Team Ram-Rod. Rod. Aaron Gardiner Tyler Murphy Vivian Phinney Farheen Rizvi Ali Toltz

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2 Team Ram-Rod Rod Aaron Gardiner Tyler Murphy Vivian Phinney Farheen Rizvi Ali Toltz May 2 nd, 2006

3 Mission Overview Helios intends to test the effectiveness of two different brands of sunscreen (SPF 30) when exposed to ultraviolet radiation Helios will use pressure data from a barometric switch to determine satellite s ascent and descent rates Helios will take photographs of the Earth during flight

4 RFP Compliance Mass 745 g < 775 g Obtain Internal/External Temp Internal dropped below 0 C 0 Acquire Ascent/Descent Rates 15 ft/s Imaging Picture of Earth Have fun check

5 Design Overview

6 Sunscreen Experiment Concept Sunlight falls on fused silica and sunscreen system Absorption occurs Light falls on UG11 UV filter Photons from the filtered light are detected by photodiodes Photodiode produces varying current proportional to the amount of photons detected Varying current in amplifier circuit produces varying DC voltage output Voltage data stored in HOBO data loggers Voltage data is converted to light intensity (Watts) Experiment Concept Model

7 Amplifier Circuit Diagram

8 Rotating disk: Rotating Motor Low speed and high torque Two brands of sunscreen Neutrogena and Kroger Sunscreen Experiment Design Red leak OG515 filter Only allows red leak to pass Subtract its affect from results Black (brass) No UV passes through Indicator of one complete rotation of wheel Blank (fused silica) All light should pass through Accounts for any light absorption by fused silica Rotating Disk Model

9 Barometric Switch Experiment Measures atmospheric pressure Mechanism Bellow expands as pressure changes Wiper arm moves as change in pressure expands the bellow The wiper arm hits contacts which are laid out in a serpentine pattern Wiper OFF contact open circuit 0 V Wiper ON contact complete circuit voltage output Each contact corresponds to an air pressure

10 Summary of Flight Launch site Windsor, CO Launch successful spin at beginning due to late release Reached maximum altitude - 99,487.9 ft Landing site South East of Keota, CO Flight duration 2:13:19 Avg. Ascent/Descent rates ft/s

11 Results and Analysis: Barometric Switch Combine pressure data from barometric switch and hydrostatic equation to determine ascent/descent rates Hydrostatic equation Avg. Ascent/descent rate:15.00 ft/s dz dp dz dp dz dt RT gp dp RT dp dt gp dt RT avg P 2 P 1 gp avg t Avg. Actual rate (EOSS): ft/s Z: altitude (m) R: gas constant (J/K*kg) T avg : average temperature (K) g: acceleration due to gravity (m/s 2 ) P avg : average pressure (Pa) t: time (seconds)

12 Results and Analysis: Sunscreen Experiment Plot illustrates absorption of light by different filters Light intensity data obtained through voltage data Light intensity at 10:17 AM is greater than light intensity at 8:16 AM Neutrogena (expensive) sunscreen proves to be better than Kroger sunscreen

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14 Predicted vs. Actual Barometric Switch Expected Plot of logical highs and lows corresponding to changes in pressure Actual Plot was saturated produced desired results following longer data analysis than expected Temperature Expected Remain above 0 C 0 C for duration of flight Actual Dropped below freezing due to heater malfunction Reached minimum -50 C.

15 Wheel Data Predicted Predicted vs. Actual cont d Fused Silica > Kroger > Neutrogena > Red Leak > Brass Actual Camera As expected Effects of Red Leak not as significant as expected, but still higher than Brass Significant difference between performance of Neutrogena vs. Kroger brands Data pattern remained consistent Predicted Clear unobstructed shots on ascent and descent at three min. intervals Actual Obstructed shots only on ascent

16 Conclusions Mission produced expected results Sunscreen Neutrogena is 7 times more effective than Kroger Neutrogena costs 1.7 times more than Kroger Barometric Ascent/descent rate was 15 ft/s Camera Successful in taking pictures of the earth during ascent

17 System s s Failure Analysis Assembly failure Camera mounting position Design failure Heating system Camera failure Power 555 Timer Experiment motor failure Experiment power failure

18 Message to Next Semester Lessons Learned Finalize experiment design early Team communication is key Follow the KISS principle Leave enough time for testing Ensure everyone contributes to the project use everyone's skills

19 Appendix Filter selection UG11 OG515 Photodiode selection S blue enhanced photodiode Calculation for feedback resistor

20 UG11 Filter Selection UG11 Filter Wavelength of UV light: nm Allows Red Leak to pass through use another filter to discard its affect on the amount of light falling on the photodiode UG11 Filter Performance under Light Exposure 1 OG515 filter UG11 filter

21 S Photodiode Selection Performance of S Photodiode under light 1 S blue enhanced photodiode Range: 1.2 Amps/Watt 1.8 Amps/Watt

22 OG515 Filter: Red Leak Plot 4 presents the performance of the OG515 filter when exposed to light. Filter allows all wavelengths greater than 500 nm to pass through blocks UV subtract affects of light on the photodiodes other than those of UV Plot 4: OG515 red leak filter performance under light 1

23 Feedback Resistor Determine from plot 1 wavelength at maximum filter transmission (320 nm, 80%) Full Width Half Maximum (FWHM) of UG11 filter Determine from plot 2 Irradiance (watts/m 2 nm) Consider 80% Irradiance reaching photodiode due to absorption by UG11 filter Not looking at direct sun Irradiance intensity is 100 times less Actual Irradiance = 0.008*Irradiance Plot 1: UG11 filter performance under exposure Plot 2: Solar Irradiance 1

24 Feedback Resistor Contd. Determine area of photodiode (4.1 mm diameter) Calculate number of watt falling on the photodiodes from area and FWHM Compute amount of current produced per watt from plot 3 Calculate the value of resistor (in Ω) ) from V = IR Plot 3: S Photodiode Performance under light

25 Thank you! Any questions?