Mission Statement and Objectives

Design Requirements

Functional• Log radiation and corresponding altitude for duration of flight

(up to 90,000 feet and back)• Store data on non-volatile memory• Provide power for duration of flight plus one hour set up and

one hour for recovery (4 hours minimum)• Indicate the unit is powered on• Indicate system is running properly • Ensure system is both water-resistant and buoyant• Provide internal fire resistance • Provide internal temperature regulation• Ensure system will operate within temperature range and

withstand forces of launch, ascent, balloon breaking, descent, and landing

• Ensure system can attach to research computer payload• Ensure combined system can attach to Borealis balloon Performance • Log radiation and altitude data each second • Provide 5 watts per hour over 4 hour flight• Provide sound and/or light to indicate power is on• Provide sound and/or light to indicate the system is operating

properly

• Ensure water cannot leak into system and payload floats• Enable system to shut down if internal temperature exceeds

100 C• Ensure system can withstand vertical force of 10Gs and

horizontal force of 5Gs (according to HASP requirements)• Ensure payload temperature stays within and will operate

between -60 and 60C (external) and between -20 and 40C (internal)

• Ensure pressure sensor can withstand 0-90kPa Physical• Ensure system does not exceed maximum dimensions: 5.5” by

5.5” by 5.5”• Ensure system does not exceed maximum mass: 6 lbs Reliability • Ensure system can launch twice and withstand internal tests:

• Drop test• Bench-top burn test• Cold room test• Water resistance test• Pressure test

• Recover all components and ensure internal components are not damaged

6

Choosing a PrototypeQuality/ Test Weight

Prototype 1 Prototype 2 Prototype 3 Prototype 4

Score Total Score Total Score Total Score Total

Temperature Gradient After 60 minutes

5 4 20 5 25 0 0 5 25

Burn Test 5 5 25 4 20 5 25 3 15Mass 5 4 20 5 25 3 15 5 25Temperature Loss After 60 minutes

5 5 25 2 10 4 20 5 25

Accelerometer 5 4 20 1 5 4 20 3 15Float Test 5 5 25 4 20 3 15 4 20

Total 135 Total 105 Total 95 Total 125

Picking Rigid Foam Board MaterialQuality/ Test Weight

Polyiso PolystyreneScore Total Score Total

Drill Test (with packing tape)

5 *5 25 2 10

Burn Test 5 5 25 5 25Mass 5 3 15 4 20

Temperature Gradient After 60 minutes

5 4 20 4 20

Temperature Loss After 60 minutes

5 4 20 5 25

Accelerometer 5 3 15 4 20Float Test 5 5 25 5 25 Total 145 Total 145

*Use Polyiso bottom to comply with attaching to other payload (better drilling score)

Final Prototype

-Hard Foam-Gorilla Tape

-Packing Tape

-Fiberglass

•Structural Material• Hard Foam

• Sides and Lid are polystyrene foam board• Bottom is made of polyiso foam board

Assembly•Method of Securing Electronics• ESD bag• Thinsulate bag• Packed in with shredded foam

•Method of Attaching Lid• Webbing with snaps

•Method of attaching to research computer payload• Bolts through our bottom into the top

of the other payload•Both payloads are then placed in a Nylon bag

CAD Video of Assembly

SpecificationsEnclosure Attachment Impact Forces/Environmental Protection

Specifications Pass? Specifications Pass? Specifications Pass?

6" cube check Attach to Research computer payload check Meets HASP requirements for G-

forces* check

Fits Electronics check Attach to BOREALIS check Buoyant &Water Resistant check

<1.0 kg check Electronics are secure check Lid is secure* check

Meets Internal Temperature Range* check

Electronics won't over heat * check

Testing

Tests to Check SpecificationsSpecifications Test

Meets HASP requirements for G-forces Accelerometer

Lid is secure Lid test with weight

Electronics won’t over heat Sun Test

Meets Internal Temperature Range Temperature Profile Test

Accelerometer Test Results•Three axis accelerometer with a lab view program• Converted voltages to G-Force

• ((V-2.7)/0.004)•Placed accelerometer inside the box (simulate what electronics feel)• Used a weight that had a mass of ~423 grams

• similar dimensions to electronics• Taped accelerometer to the weight

• Assembled as discussed above•Then placed the accelerometer on the outside of the box•Drop height of 3 meters

Accelerometer Test Results

17 1479 2941 4403 5865 7327 8789 10251117131317514637160990

100

200

300

400

500

600

700

800

900

Outside the Box

Sample Number

G-F

orce

12 1068 2124 3180 4236 5292 6348 7404 8460 9516 10572116280

50

100

150

200

250

300

Inside the Box

Sample Number

G-F

orce

•Max Resultant G-Force• ~788 G’s

•Max Resultant G-Force• ~276 G’s

Lid Test Results•Tied rope to bottom of box•Placed a weight inside• Used same weight as in accelerometer

test• Assembled as discussed before

•Swung box around in different directions•Had lid facing outward•Lid remained secure and didn’t move

Field Test Results•Calibrated thermocouples• Used: ice water, boiling water

•Used same heater as in cold tests• Assembled in manner described above

•Placed one thermocouple on the circuit board and one on the battery pack•Placed box in sun in 75⁰F weather • Measured temperature every 5 minutes• Stopped test when circuit board reached 60⁰C

• Test lasted75 minutes•Corrected the temperature readings using calibration curve•Graphed data (see next slide)

Thermocouple on circuit board

Thermocouple on battery pack

Field Test Results

0 10 20 30 40 50 60 70 800.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

Battery ThermocoupleCircuit Board Thermocouple

Time (min)

Corr

ecte

d Th

erm

ocou

ple

Tem

pera

ture

s (⁰C

)

•Assembled in manner described above•Placed one thermocouple on the circuit board and one on the battery pack•Placed in thermal oven• Took temperature measurements every 5 minutes• Followed the external temperature data from last years flight

•Corrected the temperature readings using calibration curve•Graphed data (see next slide)

Temperature Profile Test Results

Temperature Profile Test Results

0 20 40 60 80 100 120 140

-50.0

-40.0

-30.0

-20.0

-10.0

0.0

10.0

20.0

30.0

40.0

External Temperature

Battery Temperature

Circuit Board Temperature

Time (min)

Tem

pera

ture

(⁰C)

Mechanical Subsystem Bill of MaterialsBuilding Materials: $119.05packing tape, fiberglass kit,

gorilla tape, gorilla glue, nylon etc.

+Shredded Foam: $2.49+Polystyrene ½” Board: $2.45+Thinsulate: $14.99+TI Sensor Tag: $25

Total: $163.98

Schematic

Burn In Test

Burn In Test ResultsTime Voltage Battery Current Battery Voltage Converter Current Converter

5 min 8.900 0.1080 5.009 0.176

15 min 8.960 0.1080 5.009 0.175

30 min 8.990 0.1080 5.009 0.179

45 min 9.010 0.1086 5.009 0.177

60 min 9.015 0.1080 5.009 0.179

75 min 9.020 0.1073 5.009 0.180

90 min 9.022 0.1088 5.009 0.179

105 min 8.990 0.1087 5.009 0.176

120 min 9.000 0.1088 5.009 0.174

135 min 8.997 0.1087 5.009 0.180

150 min 8.960 0.1090 5.009 0.179

165 min 8.970 0.1094 5.009 0.175

180 min 8.974 0.1080 5.009 0.174

195 min 8.970 0.1090 5.009 0.177

210 min 8.971 0.1090 5.009 0.176

225 min 8.970 0.1077 5.009 0.175

240 min 8.970 0.1080 5.009 0.174

255 min 8.960 0.1090 5.009 0.177

270 min 8.966 0.1070 5.009 0.174

285 min 8.970 0.1084 5.009 0.175

300 min 8.970 0.1090 5.009 0.177

Static/ESD Bag Test

Due to the packaging method, static was a concern.

Using a oscilloscope the box was tested both with and without an ESD bag.

Conformal CoatingConformal coating was required due to both the geiger counter and the packing style of the payload.

Arathane (Uralane) 5750 Conformal Coating*Material Function Amount/10 Actual Amount

Uralane 5750 LV-A Curing Agent 0.54 g 0.84 g

Uralane 5750 LV-B Pre-polymer 3 g 4.47 g

Toluene (70 PBV) Diluent 2 g 2.96 g

* A similar product was used to stake the geiger counter

•Step 1: Cleaned boards• One bath Liquinox and DI water, followed by

two alcohol baths•Step 2: Dried boards• Placed in oven for approximately 45 minutes

•Step 3: Masked boards• All parts that could not be coated were

masked off•Step 4: Coating boards• Boards were coated with Arathane conformal

coating•Step 5: Dried boards• Boards were placed in oven for 14 hours at

50°C

Finished Payload

Geiger Counter: $149.95+Pressure Sensor: $45.44+DC/DC Converter: $19.97+Batteries: $69.70+Battery Packs: $4.98+PC Boards: $8.98+Thermal Cutoff: $8.91+USB Cables: $15.99+Misc: $2.80

Total: $326.72

Budget

0 4 8 12 16 20 24 28 32 36 40 44 48 52 56 60 64 68 72 76 80 84 88 92 96 100

104

108

112

116

120

124

128

132

136

140

144

148

0

100

200

300

400

500

600

-50

-40

-30

-20

-10

0

10

20

30

Radiation, Pressure, and External Temp vs Time

Radiation Counts (cpm)Pressure (psi)External Temp (⁰C)

Time (minutes)

Radi

ation

Cou

nts

(cpm

)

Pres

sure

and

Ext

erna

l Tem

p

0 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45 48 51 54 57 60 63 66 69 72 750

200

400

600

800

1000

1200

1400

1600

1800

0

2

4

6

8

10

12

14

Radiation and Pressure vs Time

Radiation Counts (cpm)Pressure (psi)

Time (minutes)

Radi

aito

n

Pres

sure

Budget

Raspberry Pi: $25+SD Card:

$13

Total:$38

Overall Budget

ME Materials $163.98+EE Materials $326.72+CS Materials $38.00

Total: $528.70

$71.30 under budget!!!

Thank You!