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?