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

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.

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.

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.

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

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.

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

Structural Tests Stair-Pitch Test Drop Test

Structural Tests Whip Tests

Electronics Board Mounting

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.

Cooler Testing

Cooler Test Results

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.

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.

Functional Block Diagram

Electrical Schematic

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

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

Setup

Results

Anemometer Testing

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

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.

Bench Test Results

Flight!

Flight Data Pre-launch Ascent Descent Burst

Pre-launch Ascent Descent Burst

Pre-launch Ascent Descent Burst

Pre-launch Ascent Descent Burst

Pre-launch Ascent Descent Burst

Pre-launch Ascent Descent Burst

Solar Power averaged over 10s

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

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

Questions? Tyler