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Speed of Sound Experiment CDR. Team BalloonWorks March 29 th , 2012. Table of Contents. Introduction Mission Goal Expected Outcomes Payload Design Electrical, Software, and Mechanical Design System Testing Pre Flight Checklist Data Analysis Plan Master Budget. Mission Goal. - PowerPoint PPT Presentation
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Speed of Sound Experiment CDRTeam BalloonWorksMarch 29th, 2012
Table of Contents
• Introduction• Mission Goal• Expected Outcomes
• Payload Design• Electrical, Software, and Mechanical Design
• System Testing• Pre Flight Checklist• Data Analysis Plan• Master Budget
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.
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.
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.
System Design
Electrical Design
Electrical Design
Electrical Design
Electrical Design
Software Design• Pre-Flight Program• Sets all hardware pins and variables• Sets EEPROM address• Sets RTC
Initialize all hardware pins and declare all
variables
Initiate EEPROM address to 0
Set RTC to desired HH:MM:SS
Display
Read the address from the EEPROM on the BASIC Stamp
Write counter data to EEPROM
Write RTC data to EEPROM Get hour, minute, and second from RTC
Start the counter to count until the arrival of the pulse
Is EEPOM ADDR>=max
EEPROM Address
Send a 40kHz pulse
Check comparator statusGet counter data
Reset the counters
Pause in order to maintain consistent data acquisition of
every fifteen seconds
End Program
Yes
No
Write address to the EEPROM on the BASIC Stamp
Run the term232 program to save data into a file
Display the data showing the address as well as the values
Retrieve the data for the EEPROM
Pause
Is EEPOM ADDR>=max
EEPROM Address
End Program
Yes
No
Post-Flight Program
Mechanical Design• Hexagonal Design• Extruded polystyrene rigid foam
insulation material
Mechanical DesignUnits in mm
Components Weight
Payload Structure 165g +/- 5g (Measured)
BalloonSat Circuit Board 70g +/- 0.5g (Measured)
Testing Circuit Board 60g +/- 5g (Measured&Apptoximated)
Batteries 115g +/- 0.5g (Calculated)
Supports 60g +/- 5g (Approximated)
Total 470g
Weight Budget
System Testing• Wind Test• Determine whether the mechanical design would effectively
block the wind effects on speed of sound• Air Blower, Oscilloscope, Test Circuit, Prototype Box• Successful
• Vacuum Test• Determine the maximum altitude the receiver can detect the
ultrasonic pulse• Vacuum Chamber, Oscilloscope, Test Circuit• Successful to 29,410 m
System Testing
System Testing• Temperature Test• Determine whether the experiment chamber maintains
a thermal equilibrium with the surroundings.• Two HOBOS with temperature probes and prototype box• Successful
• Electronics Test• Prove that the test circuit can store the counts to the
EEPROM and that the post flight software can retrieve the counts.
• Test Circuit, Pre/Flight/Post software, PC.• In progress
System Testing
Pre Flight Checklist• Calibration: Sync RTC time with the LaACES GPS beacon time
the morning of the launch.Time (min) Procedure
5 Fresh batteries installation and perform voltage checks
5 Load preflight and flight software
5 Secure test circuit and BalloonSat slider to the payload
10 Close top cover and secure payload to strings
Total=25
Data Analysis Plan• Post Flight Software will retrieve the data stored during flight.• Excel will:• Convert the counts to decimal numbers. • Multiply by 1/f of the timing oscillator (10 MHz) to obtain the
time the sound pulse took to get from the Tx to the Rx• Divide 0.19 m by the above time to get speed of sound.
• Obtain temperature, pressure, and relative humidity data from Team Flyboys.
• Obtain altitude vs. time data from LaACES.• Construct graphs of speed of sound vs. altitude.• Construct graph of measured speed of sound vs. theoretical
speed of sound.
Master BudgetQuantity Description or Part Number Price Expected
Arrival
1 CD4011UBE $0.38 01 CD4049UBE $0.52 02 255-400SR12M-ROX $5.24 0
2 and 10 Precision resistor Z201 and capacitor E4941
$41.74 4/2
1 AD822ANZ $6.54 01 LM311N $0.56 01 MXO45T-3C-10M0000 $2.31 01 MCP23017-E/SP $1.44 02 SN74HC590AN $0.66 036 Energizer Ultimate Lithium AAA Batteries $80.1 4/2
1 Test Circuit PCB Board $170.00 4/2Total $309.49