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Rocket Flight Dynamics

Rocket Flight Dynamics. Section 1, Team 4 Student 1, Student 2, Student 3 May 5, 2008. Rockets Analyzed. Large IMU rocket Large vibration rocket Small vibration rocket All launches at Lucerne Valley dry lake bed Altitude: 2848 feet. How the RDAS functions. 6 channels of data

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Rocket Flight Dynamics

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  1. Rocket Flight Dynamics Section 1, Team 4 Student 1, Student 2, Student 3 May 5, 2008

  2. Rockets Analyzed • Large IMU rocket • Large vibration rocket • Small vibration rocket • All launches at Lucerne Valley dry lake bed • Altitude: 2848 feet

  3. How the RDAS functions • 6 channels of data • Onboard accelerometer • Onboard pressure sensor • Samples at 200 Hz • Runs on 9V battery supply

  4. IMU and Vibration Sensors • IMU • 3 MEMS Accelerometers • 3 MEMS Gyroscopes • Vibration • Piezoelectric strain gauges X axis Y axis Z axis

  5. Mode 1: Mode 2: Mode 3: . Modal Shapes • Model rocket as a uniform beam • At natural frequencies, distinct modal shapes • Values of natural frequencies depend on beam dimensions and material properties

  6. Large IMU Rocket • Launched April 26, 2008 with G339N motor • RockSim used to model launch • Estimated Apogee of 482.66 ft

  7. Large IMU Rocket • Approximations • Any point before time=0 needs to be set to zero • Account for calibration drift • Over thrust curve, all other sensors should be zero • Noisy x and z gyroscopes have negligible effect • Integration error doesn’t affect apogee

  8. Large IMU Rocket • Apogee at 5.45 seconds • Made several approximations to eliminate noise • Model only works until apogee

  9. Large Vibration Rocket • Launched April 19, 2008 with G69N motor • Severe weathercock • RockSim trajectory portrays weathercock

  10. 3 5 6 7 8 10 72.39cm 60.64cm 46.67cm 31.75cm 15.875 cm 0 cm ADC0 ADC1 ADC2 ADC3 ADC4 ADC5 Large Vibration Rocket • Six vibration sensors connected to RDAS • Sensor 10 assumed as input

  11. Large Vibration Rocket • Applied Fourier transform • Treating sensor 10 as input, plotted FRF

  12. Large Vibration Rocket • Identified three resonant peaks • Mode 1 assumed to be at 23.85 Hz

  13. Large Vibration Rocket • Mode 2 assumed to be at 0.9569 Hz

  14. Large Vibration Rocket • Higher Mode at 19.65 Hz

  15. Small Vibration Rocket • Launched April 19, 2008 with G104T motor • Camera drew power from battery • Parachute did not deploy

  16. 1 5 6 8 10 37 in 28 in 22 in 8 in 1 in ADC0 ADC1 ADC2 ADC4 ADC3 Small Vibration Rocket • Five vibration sensors connected to RDAS • Sensor 10 chosen as input

  17. Small Vibration Rocket • Applied Fourier transform and 50 Hz filter • Treating sensor 10 as input, plotted FRF

  18. Small Vibration Rocket • Identified two resonant frequency peaks • Mode 1 assumed to be at 7.997 Hz

  19. Small Vibration Rocket • Mode 2 assumed to be at 0.5831 Hz

  20. Summary • Large IMU • Apogee at 5.45 seconds • Modeled altitude at apogee of 3382 feet • Large Vibration • Three natural frequencies: 23.85 Hz, 0.956 Hz, 19.65 Hz • Small Vibration • Two natural frequencies: 7.997 Hz, 0.5831 Hz

  21. Acknowledgements • E80 lab professors • Mary Cardenas, Reza Miraghaie, Erik Spjut, Ruye Wang, and Qimin Yang • Lab proctors and Rocket Development Team • Reference 1 • Reference 2 • Reference 3

  22. References • Miraghaie, Reza, Modal Vibration, http://www.eng.hmc.edu/NewE80/PDFs/ModalVibrationLecture.pdf • Remote Data Acquisition System, http://www.aedelectronics.nl/rdas/index.htm • Spjut, Erik, http://www.eng.hmc.edu/NewE80/ • Wang, Ruye, Inertial Navigation, http://fourier.eng.hmc.edu/e80/inertialnavigation/

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