The document summarizes the development process of a device to characterize combustion rates in rocket engines by a team called Rocket Dynamics. It describes their project management methods including defining roles and schedules. It discusses gathering customer needs through interviews and defining product specifications using a quality function deployment tool. A variety of concepts were generated and the bulkhead concept was selected using a screening and scoring process. An FMEA analysis was planned to evaluate weaknesses in the selected design.

1. Rocket Dynamics
Kevin, Steven, Bronson
BYU - Idaho
ME 380
July 18, 2016

2. 1 Introduction
The vision of the Rocket Dynamics team is to develop a reliable device that can be used
to characterize the combustion rate within a rocket engine in order to more effectively
optimize fuel mixture. This report contains the the product development process used to
create the device from start to finish. Each section is in chronological order giving an
outline of the step-by-step development process.
2 Project Management
2.1 Methods
The planning process consisted of three stages where each team member contributed their
thoughts and opinions in order to get a project management system. To begin, the team
compiled a list of tasks and sub tasks that needed to be accomplished in order to create a
final product. Next, the list was then adjusted to fit the executive summary report schedule
in order to meet report due dates. In the last portion of the planning process, the product
vision statement, mission statement (Table 1), team logo, teams roles, and collaboration
method were all decided upon. All the content from the three stages were compiled and
made accessible to all the team members.
2.2 Results
The Rocket Dynamics team’s mission is to develop a non-intrusive device to characterize
rocket motor combustion allowing rocket researchers to more effectively optimize engine
2

3. Table 1: Mission Statements
Product Description -Develop a device to characterize the burn rate of
rocket fuel allowing researchers and students to more
effectively optimize engine thrust
Benefit Proposition -Understand how different motor designs influence
burn rate can allow for optimal engine thrust
Key Business Goals -Accurate data output
-90% Reliablility
-Increase compition rocket thrust 10%
Primary Market -Educational rocket design teams
Assumptions and Constraints -Compition size rockets
-Low cost budget
-Easy user interface
thrust. In order to reach this goal a project management system was created as a result
of the three stage planning process. The project management system outlines the team
member role in order to set the expectation for each member’s contribution. To keep the
team on task, a project schedule was also created outlining the report due dates and project
milestones from start to finish. The team decided to use Google Drive to post ideas, set
meeting times, and as a method to collaborate individual work. Now that every member
has a role, the team has a schedule, and a system of communication is in place, the Rocket
Dynamics team is ready to get started.
2.3 Discussions
Following the project management system will be how the Rocket Dynamics team mem-
bers will fulfill their product vision and mission statement. The project management system
presented in this report is subject to change as the development process proceeds in order
to address any issues the team might encounter as the design process progresses. But for
now, the current project management will be a good starting point for the Rocket Dynamics
3

4. team to start designing a combustion sensor.
2.4 Conclusion
The three stage planning process resulted in the project management system that outlines
how the Rocket Dynamics team will create a combustion sensor from start to finish. Rocket
Dynamics team plans on following the project management system in order to assure that
all reports and stages of development are completed on time. The project management
system will also outlines the roles and responsibilities of the each team member so each
member will equally yoked. With the team roles and the schedule outlined, the team will
be able to operate more effectively through the development process which will ultimately
result in a quality combustion sensor.
3 Customer Needs
3.1 Methods
In order to gather customer needs regarding to the rocket motor combustion sensor, Rocket
Dynamics team had to first identified the intended customers, decided track data and then
contact them. Not everyone uses rocket engines on a regular basis or ever, so identifying
who the actual customer was critical. To do this, Rocket Dynamics team compiled a list
of possible customers for the product. This list was then divided up into two groups based
on how the customer would be contacted and interview. Group one would be contacted
in-person and group two would be contacted via email or phone. The data from these
interviews would be recorded by hand written notes and then compiled for comparison.
4

5. Team members were assigned certain customers to contact and interview to increase the
number of customer contacts. With all the customer data gathered and compiled, the Rocket
Dynamics team will analyze and determine how it will be best applied to the product design.
3.2 Results
We found six key needs statements from our interviews and research that we conducted.
The full list of all the needs statements and the hierarchy rating may be found in Table 2.
The research gave us a lot of ideas to expand and to test in the early development stages of
our product.
We formed the hierarchy based on where we would spend our time. The task we will
spend the most time on are essential to our final design. The rest of the needs that could be
incorporate will be done according to priority and time given in our schedule
3.3 Discussions
We decided to collect our data from our customers by conducting interviews in person and
through email. We found the interview to be very useful because it brought up some needs
we had not considered before that point. We had considered the need of making a project
reusable and cost effective, but after conducting our interviews we realized that in order to
accurately measure burn rate we might have to insert tools in the rocket motor to accurately
measure temperature. Doing so would destroy our tools to measure burn rate. In order
to assure that our product is both accurate, reusable and cost effective we need to include
something cheap that can be easily replaceable in our design.
5

6. Table 2: Custumer Needs Statements
Capability scale (1-5)
Accurately measure burn rate (Single method) 1
Data aquired from actual motor performance 1
Reusable base part 1
Affordable replacement part 2
User friendly interface 3
Accurately measure burn rate (Multiple method) 4
Simple setup 3
3.4 Conclusion
The costumers are essential to the design process and must be considered in order to de-
velop a successful product. Interviews were helpful to gather insight on the functionality
and usability of our design. The different perspectives have helped us better understanding
how to design our product to meet customer needs. Ultimately, the design process will be
shaped by the data gathered by the customer needs process.
4 Product Specifications
4.1 Methods
In order to integrate the customer needs into the design process, the Rocket Dynamics
team implemented House of Quality (HOQ) from the Quality Function Deployment (QFD)
tool. HOQ focuses just on one aspect of the QFD that turns customer needs into engineer-
ing characteristics or product specifications. The Rocket Dynamics worked through HOQ
rooms 1-5 which allowed all the customer needs to be translated into design characteristics
and then be ranked. With the ranked design characteristics, the team was able to filter out
6

7. different characteristics that werent of great importance in order to more fully focus on the
top three. The top design characteristics were then moved on to be product specifications.
And this was the intended outcome, to translate the customer needs into a product speci-
fication so that the voice of the customer would be represented throughout the rest of the
design process and in the final product.
4.2 Results
To meet customer needs, we came up with 7 engineering characteristics (see Table 3),
which are, in order of ranking from highest to lowest, available accessories, required num-
ber of attachments to the rocket motor, data output, re-usability, digits of accuracy, effect
on motor performance, and cost of replacement parts. Available accessories will be mea-
sured will be measured as a minimum quantity, and number of attachments to the rocket
as a maximum quantity. We decided that the data should be outputted in SI units, with the
ability to be saved to a spreadsheet; this will be measured as a binary value. Re-usability
will be measured in the number of tests it will can successfully complete. Digits of accu-
racy will be measured in the number of decimal places, and effect on motor performance
will a binary value. Finally cost of replacement parts will be a maximum dollar value.
4.3 Discussions
The house of quality helped clarify what qualities realistically need to be incorporated
in the design. The house of quality help combine the needs of the costumer as well as
the engineering needs. It was enlightening to see how some qualities, from an engineering
perspective, we thought were not the top priorities were key parts to the design. As shown in
7

8. Table 3: Product Specifications
8

9. the appendix, the qualities of the base products holds the most values to the design because
it assures that these items work. The base product is key because both the entire product is
dependent on the qualities it hold. We learned that the base product must need to following
qualities; be powerful enough to handle multiple inputs, exportable data, expandable for
improvements, and meet the accuracy needed. The base parts is connected to all aspects of
the product specification.
4.4 Conclusion
The product specification is an important step in making a successful product. Under-
standing that there are both customer and product needs that contribute to the quality of a
product is important. Evaluating the needs together and understanding how certain qual-
ities influences both the customer and product needs has allowed us to focus our time on
what matters most. We discovered that the base part holds the most amount of influence
in making a reliable, working product. Following the hierarchy of what will improve the
product and customer satisfaction has allowed us focus on improving our chances for suc-
cesses. Overall, the house of quality is an important tool in the design processes and will
be used by our team through the rest of the design processes but more especially during the
concept generation where the house of quality results will be used to guide the generation
process.
9

10. 5 Conception Generation
5.1 Methods
There were two main phases of the concept generation process that the Rocket Dynamic
team engaged to more effectively generate all possible ideas. The two phases were external
and internal concept generation. The external method took place first and involved team
members individually searching out possible solutions that already existed resources list
in Table 1. The ideas were then presented the to the team with no critique from the just
question and then recorded. Internal concept generation came next, which consisted of
every team member presenting the ideas they hand individually came up with on their
personal time. The Rocket Dynamics team used a modified De Bono’s hat method to
present, build upon, and filter through ideas. First all ideas were presented no matter how
wild, then everyone built upon the current ideas that were presented in Gallery form, and
then last everyone expressed the major hold backs from each idea. All the ideas from
internal and external sources were sorted into a matrix so the ideas could be more easily
compared during concept selection as seen in Figure 1.
5.2 Results
In generating concepts for how to measure burn rate inside a rocket motor, the majority of
our ideas fell into three main categories: various methods of measuring temperature with
a thermocouple, various methods of measuring temperature with an infrared thermometer,
and using some form of internal probe. There were other ideas, but all were unique enough
that they didnt fit in any specific category.
10

11. Figure 1: Concept Generation Matrix
5.3 Discussions
When trying to generate concepts for our product, we found the method that was most
effective for us was brainstorming. When sharing ideas with each other, we found that
each person had unique ideas that the group could build off of, but otherwise wouldnt have
conceived on their own. At times a members of the group could also find an alternate
application for concepts that had previously lost popularity with the group. The disadvan-
tage of brainstorming however, seemed to be that the group would occasionally focus on
further developing a single concept, without trying to come up with anything new. The
external methods we tried had the advantage of bringing in knowledge and concepts that
were beyond the scope and education of the group itself. Combining internal with external
methods allowed us to use the knowledge we otherwise would not have had to inspire novel
concepts within our group.
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12. 5.4 Conclusion
With the goal of developing a reliable device to characterize rocket engine combustion rate,
the rocket team worked through the concept generation process considering both internal
and external sources. The goal was to generate all possible ideas now so that they dont
get discovered later in the product development process. Ultimately, the team was able to
generate some novel concepts that everyone felt confident would give us a great list of ideas
to work with during the concept selection process.
6 Concept Selection
6.1 Methods
The Rocket Dynamics team used the concept selection funnel (shown in Figure 2) not only
as a guide for screening and scoring concepts but to facilitate further concept develop-
ment.The scoring process was designed to further filter concepts that made it through the
screening process by quantify the strength of each concept. The criteria comparison matrix
can be seen in Figure 5 shows the different criteria categorizes that were compared. After
the comparison matrix was created the Rocket Dynamics team then normalized comparison
matrix by dividing each column cell by the column sum and then taking the sum of each
row to show the criteria weight as seen Figure 5. To ensure the team was consistently in
the criteria comparison, a consistency matrix was created, as seen in Figure 6, that required
a consistency ratio (CR) less than 0.1. Once the CR was less than 0.1, then each concept
that made through the screening process was scored according to each criteria category in a
decision matrix. The results from the screening process were put into the decision matrix.
12

13. Figure 2:Concept selection funnel
This last matrix seen in Table 4 gives each concept a total score which determined what
concept would be developed.
6.2 Results
The criteria comparison matrix shown in Figure 6 clearly exhibits what our design param-
eters are along with the needs of our customers. The criteria comparison matrix clearly
shows that accurately measure burn rate (single method) and data acquired from actual
motor performance, defines the product by caring the most weight in the comparison pro-
cess. From the decision matrix, found in Table 4, we see that the Bulkhead has the highest
score, followed by the Wired Fuel Cell, and last the Infrared Thermometer concept. (the
concept scoring table shown in Table 4 displays these results in greater detail). With the
final concept scores, it was easy to determine that Bulkhead will be used for prototyping.
13

14. Table 4: Concept Scoring Results
Criteria Concepts
BH IR WFC
Weight Score Weight Score Weight Score Weight
Accurately measure burn 0.357 4 1.427 2 0.713 5 1.783
rate (Single method)
Data aquired from actual 0.386 4 1.544 2 0.772 2 0.772
motor performance
Reusable base part 0.097 5 0.486 5 0.486 2 0.194
Affordable replacement part 0.056 3 0.168 1 0.056 2 0.112
User friendly interface 0.047 3 0.141 3 0.141 3 0.141
Accurately measure burn 0.044 2 0.088 2 0.088 2 0.088
rate (Multiple method)
Simple setup 0.044 4 0.177 1 0.044 1 0.044
Total Score 4.031 2.301 3.135
Rank 1 3 2
Develop? Yes No No
6.3 Discussions
Initially narrowing down and eliminating ideas that were unfeasible or too costly was easy,
but the few ideas that remained were all good. Just the screening process did give enough
reason why we should select one over another. Having the criteria and decision matrices
however, simplified this portion of the selection as well as represented the customer needs.
The initial setup was somewhat tedious, but after it made it easy to the advantages and
disadvantages of the the various methods based on what we considered important. With a
final score for each concept it was clear which one would best fit the customer needs and
satisfy out product vision statement.
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15. 6.4 Conclusion
The screening and scoring process allowed the Rocket Dynamics team to be more methodi-
cal about the concept selection process. The criteria comparison method clearly represented
the needs of the costumer and showed which concepts would perform best with the spec-
ified criteria. It allowed for each concept to be compared against the criteria as well as
against other concepts that made it through the screening process. The concept that meets
the highest criteria was the bulkhead and will be further analyzed using the FMEA process
which will determine any design weakness and potential solutions.
7 FMEA
7.1 Methods
The FMEA process was divided into two sections. Section 1 consisted of compiling all
the data necessary to calculate the RPN for each failure effect and Section 2 consisted of
compiling and calculating data needed to determine the Impact number for each failure
effect.
First a list of all the parts and functions of the product were compiled along with
their respective failure modes, failure effects, and failure causes. Then the severity (S),
occurrence (O), and detection (D) for each failure effect was quantified using the descriptive
scales found in Tables 9, 10, and 11. All the data was put into the FMEA matrix and then
the Risk Priority Number (RPN) was calculated for each failure effect to finish Section 1
of the FMEA process.
15

16. Section 2 started by coming up with recommended actions that could be taken to
mitigate different failure modes of the product. Then a post preventative action severity,
occurrence, and detection number was determined using the scales found in Tables 9, 10,
and 11. With new (S)-(O)-(D) values, the post RPN (pRPN) number was generated allow-
ing us to determine the Impact value of each potential failure by calculating the difference
between RPN and pRPN. Last step was to assign Do-Ability number to each recommended
action using the number scale found in Table 12.
7.2 Results
The results from our table shows that we have several ways of failure. There is a total
of 13 different potential failures the product has that are at a severity 10. Short circuit,
damage sensors, and burnt material are the majority of the problem. These problems are at
risk because of the heat and vibration during motor testing. The recommended actions to
solve majority of these problems is to assure that all sensors are protected from the heat, all
electrical equipment are in a protected area, and are properly mounted on the testing stand.
The affect of such recommended actions on the Risk Priority Number (RPN) can be seen
in Figure 3. Notice that the greater the difference between RPN and pRPN, the greater the
impact number. Then each recommended action is given a Do-Ability value, correlated to
the value scale found in Table 12, in order to scale the action’s difficulty.
7.3 Discussions
From observing the results, it appears that the all the failure modes that have the largest
impact are those that affect our ability to collect data. This makes sense because collecting
16

17. Figure 3: RPN and pRPN Comparison Chart
data is the main function of our product. Most of the causes of failure appear to related to
the inherent danger of working with combustible materials, but knowing this, gives us the
opportunity to take the necessary action to address potential failures. Overall it is important
that each failure mode be addressed and that preventative measures are built into the design
of the product.
7.4 Conclusion
The Rocket Dynamics team used the FMEA process to analyze the potential weaknesses of
the burn rate sensor design so that the design could incorporate the necessary preventative
measures. The FMEA analysis gave great insight into the impact of potential product
failure modes and their root causes. In general, it was found that working with combustible
material was the root cause of failure for almost every part and product function. In the
end, every one of the failure modes will be addressed and preventative measures will be
built into the design of the product which will be outlined in the detailed design section.
17

18. 8 Detailed Design
8.1 Methods
The detailed design report was divided into two separate sections, electrical and hardware,
so that individual assignments could be made allowing the Rocket Dynamics to work more
effectively. It category includes mainly the setup instruction and any special instructions
needed to acquire certain parts (e.g. manufacturing instructions). The electrical section
includes the wiring schematics (sensor wiring setup), electronics setup, and programming
code. The hardware section includes the pitot tube setup, rocket and test stand setup, and
manufacturing instructions for parts made in house. In parts that are needed for both sec-
tions were communicated through the parts and material list. This list gives the reports
the costs of all the parts and materials that needed for the final design. With the parts and
material lists, electrical setup, and hardware setup all the information needed for setup and
use by a third party is covered.
8.2 Results
The setup for the product involves several different assemblies and combined all together
into a single product. The parts and material list, found in the Table 5, will show every-
thing required for the overall assembly and the total cost of the necessary items being 655
USD (not including any custom manufacturing cost). For the setup of the pitot tube, the
instructions can be found in Table 6 along with a video link for the overall setup of the
rocket assembly. The wire schematics for the sensor setup can be seen in Figure 5-7 and
all the necessary links to instructions for the electronic setup are listed in Table 7-8, along
with the necessary code to run the program. With that, all the electrical and hardware setup
18

19. instructions have been provided along with links for detailed instructions. Lastly, each part
of the rocket and test stand can be manufactured with the CAD drawing found in Figures
8-11. After each component of the rocket is manufactured the can be assembled using
the previously mentions video link found with the pitot tube instructions. The estimated
time for the entire setup was about 25-30 minutes with just one experience person doing
all the work. This however doesn’t include the time needed to order parts and get custom
part manufactured, this could take up to 3-4 weeks. Finally, the overall device layout and
instructions on how to interpret the data is shown in Figure 4.
8.3 Discussions
The method of compiling all the material for the detailed design report worked great al-
lowing the team to divide up all the material that needed to be gathered. The overall cost
of the device came out to be a little more than anticipated with a total of 655 USD. The
overall assembly of the product can be challenging and a time consuming process, specif-
ically wiring the sensors to the ADC. Even though it will take some time to assemble it
all together, it will be very easy to reuse and further develop. Although we provided the
schematics for the rocket motor and stand, the pitot tube assembly should work with dif-
ferent rocket models and rocket stands. We decided to use videos and other visual aids to
help clarify and simplify the setup and manufacturing process. it was found the estimated
time for the entire setup was about 25-30 minutes, with just one person doing all the work,
while the actual burn rate test itself takes just a few seconds.
19

20. Figure 4: Device Layout
20

21. 9 Conclusion
The goal of the Rocket Dynamics team is not only to create a reliable burn rate sensor
device but also a device that can be recreated by an outside party. In order to increase
the repeatability of the device, the Rocket Dynamics team tried to simplify complex setup
instructions by including links to access more descriptive presentation of setup instructions
that couldn’t be included in this report (e.g. videos). With the electrical and hardware setup
instructions created and compiled, along with the parts and material list, all the necessary
details for an outside party to recreate the Rocket Dynamics’ burn rate sensor have been
captured. In summary, we found that the during the setup process the sensor and ADC
setup took the most time due to all the wires involved so adequate time needs to be allotted
to this portion of the setup. And it is especially important that the sensor setup isn’t rushed
as this can lead to data collection errors causing the device to fail. Also, the price could be
reduced with a little more time shopping around online, which will need addition time, if
a budget is more critical than timing. Custom manufacturing charges weren’t included in
the overall total cost and this will not only take time but more money as well to get custom
parts built.
21

22. Table 5: Parts and Material List
Parts & Materials Quantity Price
Wires, female to female (2.54 mm) 2 (40pc set) $4.84
Pressure Transducer (500 psi) 1 $19.79
Pitot tube stainless steel, (.03125 Diameter x 8.625 Insertion length) 1 $52.72
Rubber Tubing (5/16 ID, 1/2OD 3/32 Wall black opaque) 20 ft $34.12
Raspberry pie (starter kit) 1 $70.00
Thermocouples (K type) 2 (4 pack) $12.86
Adafruit ADS1015 ADC 3 $50.46
Aluminum bar stock (3 OD, 5 long) 1 $19.00
Graphite Bar 1 $16.80
Resistors (150 ohm) 3 $0.10
Resistors (100 ohm) 3 $0.10
9V Batteries 6 $0.60
D Batteries 8 $1.15
Pressure Transducer (2000 psi) 2 $85.00
Load Cell (max load 800 kgs) 1 $234.95
Tripod 1 $16.98
Electric Wire 305 m $6.79
Phenolic Liner (2.75 OD) 1 $11.25
Tube Clamps 6 $0.74
Tube Adapters 1 $2.40
Pressure Transducer Adapter 3 $12.99
Tripod Stakes 3 $1.50
Flanged Head Bolts 2 (6 pack) $3.29
Total $655.14
Table 6: Pitot Tube Setup Instuctions
Step #
1 Connect tubes with bracket to the back part of the pitot tube.
2 Taking the tripod mount screw in the pitot tube mount to the tripod mount.
3 Drill small holes for stakes into each leg of the tripod
Video Link https://drive.google.com/open?id=0B0xHNSnMiFo6UTR0N WYwaVA4ZFE
22

23. Figure 5: Results from the criteria comparison matrix
23

24. Figure 6: Results from the normalized comparison matrix
24

25. Table 7: Raspberry Pi, ADC, Programming Setup Process
Step #
1 Setup Raspberry Pi (see Table 4 for detailed how-to instructions for each step)
2 Install Raspberry Pi OS
3 Setup Local Domain Name for Raspberry Pi
4 Setup Wifi Adhoc Raspberry Pi
5 Setup Remote Access (SSH) to Raspberry Pi
6 Setup the Anaglog-to-Digitial Converter (ADC)
7 Connecting ADC to Raspberry Pi
8 Input the specified programing code
Table 8: Raspberry Pi, ADC, and Programming Code Detailed Instructions
Step #
1 Raspberry Pi Setup
(https://www.raspberrypi.org/documentation/setup/)
2 Raspberry Pi OS installation
(https://www.raspberrypi.org/documentation/installation/)
3 Raspberry Pi Local Domain Name
(http://www.howtogeek.com/167190/how-and-why-to-assign-the-
.local-domain-to-your-raspberry-pi/)
4 Raspberry Pi Wifi Adhoc
(http://slicepi.com/creating-an-ad-hoc-network-for-your-raspberry-pi/)
5 SSH to Raspberry Pi
(https://www.raspberrypi.org/documentation/remote-access/ssh/README.md)
6 Setting up the ADC
(https://learn.adafruit.com/adafruit-4-channel-adc-breakouts/assembly-and-wiring)
7 Using ADC with Raspberry Pi
(https://learn.adafruit.com/raspberry-pi-analog-to-digital-converters
/ads1015-slash-ads1115)
8 Python Code
(https://github.com/supergeektuber/380 Sensors/blob/master/seonsors.py)
25

26. Figure 5: ADC Wiring Diagram with letter ports (marked-off lettering are ports not be
utilized)
26

27. Figure 6: Pressure Transducer Wiring Diagram
Figure 7: Load Cell Wiring Diagram
27

28. Figure 8: Nozzle Sleeve CAD Drawing
28

29. Figure 9: Motor Casing CAD Drawing
29

30. Figure 10: Nozzle CAD Drawing
30

31. Figure 11: Bulkhead CAD Drawing
Table 9: Occurance Scale
Table 10: Severity Scale
31

32. Table 11: Detection Scale
Table 12: Do-Ability Scale
32