define 'class 1' rockets (up to 453 g and 113 g of propellant, free flight) vs 'class 2' (above that, requiring prior notification). In Brazil, ANAC and DECEA control amateur air launches above these limits with similar rules.

14. Flight safety: Do not launch the rocket against strong winds, near buildings, power lines, tall trees, near airports or heliports (where aircraft fly low), or in any conditions that could be dangerous to people or property, and do not place any flammable or explosive load in the rocket.

    Answer: Do not launch against strong winds, near buildings, power lines, tall trees, airports/heliports, or in conditions dangerous to people or property. Do not place flammable or explosive loads in the rocket (prohibited by the NAR and ANAC aviation legislation). Always check the surroundings before launching. — Launching near an airport can cause a very serious air accident — controlled airspace has a minimum radius of 9 km from the airport; tall trees and power lines cause loss of the rocket and electrical risk; wind >32 km/h takes the rocket off course. Extra explosive loads turn the rocket into a weapon — a federal crime.

15. Launch area: Only launch the rocket in an open area at least as large as shown in the table ( http://nar.org/NARmrsc.html), and in safe weather conditions, with wind speeds no greater than 32km/h. Make sure there is no dry grass near the launch pad, and that the launch site does not present a risk of grass fires.

    Answer: Launch only in an open area of minimum size according to the NAR table (http://nar.org/NARmrsc.html), with wind up to 32 km/h and safe weather. Confirm that there is no dry grass near the pad to avoid the risk of a grass fire on the field during the amateur rocket launch at the club. — The NAR minimum-area table scales with the motor class: class A needs a small soccer field (60x80 m); class E requires 800x800 m. Wind >32 km/h takes the rocket off course; dry grass + a motor spark = a fast fire (lessons from the 2018 Camp Fire, California). Always have a fire extinguisher nearby.

16. Recovery system: A recovery system such as a streamer or parachute must be used on the rocket so that it returns safely and without damage, and can then be used again. Use only flame-resistant wadding or fireproof recovery in the rocket.

    Answer: Use a recovery system (parachute, streamer) so that the rocket returns safely and without damage, and can be reused. Use only flame-resistant wadding or fireproof material in the recovery to avoid the parachute catching fire during ejection by the motor's hot gases. — The parachute is ejected by the hot gases of the motor's ejection charge (about 250°C); without fireproof wadding (flame-treated cotton, archival paper), the parachute can catch fire and the rocket can fall in free fall, destroying the work — flame-proof wadding is mandatory in Estes and similar kits.

17. Safe recovery: Do not attempt to recover the rocket if it falls onto a power line, tall trees, or other dangerous places.

    Answer: Do not try to recover a rocket that falls onto a power line, tall trees, roofs, deep water, or dangerous places. Notify the owner, call the power company (if on a line), or accept the loss. The Pathfinder's life is worth more than the rocket — electrical risk, falling from a height, or wild animals are real. — Accidents during rocket recovery include fatal electric shocks (high-voltage lines), falls from trees or roofs (spinal injuries), and animal attacks. The NAR rule is clear: 'recover safely or lose the rocket' — manufacturers keep kit prices affordable precisely because rockets can be lost.