1. CSU DemoSAT-B 2010 DemoSat V: Colorado State University April 9, 2011
Paul Scholz, Tyler Faucett, Abby Wilbourn, Michael Somers
April 9, 2011
This is Paul from CSU demosat-B and this is our PDR
Colorado State University

2. Mission Overview
Objective: to study alternative energy collection at different altitudes
Find the best possible altitude for alternative (wind & solar) energy collection.
Is high altitude energy collection worthwhile?
Can the added cost of high altitude energy collection be made up for with increases in efficiency?
Paul - The objective of our study is to find the ideal altitude for wind and solar energy collection. The data we collect could help a company determine if the added cost of high altitude energy collection, can be overcome by increases in efficiency.

3. How we can help
An airborne solar/wind power farm could be very useful for remote area power generation.
This payload is an affordable, reusable, lightweight way for anyone who want quick access to data to find the optimum altitude for renewable energy collection, as well as general atmospheric conditions at these altitudes.
Our test vehicle will provide data to give an altitude of maximum power generation.
Paul - After the launch day, we hope to use our data to be able to provide an altitude of maximum energy collection for both solar power and wind energy, as well as a combination of the two. This data could be very helpful to anyone trying to perform airborne alternative energy collection, whether it be in a remote location somewhere here on earth, or even on Mars where efficient power generation is needed.

4. Mission Requirements REQUIREMENT METH OD STATUS
Payload mass must be 1.5 kg or less
Design and use of lightweight materials
Payload must accommodate flight string per the users guide
Design and test
Payload must pass all structural tests in users guide
Payload must successfully complete all functional and environmental tests
Payload must have the capability to complete all mission objectives
Payload must cost under $1000
Budget carefully
Michael- Our top priorities are to measure wind speed and solar panel power. We have added in other sensors to gather an increase in accuracy in our two primary measurements. With temperature and pressure the altitude of the balloon can be found, as well as the air density. This is important because air density plays a large role in the amount of power that can be produced from wind. We will use an accelerometer to know the speed of the balloon. With this data the total wind speed will be known and not just the speed relative to the balloon.

5. Concept of Operations
Just before launch power to the resistor heaters and the AVR board will be turned on via a DPDT switch on the top of the payload
To initiate data collection, a launch button on the top of the payload must be pressed
The AVR microcontroller will run its program which includes taking input from 8 different sources and transmit the data serially back to flash memory at a rate of 2 Hz
Data will be collected until flash memory is full, lasting roughly 4.5 hours

6. Structural Design Must have cylindrical shape
Allows for even and constant sun exposure to solar faces
Must have center core flight string pass through
Pass through design must comply with all DemoSAT-B regulations
Must protect electronics from high forces and shocks
Must successfully complete all structural tests as specified in the DemoSAT-B regulations
Must measure wind speed outside the boundary layer caused by the payload
Michael- The first subsystem were looking at is structural. We designed the overall structure to have a cylindrical shape, so that the total sun exposure on the panels is equal regardless of the orientation of the payload on the string. We designed for a center string pass through which complies with all of the demosat-b criteria. Lastly we hope to keep the pressure difference from inside to outside the payload under 10 psi.

7. Max probable BL thickness-1.3 in
Tyler
Anemometer Height-5 in
Max probable BL thickness-1.3 in

9. Structural Tests
Stair-Pitch Test
Drop Test

10. Structural Tests
Whip Tests

11. Electronics Board Mounting

12. Thermal Design
The internals of the payload must remain above -10C to prevent failures of electrical components
5W 3.9 Ohm ceramic resistor heaters will be powered by two 9V batteries to maintain required internal temps
Resistors for solar panel circuit will also aid in heating the interior of the payload
Batteries will be placed as close to heat sources as possible
Internals of the payload will be fully insulated from the outside with 1.5 in thick Owens Corning insulation
Michael-Most of the payload structure is made from foam board insulation that is at least one inch thick in all areas and 1 ¾ in most. From our models we know that the center of the payload will most likely be the warmest area, so we hope to keep most of our critical components there. We have also purchased flexible heaters that can be used to heat certain components as well as the inside cavity of the payload.

13. Cooler Testing

14. Cooler Test Results

15. Electrical Design Circuitry Processing
All sensor data shall be processed using a modified version of the RockOn! AVR board
Solar panels, internal temperature sensor, external thermistor, pressure sensor, and accelerometers are connected to the AVR via A/D converters. The anemometer is read by pulse counting.
Storage
The flash memory must allow for computer interface
Must have enough storage space to last the entire flight
Programming must be written so that once flash memory is full, no data is overwritten
Circuitry
Circuits should consume as little power as possible… <.001W per sensor circuit
Michael-All of our measurement sensors are going to be attached to a PIC16F884 microcontroller. The data gathered from the sensors will be processed using the microcontroller, and the data will be sent to and recorded by external data storage unit every five seconds. In order to retrieve our launch data most easily, we decided on using an external SD card reader. That way we have a removable card that attaches easily to a computer interface.

16. Electrical Design Power
AVR board will be powered by a 9V lithium battery run through a 5V regulator
Heaters will be powered with two separate 9V lithium batteries connected in parallel for extended life
Michael-The PIC16F884 microcontroller that we are using can only be powered by a 5V source, otherwise we will fry the microcontroller and lose our data. All sensors and electrical components will be wired in a fashion that each can run on 5V. Also, the solar panels and wind anemometer will be producing a voltage that must be stepped down to 5V before the data enters the microcontroller to be processed. The power supply we use must be able to produce 4.8 to 6V for at least 2 hours to ensure each component receives the required voltage to operate for the entire flight period.
The switches will be mounted externally on the payload, one for all sensors and the PIC, and a separate one for the heaters (also a separate power supply). This complies with the Demosat-B guidelines for quick activation immediately before launch.

17. Functional Block Diagram

18. Electrical Schematic

19. Functional/Sensor Testing
Solar Panel Cold Test
Anemometer Testing
Bench Test

20. Solar Panel Cold Test
The solar panel output will be tested for variations in temperature
The panel, a 90 W light source above the panel, and a thermocouple will be placed inside a refrigerator originally at room temperature
The refrigerator will then be turned on to its highest setting
The solar panel output will be recorded at a constant temperature interval of 2 degrees Celsius

21. Setup

22. Results

23. Anemometer Testing

24. Anemometer Testing
(# of pulses * 2 * 2.5)= wind speed in mph

25. Bench Test Results
Paul – The possible point of failure on our functional test is mainly electrical. It is possible that we may see overheating of the internal electrical components. It is also possible that we don’t see any data transfer onto the SD card or even any communication between the microcontroller and the sensors. We plan on getting all of these tests done very early on so we have time to make any necessary changes in our electrical design or programming.

26. Bench Test Results

27. Flight!

30. Flight Data
Pre-launch
Ascent
Descent
Burst

31. Pre-launch
Ascent
Descent
Burst

32. Pre-launch
Ascent
Descent
Burst

33. Pre-launch
Ascent
Descent
Burst

34. Pre-launch
Ascent
Descent
Burst

35. Pre-launch
Ascent
Descent
Burst

36. Solar Power averaged over 10s

37. Conclusions: Wind Speed: Solar Collection:
High altitude does not guarantee high wind collection
This could be due to reduced air density at increased altitude
Optimum Altitude: Ground level
Solar Collection:
Above 25000ft in altitude we observed roughly constant solar power collection
Optimum Altitude: 25000ft

38. Lessons Learned: Design for structural and thermal issues
Start designing circuits early they take the most time
Start programming early
Order long lead time parts first
Use companies with quality customer service

39. Questions?
Tyler