Speed of Sound Team BalloonWorks. Table of Contents Mission Goal and Objectives Science and...
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Transcript of Speed of Sound Team BalloonWorks. Table of Contents Mission Goal and Objectives Science and...
Speed of Sound
Team BalloonWorks
Table of Contents
• Mission Goal and Objectives• Science and Technical Backgrounds• Mission Requirements• Payload Design• Payload Development Plan• Project Management• Master Schedule• Risk Management and Contingency
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 an altitude of 30,480 meters and to consider the effects of atmospheric properties on the speed of sound.
Science Objectives
• Determine the profile of the speed of sound with altitude.• Determine the general profile of temperature
with altitude.• Determine the relationship between
temperature and speed of sound.• Determine the effects of humidity on the speed
of sound.
Technical Objectives
• Obtain accurate and precise measurements for speed of sound.• Obtain accurate and precise measurements for
temperature, pressure, and humidity.• Operate in expected atmospheric conditions.• Obtain data post-flight and be able to analyze
the data retrieved.• Complete all required flight documents such as
the PDR, CDR, and FRR.
Science Background
Earth’s Atmosphere
• Troposphere• Surface to ≈ 12 km• Temperature decreases
• Stratosphere• ≈ 20 to 50 km• Temperature increases
• Mesosphere• Thermosphere• Exosphere
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.
Technical Background
Temperature Sensor
• Required Range: -70 ˚C to 38 ˚C• BalloonSat’s AD780 (U5)• -55 ˚C to 120 ˚C
• Resistive Temperature Detector (RTD)• -200 ˚C to 650 ˚C
• Thermocouples• -270 ˚C to 2000 ˚C
• Thermistor• -80 ˚C to 120 ˚C
Pressure and RH Sensors
• Required Range: 10 hPa to 1020 hPa• ICS1210 Model• Sensor interfacing exercise• Has already been tested• Piezoresistive-type sensor
• Required Range: 0 %RH to 100%RH• Resistive RH Sensor• -40 °C to 100 °C• 0 %RH to 100 %RH
• Capacitive RH Sensor• -80 °C to 150 °C• 0 %RH to 100 %RH
Speed of Sound Apparatus
• 20 to 30 measurements on the ascent will be necessary to reproduce profile• If 25 measurements are taken
during ascent:• 4 min between each
measurement• Based on a 305 meters/min
ascent rate and a 100 min ascent time
• Payload will still continue to take measurements during descent
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 measure temperature,
pressure and humidity to verify the data gathered on the speed of sound.• Team BalloonWorks shall retrieve and analyze
data post flight.
Payload Design
Principle of Operation
• The main objective of the payload will be to measure the speed of sound during the flight. • In order to obtain an accurate speed of sound
profile with respect to altitude, temperature, pressure, and relative humidity sensors will operate in the same environment as the speed of sound apparatus.
System Design
Sensors• Temperature: 44000 Series Thermistor
• -80 °C to 120 °C• ± 0.2 °C
• Pressure: ICS1210
• 0 hPa to 6900 hPa• -40 °C to 125 °C• ± 1.0 %
• RH: P-14 Rapid Capacitive RH Sensor
• 0 %RH to 100 %RH• -80 °C to 150 °C• ± 1.5 %
• Measurement Specialties, Inc. (2003). IC Sensors Product Databook, p. 18. Retrieved from http://nees.berkeley.edu/Facilities/pdf/Instrumentation/ic_sensors_catalog.pdf
Sensor Interfacing• Temperature Sensor:
• Pressure Sensor:
Sensor Interfacing• RH Sensor:
Control Electronics
Power Supply
Power Budget
Component Voltage (V)Current (mA)
Power (mW)
Charge (mA-hours)
Energy (mW-hours)
RH Sensor 12 ≈2.0 ≈24 ≈8 ≈96
Thermistor 12 0.015 0.18 0.06 0.72
Pressure Sensor
12 2.0 24 896
Speaker 1.5 35 52.5 140 210
Field Recorder
3 ≈100 ≈300 ≈400≈1200
BalloonSat 12 ≈80 ≈960 ≈320 ≈3840
Total Needed
12 219.015 1360.68 876.065442.72
Power Budget
Software Design• Data Format and Storage• BASIC Stamp Editor Version 2.5 • RTC• Time interval between measurements• Time stamp is formatted as a hexadecimal number • Digital Sensor Data• Counter• Data Point requires 1 byte per unit data: Temperature, Pressure,
RH, Hour, Minute, Second• On Board storage must be greater than 540 bytes• Speed of Sound Apparatus
Initialize all hardware pins and declare all
variables
Initiate EEPROM address to 0
Write to EEPROM in increments of EEPROM
Address
Write to EEPROM in increments of EEPROM
Address
End Program
Get RTC hour, minute, second values
Get ADC channel 0, 1, and 2 values
Is EEPOM ADDR>=max
EEPROM Address
Thermal Design
• -70 °C to 38 °C• Box built from LaACES foam material• Should keep closed compartment at T > -10 °C• Heat by electronics will help
• Open compartment will remain at ambient conditions
Mechanical Design
• External Design• Rectangular: 25 cm by 10 cm by 10 cm• 0.636 cm thick• 17 cm separation for strings• Plastic mesh covering 20% of bottom face area to
allow open compartment
Mechanical Design
• Internal Design• Open Compartment• T, RH, Speaker, Recorder• Reflecting Arc
• Closed Compartment• Pressure Sensor• Sensors’ Conditioning Circuitry• BalloonSat• Power Supply
Weight Budget
Component Weight Budget Estimate (g)
Box 100
BalloonSat 65
Sensors, Speaker and Conditioning Circuitry
≈40
Recorder 180
Power Supply 115
Total 500
Payload Development Plan
• Electrical Design Development • Software Design Development• Mechanical Design Development• Mission Development
Project Management
Team Responsibility and contact information
• Team Contract• Configuration Management Plan • Interface Control
WBS
Project Timeline and Milestones
Risk ManagementRisk Event Likelihood Impact Detection
DifficultyWhen
Loss of payload 3 5 5 Post-Flight
Component Failure 4 4 2 During Flight/Testing
Incorrect code 2 4 1 CalibrationPart unavailability 3 3 2 Pre-Flight
Internal deadlines not met
4 4 3 Pre-Flight
Team member refusing to cooperate
2 4 1 Pre-Flight
Team member quits
1 4 1 Pre-Flight
Unmet external deadlines
2 5 3 Pre-Flight
Over budget 2 2 4 Pre-FlightIncrease in price of components
2 2 3 Pre-Flight
Risk ManagementProgram coding loss
1 4 2 Calibration
Memory deficiency
4 4 3 Flight
Unexpected environmental conditions
2 3 1 Flight
Battery malfunction
4 4 2 Flight
Payload breaks during construction
3 4 3 Pre-Flight
Data storage exceeds maximum memory space
4 4 3 Flight
Payload walls fall off during flight
1 5 4 Flight