Model Rocketry Honor - advanced

Arts & Crafts

Requirements

1. Have the Model Rocketry honor.

   Answer: Prerequisite: have the basic honor HM-035. Present the badge/record to the advanced instructor. — The basic Model Rocketry honor addresses the fundamentals: engine types (A/B/C), aerodynamics, parachute recovery, and launch safety. Without it, the Pathfinder has no foundation to apply to the advanced requirements that involve 2 stages, electrical launch systems, and real altitude calculations with an altimeter.

2. From a kit, assemble, launch, and recover a miniature rocket.

   Answer: Estes/Mandrake kit: assemble tube+nose cone+fins, A/B/C engine, open field, launch and recover with a parachute. — Estes Industries (USA, 1958) and Mandrake (Brazil) are the main manufacturers of kits for beginners. A8-3 engines (weaker) rise 75m; B6-4 reaches 150m; C6-5 gets to 270m. An open field should have a 100m clear radius. The parachute opens by an ejection charge 4-5 seconds after the engine burns out. Glue must dry before flight.

3. Design, build (but not from a kit), finish, and paint a single-stage rocket. Check for stability and, successfully, launch and recover this rocket.

   Answer: Design in CAD/on paper, cut, assemble, paint, do the string test (CG/CP), engine, launch, and recover. — String test: tie the rocket at the center of gravity (CG) and swing it in a circle. If the nose always points forward, it is stable. The CG must be ahead of the center of pressure (CP) by at least 1 caliber (the diameter of the tube). The OpenRocket software does pre-construction simulation, free and popular among Brazilians for easy design.

4. Do one of the following items:
   • From a kit, build, finish and paint a 2-stage rocket. Successfully launch and recover this rocket.
   • From a kit, build, finish and paint an engine of 3 stages clustered into a single rocket stage. Successfully launch and recover this rocket.

   Answer: Choose: a 2-stage rocket OR a 3-engine cluster. Assemble from the kit, paint, launch, recover with a parachute. — Two-stage rockets reach higher altitudes (300-500m) by dropping weight after the 1st burn. A cluster of 3 engines triples the initial thrust but the same altitude. The Estes V2 and Mongoose 3-stage are classic kits. Simultaneous electrical ignition requires a system with 3 parallel wires in a cluster controlled by a reliable central relay.

5. Design an electrical launch system. Once it has been approved by your instructor, build this system and use it to launch rockets at least 5 times.

   Answer: 12V battery, 5m+ wires, safety switch, launch button, igniter clips. Get it approved and launch 5x. — A standard system uses a minimum of 5m of wire for a safe distance from the operator. A safety switch prevents accidental ignition. A 12V battery (car) has a high current (50A+) to quickly heat the igniter's filament (Estes Solar Igniter or Q2G2 quick-start). Every launch must have a clear and visible countdown, ensuring safety in the field.

6. Describe and demonstrate single-station altitude tracking. With the help of an instructor, track the same rocket 3 times using 3 different engine sizes and compare altitudes with an altitude finder.

   Answer: The Estes optical altimeter (made of paper) measures the elevation angle at 100m from the pad — altitude = 100m × tan(angle). The 'Rocket Altimeter' app does the same on a phone. The A8-3 engine ~75m, B6-4 ~150m, C6-5 ~270m (an approximate 1:2:4 ratio). The results serve for a power vs altitude curve. Compare the 3 altitudes obtained.

7. Compare the speed and altitude of 2 different weights of rockets using the same engine size.

   Answer: By Newton's 2nd Law (F=ma), with the same thrust force, less mass = greater acceleration. A 30g rocket with a C6-5 engine reaches ~270m; the 60g one (double the weight) reaches only ~150m. A stopwatch measures the burn time and an optical altimeter measures the maximum altitude. An excellent practical exercise on basic classical Newtonian physics.

8. Materials: Miniature rockets should be produced only from lightweight materials such as paper, wood, plastic, and aluminum foil, with the exception of the payload supports and the mechanism, which are made of wire or similar.

   Answer: Use only lightweight materials: paper, balsa wood, plastic, and aluminum foil. Only the payload supports and the mechanism may be of metal wire. — Lightweight materials reduce kinetic energy in the case of an uncontrolled impact, increasing safety. Balsa wood weighs 0.16g/cm³ (10x less than plastic). Cardstock fins are sufficient for small rockets. Heavy metals such as steel/thick aluminum are prohibited as they increase the risk of serious injury to nearby people.

9. Mechanisms: Use only ready-made commercial miniature mechanisms, and in accordance with the manufacturer's instructions. Do not tamper with these engines and use them only for the purposes recommended by the manufacturer.

   Answer: Only ready-made engines from the manufacturer (Estes/Mandrake). Never modify, open, or mix them. The manual is mandatory. — Estes A8-3, B6-4, C6-5 engines are certified by the NAR (National Association of Rocketry). Modifying, opening, or improvising a homemade engine with gunpowder/sugar is illegal in Brazil (law 10,826) and extremely dangerous — it causes explosions. The manual indicates the delay (seconds before the ejection charge) and the class (A=2.5N·s, B=5N·s).

10. Ignition system: Launch the rockets with an electrical launch system and electrical engine 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: Electrical system + igniter + safety switch in series + button that returns to OFF automatically. Without this it is invalid. — A safety switch interlocked in series prevents ignition until it is armed. A 'momentary' button (push-to-make) returns automatically to OFF when released — preventing continuous firing. NAR Safety Code standard, item 5. Electrical igniters such as the Estes Solar and Q2G2 replaced manual fuses in the 70s for being safer and more reliable.

11. Ignition failures: If the rocket does not launch when the button on 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: Failure: remove the switch OR disconnect the battery. Wait 60s before anyone approaches the rocket. — 60 seconds is enough time to ensure the engine will not have a delayed ignition (it can light 5-30s later due to residual heating). NAR statistics show that 95% of ignition failures are a poorly connected igniter or a dead battery — correctable after the minimum safe waiting time recommended by the NAR association.

12. Launch safety: Begin a countdown before launch to ensure that everyone pays attention and maintains a safe distance of at least 4.5 meters for launches of rockets with D engines 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, check the flight stability before allowing spectators to watch the launch.

    Answer: Audible countdown. Distance: 4.5m D engine or smaller; 9.5m larger. Stability tested before an audience. — The countdown (5-4-3-2-1-IGNITION) is an international standard adopted by NASA since 1959. The distances 4.5m / 9.5m come from the NAR Safety Code, derived from tests of the post-explosion debris zone. D engines = 10-20N·s impulse (up to 270m altitude); E+ can reach 500m. Stability confirmed before any audience.

13. Launcher: Launch the rocket from a launch rod, tower, or rail, aimed within 30 degrees of vertical to ensure the rocket flies almost in a straight line, using a deflector to prevent the engine's exhaust from striking the ground. To avoid accidental eye injury, place the launchers so that the end of the launch rod is above eye level, or cap the end of the rod when it is not in use.

    Answer: Rod/tower/rail at 30° max from vertical. A deflector prevents the jet from hitting the ground. Cap the end of the rod when not in use. — A maximum tilt of 30° ensures an almost straight flight without deviating toward areas with people. A deflector (a 45° metal plate) diverts the jet horizontally, protecting the grass and ground. The standard rod is 1/8' (3.2mm) or 1/4' (6.4mm) depending on the size of the rocket. Capping the end prevents eye injuries when leaning over the launch pad when not in use.

14. 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: Limit: up to 1,500g, 125g propellant, 71.9 N·s impulse. Above 453g or 113g of propellant requires complying with federal regulations (FAA USA / DECEA Brazil). — DECEA (Department of Airspace Control) regulates amateur rockets in Brazil via ICA 100-40. A propellant of 113g+ falls into the 'High-Thrust Model' category and requires authorization. 71.9 N·s = a class G engine; above it is already advanced rocketry. The 1500g limit ensures low kinetic energy in the event of a human impact.

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

    Answer: Prohibited: strong wind, buildings/wires/trees/airport. No flammable or explosive payloads in the rocket. — Airports have a 5km exclusion zone in Brazil under ICA 100-40. Strong wind (>32km/h) deviates very light rockets toward undesired areas. Flammable payloads (paper, kerosene) or explosives (firecrackers, M-80) are prohibited by Brazilian anti-terrorism legislation. Nearby inns, hospitals, and schools should also be avoided.

16. 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 presents no risk of grass fires.

    Answer: Use an open area according to the NAR table (the radius depends on the engine). Wind ≤32km/h. No dry grass nearby. The fire risk must be nil. — The NAR (National Association of Rocketry) table recommends: engine A = 15m radius; B = 30m; C = 60m; D = 100m; E+ = 150m+. 32km/h wind is the safe limit for small models not to deviate. Dry grass catches fire easily with ejection charges at 200°C — grass fires were the #1 cause of accidents at amateur launches before the 80s.

17. Recovery system: A recovery system such as a streamer or parachute must be used on the rocket so that it returns safely and undamaged, and can then be used again. Use only flame-resistant wadding or fireproof recovery in the rocket.

    Answer: Parachute or streamer + fireproof wadding (ceramic wool). The rocket returns intact and reusable. — Ceramic wool (resistant to 1000°C+) protects the parachute from the hot ejection charges (200°C). A streamer (a long ribbon) replaces the parachute in small rockets. Estes Recovery Wadding is the American standard. Without insulation the parachute melts in mid-flight, causing a free fall that damages the rocket and the ground.

18. Recover safely: Do not attempt to recover the rocket if it falls on a power line, tall trees, or other dangerous places.

    Answer: Fell on a power line/tall tree/dangerous place: DO NOT recover it. Tell an adult. Life is worth more. — A high-voltage power line (13.8kV+) kills in milliseconds. Tall trees require professional climbing. CEMIG/CPFL have specialized teams to remove objects from the grid without shutting off the entire neighborhood. The cost of a rocket (R$50-200) is much less than a human life or hospitalization for electric shock or a fall.