Speed of Sound

1. Speed of Sound Team BalloonWorks

2. 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

3. 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.

4. 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.

5. 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.

6. Science Background

7. Earth’s Atmosphere • Troposphere • Surface to ≈ 12 km • Temperature decreases • Stratosphere • ≈ 20 to 50 km • Temperature increases • Mesosphere • Thermosphere • Exosphere

8. 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.

9. Technical Background

10. 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

11. 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

12. 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

13. 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.

14. Payload Design

15. 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.

16. System Design

17. 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

18. Sensor Interfacing • Temperature Sensor: • Pressure Sensor:

19. Sensor Interfacing • RH Sensor:

20. Control Electronics

21. Power Supply

22. Power Budget

23. Power Budget

24. 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

25. Initialize all hardware pins and declare all variables Initiate EEPROM address to 0 Is EEPOM ADDR>=max EEPROM Address End Program Get RTC hour, minute, second values Write to EEPROM in increments of EEPROM Address Get ADC channel 0, 1, and 2 values Write to EEPROM in increments of EEPROM Address

26. 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

27. 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

28. Mechanical Design • Internal Design • Open Compartment • T, RH, Speaker, Recorder • Reflecting Arc • Closed Compartment • Pressure Sensor • Sensors’ Conditioning Circuitry • BalloonSat • Power Supply

29. Weight Budget

30. Payload Development Plan • Electrical Design Development • Software Design Development • Mechanical Design Development • Mission Development

31. Project Management Team Responsibility and contact information • Team Contract • Configuration Management Plan • Interface Control

32. WBS

33. Project Timeline and Milestones

34. Risk Management

35. Risk Management