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Speed of Sound Experiment Pre-CDR

Speed of Sound Experiment Pre-CDR. Team BalloonWorks. Table of Contents. Introduction Mission Goal Expected Outcomes Mission Requirements Payload Design Electrical, Software, and Mechanical Design Risk Management. Introduction. Mission Goal.

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Speed of Sound Experiment Pre-CDR

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  1. Speed of Sound Experiment Pre-CDR Team BalloonWorks

  2. Table of Contents • Introduction • Mission Goal • Expected Outcomes • Mission Requirements • Payload Design • Electrical, Software, and Mechanical Design • Risk Management

  3. Introduction

  4. Mission Goal To measure the speed of sound in Earth’s atmosphere in order to establish a relationship between speed of sound and altitude up to 30,480 meters and to consider the effects of atmospheric properties on the speed of sound.

  5. Expected Outcomes • Speed of sound is primarily dependent on temperature. • Speed of sound will decrease until the balloon reaches the tropopause. • Speed of sound remain constant in the tropopause. • Speed of sound will increase in the stratosphere. • Humidity is expected to play a minor role in determining the speed of sound when compared to temperature changes.

  6. Mission Requirements • Team BalloonWorks and the payload shall comply with all LaACES requirements. • The payload shall measure the speed of sound in ambient atmospheric conditions in order to construct a profile of the speed of sound versus altitude. • The payload shall obtain temperature, pressure and humidity to verify the data gathered on the speed of sound. • Team BalloonWorks shall retrieve and analyze data post flight.

  7. Payload Design

  8. Principle of Operation • Ultrasonic transmitter will emit an ultrasonic pulse. • Receiver will detect the pulse after it travels through ambient air. • Test circuit will determine the time it takes for the pulse to travel the fixed distance between transmitter and receiver. • Payload will have both an experiment and circuitry chamber. • Experiment chamber will allow temperature inside to be equal to ambient temperature and will contain the transmitter and receiver. • Circuitry chamber will be closed to the environment and will hold the power supply, test circuit, and BalloonSat.

  9. System Design

  10. Electrical Design • Main Components • BASIC Stamp • RTC • EEPROM • Transmitter • Receiver • Test Circuit • Driver • Op-amp • Comparator • Flip-Flop • Oscillator • 2 Stage Counters • I/O Expander • Power Supply

  11. Test Circuit • Driver • Op-amp • Comparator • Flip-Flop • Oscillator • 2 Stage Counters • I/O Expander

  12. Power Budget • 5 V input to all components after regulation • Maximum supply currents • 4 hours time

  13. Power Supply • 8 Energizer Ultimate Lithium AA Batteries in series to output 12 V to the BalloonSat and test circuit. • Both BalloonSat and test circuit require 5 V. BalloonSat has a voltage regulator (U3). Test circuit will have a voltage regulator. • U3 and test circuit’s voltage regulator will need to be in parallel with the batteries. • Every component in the test circuit will need to be in parallel with the test circuit’s voltage regulator but not with the batteries.

  14. Power Supply • Per Battery: 500 mA, 2000 mA-hrs

  15. Initialize all hardware pins and declare all variables Software Design Initiate EEPROM address to 0 • Pre-Flight Program • Sets all hardware pins and variables • Sets EEPROM address • Sets RTC Set RTC to desired HH:MM:SS Display

  16. Read the address from the EEPROM on the BASIC Stamp FlightProgram Is EEPOM ADDR>=max EEPROM Address Yes End Program No Write_To_EEPROM Sub-Routine Get_Time Sub-Routine Switch the set pin on the Flip-Flop from high to low and then back to high Send a 40kHz pulse Counter Sub-Routine Comparator_Status Sub-Routine Write address to the EEPROM on the BASIC Stamp Reset the counters Write_To_EEPROM Sub-Routine Pause in order to maintain consistent data acquisition of every fifteen seconds

  17. Get_Time: Comparator_Status: Counter: Write_To_EEPROM: Flight Program-Subroutines Turn RTCand SCLK pins low I2COUT command I2COUT command Enter DO loop Bring RTCpin high I2CIN command Pause Yes Comp=1 Transmit to Stamp Pause Return No Turn RTCpin back to low Return Loop Return Return

  18. Run the term232 program to save data into a file Is EEPOM ADDR>=max EEPROM Address Post-Flight Program Yes End Program No Use the I2CIN command to retrieve the data for the EEPROM Display the data showing the address as well as the values Pause

  19. Mechanical Design • Purpose of Mechanical Design • Hexagonal Design • Extruded polystyrene rigid foam insulation material

  20. Experiment Chamber and Circuitry Chamber Design

  21. Circuitry Embracement and Battery Holder Design

  22. Top Cover

  23. Weight Budget

  24. Risk Management

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