Gateway to Space ASEN
1400/ASTR 2500
1
Colorado Space Grant Consortium
ASEN 1400 & ASTR 2500 Gateway to Space
Fall 2012
PROJECT(BOOM)2
DESIGN DOCUMENT D
Team Apollo 18
Maggie Williams
Peter Merrick
Lindsey Buxman
Nathan Buzzell
Jared Levin
Cody Gondek
Chris Davidoff
Jacob Hermann
Fall 2012
GATEWAY TO SPACE ASEN 1400/ASTR 2500
Revision Log
Revision
A/B
C
D
Description
Conceptual and Preliminary
Design Review
Critical Design Review
Analysis and Final Report
Date
10/22/12
11/16/12
12/13/12
Table of Contents
1.0 Mission Overview................................................................................................................2
2.0 Requirements Flow Down....................................................................................................4
3.0 Design...................................................................................................................................6
4.0 Management ........................................................................................................................12
5.0 Budget..................................................................................................................................13
6.0 Test Plan and Results...........................................................................................................15
7.0 Expected Results..................................................................................................................21
8.0 Launch and Recovery…………………………………………………………………........23
9.0 Analysis and Results………………………………………………………………………...24
10.0 Ready for Flight…………………………………………………………………………….29
11.0 Conclusion and Lessons Learned…………………………………………………………..29
12.0 Messages to Next Semester………………………………………………………………...30
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1.0 Mission Overview
1.1 Mission Statement
Team Apollo 18 shall conduct an experiment to calculate the speed of sound as the balloon rises
to a height of 30 kilometers. The satellite will calculate the speed of sound waves traveling from
one box to the other 1.364 meters away. Since pressure and temperature affect the speed of
sound, the data collected will be compared to changes in pressure and temperature and prove or
disprove this relationship.
The speed of an object is the ratio of the distance traveled over the time elapsed. This ratio can
be expressed in many ways including the following: miles per hour, meters per second, and feet
per minute. In this experiment Apollo 18 used the ratio of meters per second.
The speed of sound is affected by two different properties of the medium (solid, liquid, or gas)
the sound wave is traveling through – elastic properties and inertial properties. The elastic
property of the medium explains how the particles in the medium react to an outside force. If the
particles are rigid and maintain their shape, the substance is considered to have a high elasticity;
if the particles move drastically from their original positions and their arrangement becomes
deformed, the substance has a low elasticity. Since the particles in solids are closer together than
those in gasses, sound tends to travel faster in solids than in gases. The inertial property of the
substance also influences the speed of sound. When moving through a single medium, the
inertial property has the greatest influence on the speed of sound. The inertial property takes into
consideration the density of the particles in the medium. The air is made up of many different gas
molecules with varying densities. As sound travels through highly dense air molecules, its speed
will decrease due to more resistance; as sound travels through less dense air molecules, its speed
will increase due to less resistance.1 Temperature also affects the speed of sound; sound travels
faster at higher temperatures than at lower temperatures. An equation that could calculate the
speed of sound in air is v = 331.4 + 0.6Tc in m/s where v is the velocity and Tc is the temperature
in degrees Celsius .2 This equation will be the standard that the results can be compared against.
1.2 Mission Objectives

Test how sound travels at an altitude of 30 km

Experimentally calculate the speed of sound

Determine how much temperature and air pressure affect the speed of sound
Apollo 18 shall use the data that obtained from the Arduino to calculate the speed of sound, and
then we shall use the temperature data obtained and put it into the equation v = 331.4 + 0.6Tc
m/s. We will then compare the experimental and calculated speed of sound.
This data can be useful for future space missions because scientists can determine the density of
the atmosphere for other planets based on the rate of change of the speed of sound. If scientists
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know how dense the planet’s atmosphere is, they can make calculated guesses at what gasses
compose that atmosphere and how abundant those gases are.3
1
"The Speed of Sound." The Speed of Sound. The Physics Classroom, n.d. Web. 14 Oct. 2012.
<http://www.physicsclassroom.com/class/sound/u11l2c.cfm>.
2
"Speed of Sound in a Gas, Sound." Speed of Sound in a Gas, Sound. Electronics Teacher, n.d. Web. 14 Oct. 2012.
<http://www.electronicsteacher.com/succeed-in-physical-science/sound/speed-of-sound-in-a-gas.php>.
3
"The Speed of Sound in Other Materials." The Speed of Sound in Other Materials. NDT Education Resource
Center, n.d. Web. 14 Nov. 2012. <http://www.ndt-ed.org/EducationResources/HighSchool/Sound/speedinmaterials.htm>.
2.0 Requirements Flow-Down
Level 0 Requirements
#
Requirement
0.0 Test the speed of sound in relation to altitude
0.1 Experimentally calculate the speed of sound
0.2
0.3
0.4
0.5
0.6
Reach an altitude of 30km
Keep internal temperature above -10°C
Do not exceed either $250 or 1125g
Run a camera and an Arduino with other experiments
Safety and testing
Origin
Mission
Statement
Mission
Statement
Mission
Statement
RFP
RFP
RFP
RFP
Level 1 Requirements
Requirement 0.0: Test the speed of
sound in relation to altitude
#
Requirement
0.0.0
Stabilize a distance between speakers and a microphone
0.0.1
Speakers send out a sound picked up by the microphone
A stopwatch controlled by an Arduino Uno measures the time from the speakers to the
0.0.2
microphone
0.0.3
The data of the speed of sound is recorded with an Arduino Uno
0.0.4
Recover data after flight for further calculations
Requirement 0.1: Experimentally
calculate the speed of sound.
#
0.1.0
Record speed of sound during flight
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Origin
0.0
0.0
0.0
0.0
0.0
Requirement
Origin
0.1
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Record temperature during flight
Compare calculated speed of sound by temperature with experimental speed
0.1
0.1
Requirement 0.2: Reach an
altitude of 30km
#
Requirement
0.2.0
Attach our BalloonSat to a hydrogen balloon
0.2.1
A flight string will pass through our structure held together by washers and a paperclip
Origin
0.2
0.2
Requirement 0.3: Keep internal
temperature above -10°C
#
Requirement
0.3.0
Two heaters will be attached to a total of 4 9v batteries
0.3.1
The BalloonSat will be insulated with foam core and sealed with aluminum tape
0.3.2
Administer a dry Ice test to make sure it properly functions
Origin
0.3
0.3
0.3
Requirement 0.4: Do not exceed
either $250 or 1125g
#
Requirement
0.4.0
Record an accurate table of our budget including weight
0.4.1
Refer to budget before making changes to weight or buying materials
Origin
0.4
0.4
Requirement 0.5: Run a camera
and an Arduino with other
experiments
#
Requirement
A Canon SD780 IS 18x55x88mm and 130 grams will be used to take pictures of Earth
and/or the Sun.
0.5.0
0.5.1
The camera will take pictures every 10 seconds
0.5.2
An SD card inside the camera will save the images
0.5.3
Measure internal and external temperature with an Arduino Uno
0.5.4
Measure pressure with an Arduino Uno
0.5.5
Measure humidity with an Arduino Uno
0.5.6
Measure velocity with an accelerometer with an Arduino Uno
0.5.7
Recover and analyze data and photos
Origin
0.5
0.5
0.5
0.5
0.5
0.5
Requirement 0.6: Safety & Testing
#
Requirement
0.6.0
Maintain distance and practice safety while building and testing the BalloonSat
0.6.1
Use dry ice test to emulate near space temperatures
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Origin
0.6
0.6
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0.6.2
0.6.3
0.6.4
0.6.5
0.6.6
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GATEWAY TO SPACE ASEN 1400/ASTR 2500
Test speakers and microphone to ensure they are properly working
Administer whip and drop tests to ensure the strength will hold in near space conditions
Test Arduino Uno to ensure proper data recording
Test camera to ensure good pictures
Place lights on exterior to show the systems are on
Place contact information and U.S. flag on exterior in case someone else recovers the satellite
0.6
0.6
0.6
0.6
0.6
0.6
3.0 Design
3.1 Structural Design
The structure is made of two separate balloon satellites connected by two, two meter long,
carbon fiber tubes. To attach these tubes, they will be placed through the box equidistant from
the center and two corners. They will go through both boxes, and on the top of the top box and
the bottom of the bottom box, super glue will be used to attach pieces of plastic to where the
tubes come out of the box. This will prevent the tubes from tearing through the top of the box
upon impact. The area where the tube goes into the box on the bottom of the top box and the top
of the bottom box will additionally be glued to ensure it does not slip.
The Bottom Box has dimensions of 180 x 180 x 140 mm, and will contain the majority of the
equipment. This equipment includes the Canon camera, two Arduinos with relevant shields, and
most of the environmental sensors. These sensors are: the accelerometer, internal temperature,
external temperature, pressure sensor, and humidity sensor. Other equipment in the Bottom Box
will include a heater with switch and batteries and our microphone. One Arduino encompasses
the environmental sensors, and the other controls the microphone and collects data from the
speakers for our experiment. The Top Box, with dimensions of 180 x 180 x 60 mm, has another
heater with a switch and batteries, and also four speakers.
These boxes will be assembled using hot glue and reinforced with aluminum tape. Holes will be
cut in the center of both boxes so that tubing may be placed and the cord may run through. The
tubing will be secured by washers. Other modification to the box will include a hole 5.08 x 5.08
cm the side of the boxes so that the camera may take pictures, and three small pin holes in the
top boxes for wire to run through to collect external temperatures. All of the equipment will be
fixed to the sides or bottom using Velcro. This design will be test using the test procedure listed
later and maybe modified based on the results.
3.2 Experimental Design
The goal of the satellite is to test the speed of sound as altitude increases, temperature varies, and
pressure is lowered. Those environmental factors are collected by an Arduino located in the
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Bottom Box. They are programmed to collect the data every second and to store it into an SD
card. The speed of sound is found using an electronic stopwatch programmed into the Arduino
which records the time between the speaker releasing the sound and the microphone receiving it
in microseconds. That, and the fixed distance of 1.364 meters between the two boxes, will give
us the speed of sound.
The experiment is set up so that every 1 second the Arduino in the Bottom box will start an
electronic stopwatch and trigger the speaker to send out a ton at a frequency of 3600HZ. Once
the sound is received by the microphone on the top edge of the Bottom Box, the Arduino will
stop the stopwatch and give a total elapsed time in microseconds. This is made possible by the
wire running down the length of the tube, connecting the two boxes, and temperature does not
have an influence on this signal. That time is then converted into seconds. Then we can use the
equation: Speed = distance/time. The data is stored onto an SD card and the process is repeated.
Once the data is retrieved, we can compare the change in speed of sound against the change in
temperature and air pressure and compile the final results.
Adjustments
Data is filtered in two ways. The first is by setting a threshold. The Electret Microphone gives a
reading based on a combination of frequency and DB, with DB being the majority. To filter, the
threshold is set high enough that wind noise or any other noise won’t trigger the microphone.
Second, the data collected is filtered when the microphone does trigger. To compensate any
measurements below or above certain times are left out and not recorded on the SD card. The
average time is a little under 5 milliseconds so a reading of 2 seconds could through the data off.
To be able to collect data continuously, and for the sake of calibration, the Arduino must shut off
the tone after it hears it. So in the experiment, instead of one long beep, it really sounds like a lot
of little clicks. The Arduino auto-stops the tone after two seconds, and restarts the loop.
Originally, the satellite contained RF links to communicate between the two boxes almost
instantaneously, but upon further investigation, they proved to be unnecessary, and the design
changed to include a wire running down the poles to connect the speakers to the Arduino instead.
3.3 Hardware
Pressure sensor - Provided
The pressure sensor reads the average psi that our satellite is exposed too. The pressure sensor
has limitations at the top and bottom end of its range. It does not go below 0 psi, and it tops out
at 15 psi and. This is not likely to affect the experiment since we will not go above 14 psi or
reach a vacuum.
Temperature sensors - Provided
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The temperature sensor that is provided responds to change in the ambient temperature. It then
sends this to the Arduino and is stored on an SD card. There are very few limitations that go
along with the temperature sensor. It will gather all readings in any temperature range that are
needed.
Electret Microphone - SparkFun
The microphone detects the loudness of the surroundings and is then routed through an amplifier
to make it so the Arduino can read the results. Since there will be some random noise, the
readings will be filtered so that only a certain volume will trip the sensor. This means that it is
possible to get false results if the wind noise is too loud. This should not be an issue considering
the wind will have to be extremely massive, all at one time, and timed in the three millisecond
intervals, and our wind test resulted in no unusual errors. Constant wind will not cause enough
noise to trigger the sensor, only a massive gust will.
Speaker - Sparkfun and Digikey
Apollo 18 has acquired several different types of speakers: On 8 ohm diaphragm speaker that can
handle .2watts of power at max. It is rated at 80DB at .1m at .1 watt. When it is overclocked it is
louder. Several Pezios have also been acquired that vary in strength, max power output, and
voltage needed. They range from 75 to 85 DB at .1 M. Through testing, the best possible
combination proved to be two of each type of speaker.
Carbon Fiber – Good Winds
The carbon fiber is 4.57 mm in diameter (slightly less than the diameter of a pencil) and will
stretch 1.524 meters. Two poles will be used and they serve mainly to keep a rigid structure.
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3.4 Top Box
3.5 Bottom Box
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3.6 Side View
Note: The white tube down the middle represents the string; we will not have a tube running
down the distance between the boxes, only inside the boxes.
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3.8 Functional Block Diagram
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4.0 Management
4.1 Schedule
Team meetings shall be held every Monday from 7-9 PM. These meetings are not concrete
however, and may be rescheduled if the majority of the team has outside conflicts. Another
optional meeting time, if needed, is 7:30-9 PM on Thursdays.
9/20
9/24
9/28
10/1
10/2
10/5
10/8
10/15
10/18
10/18
10/22
10/29
11/1
11/3
11/5
11/8
11/10
11/11
11/12
11/15
11/16
11/26
11/27
11/30
12/1
12/3
12/6
12/8
12/10
12/11
12/13
Split up proposal work, HW #4
define mission, work on proposal
Proposal Due
work on presentation and HW #5
Presentations Due
ATP and Hardware Ordering
Design Document work
pCDR work and finish DD A/B
Build Satellite structure
Design Document AB and pCDR due
Drop Test and Whip Test- Individual boxes, HW 7
Attach carbon fiber tubes
Structural Testing Part I
Soldering, Structural Testing Part II
Building and insulation, hardware testing
Put hardware inside satellite
Finish structure
Dry Ice Test
Update DD C, hardware testing
In-Class simulation Test
Design Document C Due
Final fixes, make presentation
Launch Readiness Review
Final BalloonSat Weigh-in and Turn-in
Launch Day
Prepare for Design Expo, Data compiling
Team videos, data processing
Design Expo- Team Videos due
Presentation and design document work
Final Presentation and Reports- Turn in hardware
Design Document rev D due, Final class
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4.2 Team Organization
Our team is organized in the following manner, with each person holding two main titles and
communicating with every other team member. With documents and other reports, everything
goes through the team leader to uphold consistency.
Nathan Buzzell
Structural Engineer
Soldering Lead
Cody Gondek
Electrical Engineer
Testing Manager
Lindsey Buxman
Science Researcher
Editor
Jared Levin
Science Lead
Cinematographer
Maggie Williams
Team Leader
Scheduling Manager
Peter Merrick
Arduino Programmer
Diagram Manager
Chris Davidoff
Arduino Programmer
Electrical Engineer
Jacob Hermann
Financial Officer
Structural Engineer
5.0 Budget
The hardware will be carefully selected in order to assure that the group gets the best deal. This
way we will spend the least amount of our budget on the hardware that we need for the
satellite. The group was allocated a budget of $250. Apollo 18 will be able to purchase
everything needed with this budget. Also, the team has set aside an extra $90 just in case we
need to purchase any other supplies such as dry ice, batteries, or anything else. Jacob will be in
charge of the budget and will keep track of all of the group spending.
5.1 Item List
Item
Cost
Source
Mass
Arduino UNO (X2)
Provided
Gateway
30 (X2) g
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Proto Shield
Provided
Gateway
10 g
External Temperature Sensor
Provided
Gateway
2g
Internal Temperature Sensor
Provided
Gateway
2g
Canon SD780 IS
Provided
Gateway
130 g
Active Heater System
Provided
Gateway
100 g
Foam Core
Provided
Gateway
70 g
Contact Info/ US Flag
Provided
Gateway
5g
Flight String Interface Tube
(non-metal)
Braided Dacron Line
Provided
Gateway
10 g
Provided
Gateway
N/A
2 Eyebolts
Provided
Gateway
5g
2 Anti-Abrasion Bushings
Provided
Gateway
5g
Pressure Sensor
Provided
Gateway
5g
3 Axis Accelerometer
Provided
Gateway
5g
Humidity Sensor
Provided
Gateway
5g
Batteries (X7)
Provided
Gateway
45.6 (X7) g
Aluminum Tape
Provided
Gateway
5g
Velcro
Provided
Gateway
10 g
Insulation
Provided
Gateway
7g
Switches
Provided
Gateway
5 (X3) g
Hot Glue
Provided
Gateway
5g
Dry Ice
$20.70
King Soopers
N/A
Speakers Type 1
$4.12
Digi-Key
N/A
Speakers Type 1
$4.12 (X2)
Digi-Key
5 (X2) g
Speakers Type 2
$1.87
Digi-Key
N/A
Speakers Type 2
$1.87 (X2)
Digi-Key
5 (X2) g
Speakers Type 3
$1.03 (X3)
Digi-Key
N/A
Test Speaker (PCB Mount)
$1.95
SparkFun
N/A
Microphone
$7.95
SparkFun
7g
RF Transmitter
$3.95
SparkFun
N/A
RF Receiver
SparkFun
N/A
Heater System
$4.95 + 2.00
Handling
$9.99
SparkFun
50 g
Test Batteries
$12.98
Home Depot
N/A
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Hot Glue
$4.32
Michaels
N/A
Super Glue
$5.67
Home Depot
N/A
Small Metal Fasteners
$1.18
Home Depot
50 g
Carbon Fiber Tubes (X2)
$6.99 (X2)
Goodwinds
24gm (X2)
Fiberglass Tubes (X2)
$2.05 (X2)
Goodwinds
N/A
Total Cost
$121.78
1110 g
Note: The gray items were provided to us, the purple items are items we bought, and the red
items are items we bought that we’re not using on our final satellite.
6.0 Test Plan
6.1 Drop Test
In order to test whether the structure will survive the flight, the structure was dropped from both
the first floor and the second floor of the DLC lobby, in order to simulate the violent landing that
will occur. From both of these heights, the box survived with minimal damage when tossed at an
angle. The corners bent in slightly from the impact, but extra insulation will be applied to the
corners to make up for this possibility. It is only when the stacked boxes land completely
vertically on the bottom box that there is a structural problem, but any movement of the poles
upon landing will not affect any
of the hardware. This ensures
that Apollo 18 will be able to
safely retrieve the parts and
attain the logged data
6.2 Dry Ice Test
Apollo 18 tested the satellite’s
ability to last through the
extreme temperatures that it will
encounter through its ascent to
30 kilometers by placing it
inside large tub that contains some dry ice bought at the local King Soopers. Because the fully
constructed satellite would not fit in any box of dry ice, we tested with the boxes closer together,
but with everything besides the structure fully completed and operational. The subsystems ran
two hours, and all systems functioned properly for the duration of the test. There were just a few
concerns with the sensors, addressed below.
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millis (ms)
125472
250311
375123
499964
624782
749575
874259
999273
1124063
1248917
1373773
1498504
1623481
1748198
1873115
1997769
2122712
2247502
2372146
2497197
2621905
2746859
An external
Box in dry ice
35
temperature
Temperature (degrees C)
sensor was
30
connected to the
25
Arduino and
20
wired to the
outside of the
15
Internal Temp (Deg C)
box.
10
External Temp(Deg C)
Unfortunately
5
the temperature
sensor was too
0
close to the box
and also
insulated by
plenty of hot
glue, therefore it incorrectly recorded the temperature outside of the box. In order to fix this the
temperature sensor was extended farther away from the box. Apollo 18 will now conduct a test
placing the box outside with the heaters on, verifying that the outside temperature does decrease
as the satellite remains warm.
An internal temperature sensor was connected to an Arduino and recorded the temperature inside
of the box during the dry ice test. This data would be used in order to prove whether or not the
heaters inside the box
1.5
would be sufficient
enough to protect our
electrical components
1
Box in dry ice
from the harsh
environment that the
0.5
box will encounter on
AccelX (g)
its way to the edge of
AccelY (g)
0
Earth’s atmosphere.
AccelZ (g)
The graph shows that
-0.5
the temperature inside
of the box rose to
Adjustments
around thirty degrees
-1
Celsius, proving the
millis
624782 1248917 1873115 2497197
(ms)
health of the heating
systems.
Accelerometer readings (g's)
The accelerometer’s readings are consistent with the movements the satellite made during the
dry ice test. There are a few spikes when the boxes were checked up on and the code was
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adjusted, but besides this the measurements are normal. The directions will need now be
calibrated and zeroed at the right values now that the sensor and Arduino are inside the box.
Humidity (%)
25
20
Box in dry ice
15
Box out of
dry ice
10
Humidity (%)
5
millis (ms)
156024
311538
466924
622295
777635
933209
1088403
1243925
1399340
1554758
1710160
1865639
2020954
2176309
2331644
2487220
2642476
0
Pressure (psi)
14
12
10
8
6
4
2
0
Pressure (psi)
millis (ms)
215266
430007
644729
859296
1074068
1288840
1503492
1718270
1932944
2147647
2362181
2577015
A pressure sensor is connected to the
Arduino in the bottom box and will
record the pressure throughout the
launch. Since the dry ice test occurred
on the ground, the pressure relatively
stayed the same. As the box ascends
the expectation is to see the pressure
decrease.
A humidity sensor is
used in order to
record the amount of
water vapor in the
air. The humidity
sensor ran during the
dry ice test and
recorded the data as
a percentage. The
graph shows a line of
decreasing humidity
percentage as the test
was carried out.
The experimental data collected
during the dry ice test proved that the
sensor continues to function even in
cold conditions. The jump in time elapsed halfway through the test indicates when the satellite
was briefly taken out of the dry ice box to adjust the code that controlled the volume of the tones
being sent out by the speakers and the length of time the tone will continue if an error is made
and the microphone does not pick up the sound and thus stop the sound. It was discovered that as
the batteries run low, the readings of the microphone are less and less accurate, so this will need
to be looked out for during the flight.
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Dry Ice Test- .1 meters apart
500
450
400
350
300
250
Time Elapsed (micro)
200
150
100
50
0
0
1
2
3
4
5
6
Thousands (ms)
6.3 Whip test
The whip test was conducted by attaching a rope to the middle
of the foam core and swinging it around to mock the possible
gravitational forces that the satellite will have to endure
throughout its journey.
A rope was run through both of our boxes in a way similar to that
of the actual flight attachment. The apparatus was then spun
vigorously. No part of the satellite structure was damaged. The
carbon fiber tubes are very strong, yet allow for some bending
while spinning, so that the structure doesn’t fail.
6.4 Kick Test
In this test, the satellite was kicked down the stairs in the DLC
lobby to prove that it will survive any tumbling on hard surfaces
as if falls back to the ground.
The satellite did not suffer any damages during this test and
proved that it can sustain harsh falls back to Earth. The carbon
fiber poles held up very well to the testing and did not show any
signs of weakness. When the satellite is attached to a string tied
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with knots on both ends, the likelihood of the distance between the boxes changing and the
likeliness of the structure being compromised is very low.
Experiment Test- .65 meters apart
Thousands (microseconds)
6.5 Calibration/
Experiment Test
10
9
8
7
6
5
4
3
2
1
0
Because the experiment
depends on the precision
of the satellites ability to
record elapsed time, a
Time Elapsed
time test was conducted
to determine the speed
of sound on the ground,
where the speed is
0
20
40
60
80
known. The sensors
Thousands (ms)
were calibrated so that
the time elapsed when the boxes are touching is zero. With these different measurements it was
possible to find the speed of sound at this smaller distance in order to calculate our percent error.
Because the Arduino can track time in microseconds, it will be possible to calculate the change
in the speed of sound just from distancing the two boxes by 1.364 meters. However, the
calculated percent error shows that it is possible to collect valid data with less distance than
1.364 meters.
Using the time elapsed,
averaged at 1960 microseconds
at a distance of 0.65 meters;
the speed of sound was found
to be 331.633 m/s.
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Calibration test- 0 meters apart
Thousands (microseconds)
Then the equation previously
listed in the document was
used, v= 331.4 + 0.6Tc, along
with temperature data collected
to find the speed of sound. It
was found to be 345.932 m/s.
90
80
70
60
50
Time Elapsed (micro)
40
30
20
10
0
0
50
100
150
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1
10
19
28
37
46
55
64
73
82
91
100
109
118
127
136
145
Hundreds (microseconds)
The percent error of this
Calibration Test- 0 meters apart
test was 4.133%, which
is reasonable
6
considering the
5
microphone and
speakers were not yet in
4
the boxes and therefore
3
Time Elapsed
slightly varied in
(micro)
distance and moved
2
around with bumps in
1
the table. When secured
to the boxes at a farther
0
and more precise
distance the percent
error will be much less and the data will show a change in the speed of sound as the balloon
ascends.
In order to calibrate the sensor so that when the speakers and microphone are touching the time
elapsed is zero, we found this time elapsed when the speakers and microphone are pressed
together and subtracted this time out of our calculated time.
The graph of tick numbers vs. microseconds shows the approximate number of error readings
that were acquired during the calibration test. The extremely large values will now be taken out
of the average readings of time elapsed, because they are random
inaccuracies. Without these random readings, the time elapsed is
quite constant, as shown by the graph below. The second
calibration graph is the same data, with just the scale changed in
order to provide perspective.
6.7 Camera Test
In order to achieve mission success, the camera must work
throughout the flight. The camera was run multiple times
during various testing times. It collected pictures every time
without experiencing problems with turning on or off.
Furthermore, the camera was included in the dry ice test to
verify its ability to continually capture photographs. Some
pictures from the tests are included to the right.
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6.8 Wind Test
Thousands (microseconds)
Because of the concern
Wind Test- 1.364 meters apart
with the sound of wind
affecting the speakers and
30
microphone during flight a
25
subsystem test was
20
preformed while placing
the apparatus next to a fan.
15
This simulated the sound
Time Elapsed
10
of wind affecting the
5
experiment. The resulting
0
data turned out to be just
0
20
40
60
80
as consistent as the data
Thousands (ms)
received without the fan
running. The graph on the
right shows the total time elapsed, in microseconds, vs. the time elapsed while the sound travels
from the speakers to the microphone.
7.0 Expected Results
Through the mission the BalloonSat is expected to record and retrieve accurate data from the
various sensors onboard. The data is expected to prove the following predictions to be true.
In regards to external temperature, it is expected that there will be a decrease in temperature until
the satellite passes the ozone layer. Past this point, the temperature should increase due to solar
radiation. As the satellite descends, the sensor will record this data in the opposite order and at a
much faster rate. This is due to the satellite experiencing free-fall, and hence, traveling at a faster
rate.
It is expected that the internal temperature will decrease at a less dramatic rate than the external
temperature. Since the satellite is properly insulated and heated it is predicted that the satellite
will remain warm enough to properly function.
By looking at the data recorded by the accelerometer, it is expected that the graphs show an
initial upwards acceleration at the launch of the satellite, a gradual decrease in acceleration as the
satellite approaches its maximum height, and a highly varied acceleration in all three axes during
descent. The acceleration during descent is anticipated to be highly variable because the satellite
will experience a highly turbulent descent.
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Through data from the anemometer it is expected that the wind speed will vary during the entire
flight. This is mainly a result of jet streams. The humidity is expected to decrease upon ascent
and decrease during descent
because there will be fewer water
molecules at high altitudes.
Another expectation is that the air
pressure will decrease during
ascent and increase during
descent. This would most likely
occur because there will be fewer
molecules in the atmosphere as
the altitude increases.
After the flight, the data is
predicted to illustrate how the
atmosphere changes as the
BalloonSat increases in altitude
and how these changes affect the
speed of sound. Research has
shown that the main factor in the
change in the speed of sound is
temperature differences.
Therefore, it is predicted that the
speed will fluctuate as temperature
does; meaning, the speed of sound
will decrease as temperature
decreases and, after the
Tropopause, increase as temperature
increases.
Image found at:
http://www.centennialofflight.gov/essay/Theories_of_Flight/atmos
phere/TH1G1.htm
The image found at the website of the US Centennial Flight Commission, shows an example of
what the results may be. The speed of sound line directly correlates with the temperature line,
and the air pressure and density have little to no effect.
Results similar to this are expected. If any large differences occur they must be looked into and
the cause determined.
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8.0 Launch and Recovery
8.1 Pre-Launch
Launch day is expected to occur on December 1st 2012, weather permitting. Apollo 18 shall
gather before leaving to the launch site to run through a checklist to determine that all systems
are functional. This includes the two Arduinos, two heaters, and digital camera. All team
members will then follow Professor Koehler to the launch site in Windsor, CO. Upon arrival
preparations will be made to launch all payloads in the Gateway to Space class. This will involve
tying all the satellites to a string which is connected a weather balloon. For the quality of the
experimental data, Apollo 18 requests to be on top of the balloon string, to decrease the possible
whip and loss of integrity of the structure, and to have the least likeliness in change of distance
between our boxes. The balloon will be filled with helium and is expected to burst at
approximately 30 km. After everything is ready, the team will turn all systems on and verify their
activation with the outside indicator lights. Peter and Cody will launch the satellite. Flight time is
expected to be around 4 hours, and recovery members will track the string of satellites as it flies.
The satellite will be retrieved by at least one team member after landing in an unknown location.
Post-launch & retrieval, the team will open the bottom box of our satellite and remove the SD
cards. The data will be downloaded from the SD cards so that Apollo 18 may decipher the
readouts of its many sensors. Then the speed of sound will be calculated using our temperature
equation, as well using our experimental data and speed equation. Excel will be used to
rigorously analyze all the findings.
8.2 Post-Launch
Due to high winds on December 1st 2012, the launch was postponed to December 2nd 2012. All
of the teams left Boulder, Colorado at 5:00am. When the team got up to the launch site in
Windsor, Colorado, Apollo 18’s satellite was placed at the top of the string closest to the
hydrogen filled balloon. When Maggie and Cody attempted to turn the satellite on, the camera
lens caught on the foam board structure and would not open. Peter was able to move the lens out
of the way so that it could move past the outside of our box. Maggie and Cody launched the
satellite. After the second balloon was launched, the recovery team received two walkie-talkies
and two maps of Colorado. Maggie, Peter, Chris, Cody, and Jared went on recovery. After the
second balloon was launched, the caravan of vehicles left the launch site in Windsor, Colorado.
The balloon did not burst like it was supposed to so the satellites were cut from it at 99,403 feet.
The recovery caravan then stopped at a rest stop in Sterling, Colorado to figure out where the
satellites had landed; this is also the time when the people from the second balloon separated
from the caravan to find their balloon. All cars then got back on the road and crossed the border
into Nebraska. After driving down a dirt road, all of the cars stopped and everyone got out at
12:15pm. Students all ran through the corn field to find the satellites lying in a straight line.
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Apollo 18’s satellite’s structure was completely intact; surprisingly, the satellite was still beeping
when we found it. After everyone had taken pictures of the satellites as they were when they had
landed, all of the groups posed for pictures with their satellites. Apollo 18 then stopped at a
Wendy’s in Sterling, Colorado so that we could eat lunch, open up the satellite, and retrieve the
SD cards. Everything inside the satellite was intact and nothing had shifted during flight. Peter
then started to analyze the data on the way back to Boulder.
9.0 Results and Analysis
9.1 Environmental Data
Pressure
The sensor worked well and had a starting pressure of 12.24 psi at launch. There was a low of
.08 psi recorded when the balloon was cut 111.7 minutes into flight. In Nebraska it had a resting
pressure of 12.9 psi. There was a smooth curve to the data and were no extreme outliers in the
data.
Percent Humidity
The humidity sensor had
an initial spike as it went
up through the clouds but
then a rapid drop until it
reached the stratosphere
and leveled off at about
10% with a low of 8.5%.
Once the balloon was cut it
had a major jump. The
humidity during the drop
had a maximum of 63.8%
that slowly dropped back
down after landing. There
were no major issues in
this data.
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Accelerometer
This data was exactly as expected. There were heavy G-forces at launch that tapered off and
went away. Once the balloon was cut there was a spike in forces, throughout the fall there were
large forces and
upon landing there
was another spike in
our data. The data
shows a 3.73 G
acceleration when it
landed. Evidence
indicates that
someone rotated the
box after landing, as
there was a change
in acceleration after
landing. The
accelerometer
worked for the
entire flight.
External Temperature
The external temperature
sensor worked. Upon
ascent, there was an
initial spike in
temperature. After the
short spike, the external
temperature fell to 56.67°C as it travelled
through the troposphere.
Once it hit the
stratosphere there is a
gradual increase all the
way back to -8.06°C
when the balloon was cut.
The temperature fell
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rapidly back down to -57°C as it traveled through the stratosphere again, then raised back up as
the satellite fell through the troposphere until it landed. Once it landed it the temperature rose as
the day went on.
Interior Temperature
The interior temperature went up
once we turned the heater on. It
then dropped back down to about
0°C when the external temperature
was around -60°C. The heater
failed somewhere around 105
minutes in. As a result, when the
satellite fell back through the
stratosphere, the internal temp fell
to -13°C when it landed. Like the
external temperature, the internal
temperature went up as the day
went on.
9.2 Experimental Data
Apollo 18’s experiment proved to
be a success despite
some holes in our
data. The data
collected was not as
complete as initially
hoped, but it did prove
the team’s initial
hypothesis.
The data focused on
for the accurate
speed of sound
reading is the first
solid line of data,
because that is when
the sound first hits
the microphone and thus the time it takes for sound to travel. The other points creating
lines above this initial line were caused by the way the speakers function, and indicated
"ghost" readings of the same pulse that took slightly longer to be received. These ghost
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lines all varied from the initial line by 284 microseconds. Therefore, in order to better filter
our data, the microseconds of these lines were subtracted in multiples of 284
microseconds until all the points almost all of the points are within 40 microseconds of
each other. This
shows a much
clearer graph that
represents the
speed of sound at
our fastest readings,
which are the most
accurate.
The speed constantly
decreases as the
temperature drops
and collected data all
the way down to 60°C. The microphone then cut off until burst. The data after the burst wasn’t as accurate as
earlier in the flight, but when it lands it the data evens out. The speed of sound we record at
launch was 316.78 m/s and the temperature was 2°C. The slowest speed of sound we recorded
was 279.14 m/s at -57°C. To better analyze the data, the speed of sound can be seen here from
these two graphs, both
before and after the graph,
with a computer-generated
line of regression better
delineating the correlation
of the predicted results to
the actual results.
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9.3 Failure Analysis
Initially, the cause of failure of
the microphone during flight was
attributed to the cold
temperatures the satellite was
experiencing at that point.
However, upon analyzing several
environmental graphs, it became
clear that this could not be the
case, because the point at which
the microphone failed to collect
data was right when it entered
the stratosphere, when the
temperature began to increase.
The microphone then starts working again quickly after the string was cut from the balloon.
Besides various properties of the stratosphere that could have caused the microphone to stop
working, Apollo 18 determined the cause of error to be the low pressure at this point of the
flight. When pressure decreases, sound waves become less powerful and therefore quieter,
because of the decreased amount of molecules in the air. Because of this, the microphone may
not have been able to pick up the sound from the speakers at these points, because out code
filtered out all the data not within out expected range and the change in pressure caused the
sound the speakers emitted to be not within that range.
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10.0 Ready for Flight
In order to prepare for another flight there are a few minor adjustments that would need to be
taken care of. First of all, it is imperative to replace the microphone on board with a better
microphone that can withstand harsh conditions and obtain more accurate results. With this
microphone more insulation would be added in the area it would go. Furthermore, all the
batteries must be changed including recharging the camera battery. In order to make room for all
of the new data that would be received on another flight, the microSD cards for the Arduinos
must be cleared as well as the SD card on the camera. Finally, the code would be changed to
lower the speaker threshold to a little under 600 in order to assure sufficient data. Once all of
these changes have been completed it would be important to keep the payload at room
temperature, out of harm’s way. On launch day one would simply activate the switches from
“Off” to “On” in order to turn on all of the hardware. If the launch was more than six months
away from today, the only thing to be worried about is the Canon camera battery. It is important
to recharge this battery the day before launch.
11.0 Conclusions and Lessons Learned
Our team learned a great deal from our failure and successes. We concluded that our failure was
potentially due the environmental factors in the stratosphere that we did not foresee nor could
have tested for before launch. All of our other data came out perfect and was a great
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success. It's important to create a clean and stress free environment within your satellite; more
wires and loose fitting items increases the potential for an unnecessary disaster. One of, if not
the most important lesson learned from building our satellite was that you can never be done
testing. No test is “good enough”. You should be extremely confident in your satellite's ability
to perform its mission and not second guess it. Even more so, you should be able to replicate the
predicted environment your satellite will fly through and see it is more than capable. Lastly,
time management and a good team leader is paramount. Our team had a great team leader who
kept us on track. Because of this, we made deadlines on time with little issue while we saw other
teams around us struggle as they procrastinated. If we were to do it all again, we would know
now that testing the functionality of our mission is critical to our success. In the end, our satellite
was a success. It may not have obtained all the data we asked of it, but of all the things that
could have gone wrong, we created a less than normal satellite that worked really well.
12.0 Messages to Next Semester
One of the most important factors to our success in this class were utilizing the individual skills
of each team member and organizing all our efforts in a cohesive way. We would definitely
recommend focusing on the hardware early on and making sure the data can be recorded,
because we watched so many teams struggle with this even during the week before launch.
Communication was key for our team, and our team leader watched the schedule and made sure
that there was time for everything. Don’t be overwhelmed by everything required of you; just
begin building and eventually everything will get done. But most importantly, think of a
challenging experiment right away, and don’t test handwarmers! But even if your idea isn’t good
enough the first time, there is still time to create a great experiment and have a blast in the class!
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