Overview of Hobby Rocketry

1. Overview of Hobby Rocketry Chisholm Trail Middle School November 30, 2010

2. Topics • Introductions • Rocketry Basics • Rocket Motors • Materials of Construction • Electronics

3. http://www.aarg.org/ http://groups.yahoo.com/group/rocketry-austin/

4. What Can We Learn from Rocketry? • Physics – Newton’s Laws & Laws of Motion • Aerodynamics – Stability, Drag • Electronics – Flight Computers, GPS, Telemetry • Meteorology – Wind, Air Pressure • Computers – Data Collection, Flight Simulation • Mathematics – Calculus, Trigonometry • Engineering – Problem Solving, Materials • Craftsmanship, Teamwork & Safety … and we can have fun too!

12. “L” Motor – 2,560 to 5,120 N-sec

16. Rocket Motors • General Types of Rocket Motors • Black powder (A though E motors) • APCP (Ammonium perchlorate composite propellant) • “Composite” means a mixture of fuel, oxidizer & binder • Hydrocarbon binders & metals are the fuel • Ammonium perchlorate - NH4ClO4 - is the oxidizer • Hybrid motors with PVC fuel & N2O oxidizer • Liquid-fueled motors • APCP Motors are made with Multiple “Grains” • Grain configuration controls the burn characteristics

17. Rocket Airframe Materials • In Order of Increasing Strength: • Cardboard • Phenolic cardboard • Fiberglass • Carbon fiber • Metal (aluminum) • Fiberglass with Epoxy and Carbon Fiber with Epoxy are Examples of “Composite” Materials

18. Rocketry Electronics • Altimeters • Detect apogee & break rocket apart • Deploy main parachute at low altitude • Ignite other motors (multi-stage motors & “air-starts”) • Telemetry & Rocket “Finding” Devices • Buzzers & beepers • Radio signals for directional tracking • Telemetry & GPS • Payloads • Science & meteorology experiments • Whatever else you can imagine!

19. Example GPS Flight Profile

20. Altimeter “Apogee” Detection Methods • Barometric Detection • Barometric sensor measures air pressure • Apogee is sensed when air pressure increases • Advantages – Measures actual apogee • Disadvantages – Prone to error (e.g., pressure spikes) • Accelerometer Calculation • Accelerometer measures positive “G’s” during motor burn & negative “G’s” during coast phase • Apogee is calculated when integral of positive G’s over time is equal to the integral of negative G’s • Advantages – Not sensitive to pressure variations • Disadvantages – Non-vertical flight profile

21. Barometric Pressure vs Altitude

22. Altimeter “Apogee” Detection Methods • Barometric Detection • Barometric sensor measures air pressure • Apogee is sensed when air pressure increases • Advantages – Measures actual apogee • Disadvantages – Prone to error (e.g., pressure spikes) • Accelerometer Calculation • Accelerometer measures positive “G’s” during motor burn & negative “G’s” during coast phase • Apogee is calculated when integral of positive G’s over time is equal to the integral of negative G’s • Advantages – Not sensitive to pressure variations • Disadvantages – Non-vertical flight profile

23. Example Flight Data

24. Calculating Apogee from Acceleration Data

25. Jim’s Highest Flight (So Far!) • TooCarbYen: • Two-stage rocket • Booster motor – N4000 • Sustainer motor – M1350 • Maximum Speed – Mach 2.3 (About 1,740 mph) • Altitudes: • Booster motor burnout – 5,000 feet • Sustainer motor start – 10,000 feet • Sustainer motor burnout – 20,000 feet • Maximum altitude – 55,000 feet • Recovered 3 Miles from Launch Site (via GPS)

26. TooCarbYen Before Launch