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 Prototype
Quality/ Test
Temperature
Gradient After 60
minutes
Burn Test
Mass
Temperature Loss
After 60 minutes
Accelerometer
Float Test
Weight
Prototype 1
Prototype 2
Prototype 3
Prototype 4
Score
Total
Score
Total
Score
Total
Score
Total
5
4
20
5
25
0
0
5
25
5
5
5
4
25
20
4
5
20
25
5
3
25
15
3
5
15
25
5
5
25
2
10
4
20
5
25
5
5
4
5
20
25
1
4
5
20
4
3
20
15
3
4
15
20
Total
135
Total
105
Total
95
Total
125
Picking Rigid Foam Board Material
Quality/ Test
Drill Test (with
packing tape)
Burn Test
Mass
Temperature
Gradient After 60
minutes
Temperature Loss
After 60 minutes
Accelerometer
Float Test
Weight
Polyiso
Score
Total
Polystyrene
Score
Total
5
*5
25
2
10
5
5
5
3
25
15
5
4
25
20
5
4
20
4
20
5
4
20
5
25
5
5
3
5
Total
15
25
145
4
5
Total
20
25
145
*Use Polyiso bottom to comply with attaching to other payload (better drilling score)
Final Prototype
•Structural Material
•Hard Foam
•Sides and Lid are polystyrene foam board
•Bottom is made of polyiso foam board
-Hard Foam
-Gorilla Tape
-Packing Tape
-Fiberglass
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
Specifications
Enclosure
Attachment
Impact Forces/Environmental Protection
Specifications
Pass?
Specifications
Pass?
Specifications
Pass?
6" cube
check
Attach to Research computer
payload
check
Meets HASP requirements for Gforces*
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 Specifications
Specifications
Test
Meets HASP requirements for Gforces
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
600
500
400
G-Force
Outside the Box
900
800
300
200
0
Sample Number
•Max Resultant G-Force
• ~788 G’s
1
501
1001
1501
2001
2501
3001
3501
4001
4501
5001
5501
6001
6501
7001
7501
8001
8501
9001
9501
10001
10501
11001
11501
1
681
1361
2041
2721
3401
4081
4761
5441
6121
6801
7481
8161
8841
9521
10201
10881
11561
12241
12921
13601
14281
14961
15641
16321
G-Force
Accelerometer Test Results
Inside the Box
300
700
250
200
150
100
100
50
0
Sample Number
•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
Corrected Thermocouple Temperatures (⁰C)
70.0
60.0
50.0
40.0
Battery Thermocouple
Circuit Board Thermocouple
30.0
20.0
10.0
0.0
0
10
20
30
40
Time (min)
50
60
70
80
Temperature Profile Test Results
•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
40.0
30.0
20.0
Temperature (⁰C)
10.0
External Temperature
0.0
0
20
40
60
80
120
140
Battery Temperature
Circuit Board Temperature
-10.0
-20.0
-30.0
-40.0
-50.0
100
Time (min)
Mechanical Subsystem Bill of Materials
Building Materials:
$119.05
packing tape, fiberglass kit,
gorilla tape, gorilla glue, nylon etc.
+
Shredded Foam:
+
Polystyrene ½” Board:
+
Thinsulate:
+
TI Sensor Tag:
Total:
$2.49
$2.45
$14.99
$25
$163.98
Schematic
Burn In Test
Burn In Test Results
Time
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 Coating
Conformal coating was required due to both the
geiger counter and the packing style of the payload.
•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
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
3g
4.47 g
Toluene (70 PBV)
Diluent
2g
2.96 g
* A similar product was used to stake the geiger counter
Finished Payload
Budget
Geiger Counter:
+
Pressure Sensor:
+
DC/DC Converter:
+
Batteries:
+
Battery Packs:
+
PC Boards:
+
Thermal Cutoff:
+
USB Cables:
+
Misc:
$149.95
Total:
$326.72
$45.44
$19.97
$69.70
$4.98
$8.98
$8.91
$15.99
$2.80
Radiation, Pressure, and External Temp vs Time
600
30
20
500
0
300
-10
-20
200
-30
100
-40
0
-50
Time (minutes)
Pressure and External Temp
400
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
105
110
115
120
125
130
135
140
145
Radiation Counts (cpm)
10
Radiation Counts (cpm)
Pressure (psi)
External Temp (⁰C)
Radiation and Pressure vs Time
1800
14
1600
12
1400
10
8
1000
800
6
600
4
400
2
200
0
0
0
5
10
15
20
25
30
35
40
45
Time (minutes)
50
55
60
65
70
75
Pressure
Radiaiton
1200
Radiation Counts (cpm)
Pressure (psi)
Budget
Raspberry Pi:
+
SD Card:
$25
Total:
$38
$13
Overall Budget
ME Materials
+
EE Materials
+
CS Materials
$163.98
Total:
$528.70
$326.72
$38.00
$71.30 under budget!!!
Thank You!