This document summarizes the Challenge Based Training methodology used to design small liquid rocket engines with engineering students over several years. Key aspects include: - Students are given challenging engineering design problems to motivate learning and applying their skills. They have designed multiple small liquid rocket engines and components. - The program started in 2009 with 4 students designing a 1kN engine. It has since expanded with over 40 students participating across 8 teams designing engines up to 5kN. - Students are guided through the design process in a textbook written for the program. They present their work at symposiums, gaining experience applying their skills. - The program aims to provide more hands-on opportunities for students to gain experience

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DESIGING LIQUID ROCKET ENGINE WITH
THE CHALLENGE BASED TRAINNING METHODOLOGY.
Vládia Perez
Inotech, Rua Prof. Roberval Froes 195, São José dos Campos, SP, vladiaperez@hotmail.com
René Nardi Rezende
Inotech, Rua Prof. Roberval Froes 195, São José dos Campos, SP, renenardi@hotmail.com
Amilcar Pimenta
Instituto Tecnológico de Aeronáutica, São José dos Campos, SP, amilcar@ita.br
Abstract: This is the story of a volunteer based program dedicated to introduce students to the engineering
world. It describes how it all started and developed over the years, the challenges faced and the solutions found
to keep the organization alive and achieving its objectives. Designing small size liquid rocket engines was the
motivator behind a process named Challenge Based Training, that draws on skills students acquires at school,
supplemented by information provided by our organization, to make sure the objectives given to the participants
are met. While interacting with those young engineers to be, we learned how motivated they were to apply the
recently acquired knowledge and surprised by the extra efforts they made to accomplish tasks to them assigned.
Fast forward to 2014 and we will find that 40+ students went through the Program. They designed five engines,
build three of them, designed a propellant injector cold test bench and a hot test bench for the whole engine. On
top of that, a comprehensive work on propellant injectors was developed, with amazing results. We have also
written a book the team works with and supported two Jet Propulsion Symposiums, where the students had the
chance to share with their peers the results of the work. Two new engineering schools have joined the program
recently; one was given the task to design a flight control computer and the other has a group designing valves
for the propellant feed system.
Keywords: Propulsion, training, liquid, rocket
1 Where ideas come from?
ocated on a plateau between the Pacific Ocean and the snow covered Andes mountains, Santiago de Chile,
hosts every two years the FIDAE air show. Having breakfast at the hotel, I decided to take a look at the local
newspaper, or at least doing my best with reading Spanish, trying to get a feeling of the surrounding
environment. On the last page of the Sunday edition there was an interview with the Chilean ambassador, just
returning from his assignment in South Korea. Among others, the reporter asked him why Chile and Korea,
having similar educational level, were so different in technological aspects. The ambassador answered that the
differences were in the opportunities given to students to apply, on their professional life, the knowledge
acquired at school.
A couple of days later, with several hours to spare on a flight back home, started thinking about the
implications of the ambassador’s statement, questioning why there were not that many opportunities for students
to make good use of their talents and what would be needed to turn the situation around.
During the months that followed, ideas were exchanged about what to do next, in terms of turning a concept
into something tangible. The decision process was somewhat confusing at the beginning, as figuring out
immediately what would be an interesting subject to deal with was not an easy task. After some deliberation the
conclusion was that whatever the activity to be chosen would be, it had to be difficult enough to call the students
attention, but feasible in order to keep them interested in accomplish the mission. Working with engineering
students was a natural decision, and on top of that it would be nice to do something related to the engineering
field we are familiar with. At some point along the decision process the conclusion was that designing liquid
L

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rocket engine would incorporate the difficulties we were looking for, and eventually being interesting enough to
the aerospace engineering students we were planning to work with.
Finally, in order to properly deal with the Universities administration, Inotech Ltd., a small not for profit
organization, with no money, no office, not even a desk or a laptop, was founded. At that moment all the
elements required to trigger the “Challenge Based Training” process were in place.
2 How it all started.
Paulo Iscold is a professor of aeronautical engineering at UFMG - Minas Gerais Federal University, the designer
of an aircraft called CEA-308 that broke no less than four world records, and a long time friend. I approached
him with this crazy idea of training some of his students on the arts of designing liquid rocket engine. So, on a
winter day of 2009, I found myself in to Belo Horizonte, MG to be introduced to a group of four brave students
that volunteered for the experimental program. The challenge: they have one semester to learn the technique and
to apply it to the design of a 1 kN ethanol and gaseous oxygen propelled rocket engine, and on top of that serve
as guinea pig for development of the teaching routine.
As Inotech is based in Sao Jose dos Campos, and the students were 400 km away, plans were made for weekly
teleconferences classes, using Skype, supplemented by bi-monthly face to face meetings. It was a nightmare at
the beginning, but it seems that once you get used to virtual classes, it works.
Among the initial tasks given to the students was the selection of a name for the group. It didn’t take them much
to return with an appealing proposal – Rumo ao Espaço – which would translate to English as something like
“Aiming for Space”. The name carries with it the hopes and ambitions that one day the students would find a
chance to apply the skills recently acquired into a real life job. Besides that, the name was so creative that all the
working groups that followed were named “Rumo ao Espaço”, with the addition of a number. For example:
Rumo ao Espaço G-I, Rumo ao Espaço G-II, through Group VIII.
Fig. 1 shows the four member team that gave birth to the program, under the leadership of Ms. Julia. This picture
shows the team at the UFMG Combustion Laboratory, testing a propellant injector. The engine they designed
was built by a private company, under the sponsorship of a Brazilian Government Agency named FAPEMIG,
and it is, since then, waiting for a test bench to be tested.
Figure 1. First team, from UFMG.
3 A text book was in need, so, we wrote one.
We started the program using the reference material available at the UFMG Engineering School’s library, which
happened to be the Sutton/Biblarz and the Huzel/Huang’s text books, supplemented by information found on
websites and guidance provided by Prof. Amilcar. It didn’t take much to realize that it would be much easier to
teach our students based upon a book written in their native language, and on top of that, a book that could
describe the design process under an engineer perspective. The result was a text book that, to the best of our
knowledge, it is the first written in Portuguese to cover the entire design sequence, starting with inputs from the
customer (the so called HLR – High Level Requirements) and offers the reader a sequence of operations to
achieve the final objective, which happens to be the main dimensions of the thrust chamber. Later on, a new
chapter was added, dedicated to share our perspective on propellant injectors design. If we could summarize in a

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nutshell what that book offers, it can be said that it takes the 1950’s rocket engine design parametric approach
(equations, tables, charts, etc) and recycled it in terms of offering a logical sequence that can be better
appreciated when associated with a 21st
century personal computer. The methodology relies extensively on the
inexpensive, high power computer currently available, equipped with a spreadsheet (Microsoft Excell, for
example), a 3D computer aided design software (Dassault’s Solidworks, for example), and, of course, an user
that can handle all the benefits of the information society.
With that book half way done, a new Rumo ao Espaço group was formed. A university named UNIVAP, located
in the same town where Inotech is based, gave us the chance to interact with its students on a face-to-face, more
traditional kind of class. The challenge assigned to the students was the design of a 2 kN, bio-Kerosene and
liquid oxygen propelled liquid rocket engine. Fig. 2 shows part of the eight student team, at the area donated by
UNIVAP for their use. On top of the table there are two engines, the 2kN designed by them (on the right) and the
0,5kN (on the left side) designed to calibrate the routine describe on the textbook.
Figure 2. Second team, from Univap.
4 The case for the test bench.
At a very early stage into the program we felt the need for test benches to help us confronting the performance of
the products built with the theoretical model upon which they were designed. Coincidence or not, two things
happened almost simultaneously. It all started with an invitation from a local technical school named SENAI to
help a group of mechanical desig students with their graduation work. The challenge presented to them was, of
course, the design of a propellant injector test bench. We provided the specification, worked with them on the
initial stages of the product definition and from that point on they did the work by themselves. Figure 3 shows
the team at the presentation ceremony and the test bench they designed.

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Figure 3 – The SENAI team.
Almost at the same time, I got a phone call from a student saying he and two friends were in Sao Jose dos
Campos, after traveling the 400 km from Belo Horizonte. Bruno told me they heard about Inotech and the work
with engineering students and would like to talk with me. How could I say no ???? I asked them to meet me that
same day at home and to explain me what they had in mind. After some talking with the PUC-MG mechatronics
students, we came to the conclusion that the best way to use their skills would be the designing of an engine test
bench. The engagement process followed the same procedure we were now used to: set a challenge, give the
students the initial requirements, provide some guidance and get out of their way.
Figure 4 – PUC-MG team
5 Assigments are getting more complex.
Our activities were expanding, with new students joining the Program, tasks getting more sophisticated,
followed by substantial increase in the work complexity. By late 2010, just before we initiated the work with
another team, we had the honour to receive support from Prof. Mautone, the head of the aerospace engineering
department at UFMG. With Prof. Mautone acting as a consultant and the recently finished Handbook being used
for the first time as our primary source of reference, the work started on the 5 kN, ethanol and liquid oxygen
rocket engine. On Figure 3 we have, on the left, the propellant injector during the manufacturing process, and, on
the right, the completed unit with a dummy acrylic combustion chamber attached to it. The acrylic chamber is
needed during the injector cold test, to help visualize the propellant atomization taking place inside the
combustion chamber. The propellant injector was manufactured under the sponsorship of a Brazilian
Government agency named SENAI.

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Figure 5 – The 5 kN propellant injector
So, at that point we had, besides Inotech, received support from Utec, UFMG, Univap, Fapemig and Senai.
Then, by mid 2012 while preparing a suitable challenge for Group VI, we found out that the Brazilian Space
Agency had a need for a retrorocket for its microgravity experiments vehicle, called SARA. We approached the
Department in charge of the project and asked if they were willing to share some of the engine requirements with
us. Based on the information received (thrust, propellant, firing duration, envelope), we challenged our team to
develop the SARA’s 1 kN, hypergolic engine. On Figure 4 you can see G-VI at work, on the place made
available to them at UFMG, and on the right, a photo of the engine mock up. We went even further, building and
cold testing a fully operational propellant injector.
Figure 6 – Group VI at work and the result of its efforts, the 1 kN SARA engine (mock-up).
Fast forward to 2014 and we will find that a significant number of students went through the Program. They
designed engines, build some of them, designed a cold propellant injector test bench and a hot test bench for the
engine. A comprehensive work on propellant injectors was developed, with interesting results. We have also
written a book the team works with and supported two Jet Propulsion Symposiums, where the students had the
chance to share with their peers, the results of their work. Two new engineering schools joined the program
recently, one was made responsible for a flight control computer and the other is designing valves for the
propellant feed system.
What lies ahead of us? The program is still alive and doing well, with new groups planned for 2014, and the
near future. We dream about having a test bench to check the performance of our engines, and would welcome a
team to design the flight version of the 1 kN engine. We would like to put together a group to design a flying
machine around that engine. We may have accomplished something, but we would like to go even further with
our Challenge Based Training, aiming for space, or, as we say in Portuguese, Rumo ao Espaço.
6 Acknowledgments
The authors acknowledge the contributions of the universities, agencies and private companies, whose support
made the work behind this report possible. Many thanks go to Prof. Eduardo Mautone and Prof. Paulo Iscold,
both of them from UFMG, Prof. Euzébio Souza from UniBH, Prof. Wellerson Jr. from PUC-MG, Profa.Viviane
Valverde from SENAI-SJC and Alex Siqueira from UTEC.