analysis of rocket flights e80 spring 2008 section 2, team 2 student 1, student 2, student 3, and...
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Analysis of Rocket Flights
E80 Spring 2008Section 2, Team 2
Student 1, Student 2, Student 3, and Student 4
Introduction
• Model and analyze the flights of four different rockets
• Three bore sizes:– Small: 2 inches– Medium: 2.25 inches– Large: 3 inches
• Three types of on-board instrumentation:– IMU navigation sensors– Temperature and pressure sensors– Vibration sensors
• Compare flight data to predictions made using RockSim
Background
• Vibration rocket – 16 Piezoelectric dynamic strain gauges
• Temperature and Pressure rocket– 4 thermistors– Pitot tube pressure sensor
• IMU rocket– 3 accelerometers on orthogonal axes
Background
• Assigned rockets– Large vibration– Large IMU– Medium temperature and pressure– Small vibration
• R-DAS acquisition system– Store data on-board (200 Hz sampling rate)– Transmit data wirelessly to a receiver (10 Hz
sampling rate)
Vibrational Analysis - Large
• Predicted modal frequencies
ModeTheoretical Frequency
(Hz)
Theoretical Aliased and Folded Frequency
(Hz)
1 ±537.97 ±62.03
2 ±1482.91 ±82.91
3 ±2907.45 ±92.55
Vibrational Analysis - Large
• Converting vibrational data to frequency domain
Vibrational Analysis - LargeFrequency Response Functions
Vibrational Analysis - Large
• Comparison of theoretical and experimental modes
ModeTheoretical Aliased
and Folded (Hz)Experimental Modes
(Hz)
1 ±62.03 ±54.8
2 ±82.91 ±68.37
3 ±92.55 ±79.64
Vibrational Analysis - Small
• Spectrum plot
IMU Analysis
• Most acceleration along z-axis
• Plotted z-axis acceleration vs. time
IMU Analysis
• Numerically integrated acceleration data to find velocity vs. time
IMU Analysis
• Numerically integrated velocity data to obtain position vs. time
IMU Analysis
• Also used pressure data to obtain a graph of position vs. time
Temperature & Pressure Analysis
• Found relationship between temperature and resistance of thermistors:
• Obtained constants during laboratory experiments
€
1
T=C1 +C2 ln(R) +C3 ln(R)
3
Temperature & Pressure Analysis
• Found relationship between height and pressure:
• Altitudes were calibrated as zero at the lake bed in Lucerne Valley
€
h = (1.4544 ×105)(1− (P
P0)0.1902)
Conclusions
• Apogee for IMU rockets approximately 130 meters
• FRFs for large vibration rockets determine how rocket responds to input frequency
• Malfunction in the small vibration rocket’s R-DAS
• Determined altitude of rocket from pressure readings
Acknowledgements
• Professor Spjut
• Professor Cardenas
• Professors Wang, Yang, and Miraghaie
• E80 Lab Proctors
• Rocket Teams
References
• Student 1, Student 2, Student 3, Student 4. Section 2 Team 2 Notebook. Spring 2008.
• E80 The Next Generation Spring 2008. Harvey Mudd College Engineering.http://www.eng.hmc.edu/NewE80/DynamicBeamLab.html.
• Elastic Properties and Young’s Modulus for Some Materials. Engineering Toolbox.
http://www.engineeringtoolbox.com/young-modulus-d_417.html.• Polycarbonate. Answers.com: Technology.
http://www.answers.com/topic/polycarbonate.
Questions?
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