675.731.3VL - Spacecraft Propulsion Systems
Description
The intent of this class is to teach the basics of propulsion such that you will be able to make informed decisions about which sort of system would be best for a particular application. To do this, the class starts with a basic primer on the physics of propulsion and then covers key elements of the various types of propulsion systems that are typically used on spacecraft, including chemical and electric systems, and also some types of system not typically used now, but that might be available in the future (e.g., nuclear propulsion, matter/antimatter propulsion). In the class, you are introduced to how a propulsion subsystem is used and how it interacts with the rest of the spacecraft, so it can be seen from a system perspective and not just from the subsystem view. Key pros and cons of each type of system presented are discussed, as well as key constraints and failure modes. Subsystem components and performance characteristics are introduced and then used in examples from actual spacecraft to explain why these systems were selected for flight. Then, you are shown how to specify a propulsion subsystem and trade various subsystem types against each other, how to size them, how to integrate and test them, and ultimately how to fly them.
Instructors
Carl Engelbrecht
Stewart Bushman
Course Structure
The course materials are divided into modules which can be accessed by clicking Modules on the left menu. Each module will include the lecture presentation and the homework assignment for that week. You are encouraged to preview this material before the lecture. A recording of the lecture and of the related Office Hours will also be posted there. Some modules will also include a quiz or exam which will not be accessible until the prescribed time in the class when you will take the quiz/exam. All modules run for a period of seven (7) days. Homework will be due by the end of the sixth day (i.e. Sunday night) of the module to give me enough time to grade them before the next lecture. You should regularly check the Calendar and Announcements for any possible exceptions to this information.
Course Topics
Introduction to Propulsion
Cold Gas and Monopropellant Thrusters
Bipropellant Engines
Solid and Hybrid Rocket Motors
Electric Propulsion
Advanced Propulsion
Feed Systems (Liquid)
Pressurization Systems (Gas)
Spacecraft Interfaces and Final Selection of a Propulsion System
Subsystem Design Effort and Specification Preparation
Feed System Schematics
Integration and Test of Spacecraft Propulsion Systems
Flying Your Spacecraft Propulsion System
Course Goals
To identify and describe the fundamentals of spacecraft propulsion, and to provide the students with practical tools and resources necessary to design a propulsion subsystem concept. That knowledge will then be used to design a propulsion system in a semester-long design effort.
Course Learning Outcomes (CLOs)
- Create a specification for a propulsion subsystem that adequately defines the subsystem requirements
- Select the optimum propulsion type and system for a specific mission
- Size a propulsion system for a specific mission
- Select key parts of your subsystem from existing off-the-shelf inventories of components
- Create a list of constraints for the use of your propulsion subsystem
- Design a schematic for your propulsion system
- Plan a test and flight campaign for your propulsion system
Textbooks
There is no required textbook, as I have attempted to give you all of the information you need in the lecture.
You may find the following two optional books to be useful if you want additional background material:
- “Spacecraft Propulsion” by Charles D. Brown, AIAA Education Series, Published in 1996
- ISBN 1-56347-128-0)
- https://www.amazon.com/Spacecraft-Propulsion-Education-Charles-Brown/dp/1563471280
- “Rocket Propulsion Elements” by G. Sutton, John Wiley & Sons (New York, NY) published in 1992
- ISBN 0-471-52938-9
- https://www.amazon.com/Rocket-Propulsion-Elements-George-Sutton/dp/1118753658
Required Software
There are no special software requirements for this class, other than a spreadsheet tool (e.g. Excel) and whatever software you will use to make your final presentation.
Student Coursework Requirements
It is expected that each module will take approximately 7–10 hours per week to complete. Here is an approximate breakdown: attending the lecture (approximately 2.5 hours per week) as well as some outside reading, doing the homework assignments (approximately 3 -4 hours per week) and, later in the class, working with team members to develop the final project presentation (3 – 4 hours per week).
This course will consist of the following basic student requirements:
Graded Exams (30% of Final Grade Calculation)
The assessments will consist of a series of 4 exams worth 30% of the course grade. These exams will be taken by the students during the week.
The subjects of the exams will be as follows:
- Propulsion Basics
- Chemical Propulsion
- Electric and Advanced Propulsion
- Feed Systems
If, for some reason, a student is not able to take the exam during the prescribed time period, I will work with the student to facilitate their taking of the exam at a different time.
Homework Assignments (30% of Final Grade Calculation)
Homework problems will be assigned weekly, and are typically due the night before the following lecture, or according to the dates in the Calendar.
Late submissions will be reduced by one letter grade for each week late (no exceptions without prior coordination with the instructors).
Partial credit for answers will be assessed using the following grading elements:
- Each part of question is answered
- Intermediate derivations and calculations are provided
- Answer is technically correct and is clearly indicated
- Answer precision and units are appropriate
Only the first eight homework assignments will be performed by each individual student, so only these eight homework assignments will count towards the final grade. Subsequent homework assignments will be a part of the final project, and will count towards that grade.
Course Project (40% of Final Grade Calculation)
There will be a single cumulative project that will cover 70% of the class grade (“regular” homework being 30%, and the final project being 40%). This project will have an assignment corresponding to each of the 13 modules of the class. The project will be structured as the design of the propulsion system of a hypothetical interplanetary mission. The goal is to allow the students to use what they are learning to develop an optimized subsystem. Each module will have a homework assignment that will be a step in the design/decision process, with the project completed after module 13 of the class. Students will serve the role of propulsion subsystem engineer, making various design decisions and ultimately designing a propulsion subsystem and planning its integration, test, and flight operations. The instructor will serve in the role of project engineer and subject matter expert providing guidance, comments, and assessments for each of the project modules. Students will also have the opportunity to serve as peer reviewers discussing and critiquing the work of other students.
As an example, in Module 1 students will be given the basic delta-V and mission requirements for a mission, and for homework, asked to select and justify a preliminary propulsion subsystem type and select thruster size/number/orientation/etc. They will then be asked to estimate propellant mass for that system. This, and each subsequent homework assignment, will be formally submitted by the student prior to the start of the next Module, but it will be understood that as time goes by, some of these assumptions will change (as happens in “real life”); i.e., the student will not be held to the decisions made after Module 1 for their final project. Module 2 will include a discussion of these initial decisions where each student will be expected to defend/explain their decision process.
At the end of every Module, information learned in class will be used by the students to update their subsystem design and/or re-visit their design decisions as a homework assignment. Homework assignments will also include example problems to verify students are learning as well as to help with this process. For Modules 1 – 9, homework assignments will be performed by each individual student, but after Module 8, when subsystem design details start to be taught (if class size allows), students with similar design decisions may form a few groups to complete future phases of the subsystem design together. Each class module will begin with discussion of the homework, and students will be asked to defend/explain their design decisions. Through Module 10, students will be encouraged to evaluate their selected subsystem design and consider changing to something else. After that, students will stick with the system they selected.
At the end of the class (Module 14) each group will be required to make a presentation of their propulsion subsystem to the class. The groups will be required to prepare/present a PowerPoint presentation, with each team member verbally presenting his/her part of the overall design. Preliminary versions of the PowerPoint presentations will be submitted by the groups starting after Module 10 with updates expected after each Module to ensure a quality product is presented by each team in Module 14. The amount of time given to each student to present will depend on the number of students in the class.
The final Project will represent 40% of the grade. The grade achieved by the entire team for the final project will be applied to each member of the team, unless there are cases where some members of the team clearly did not participate equally. A rubric for the final project will be provided to the class at least one week before the final projects are presented.
Grading Policy
EP uses a +/- grading system (see “Grading System”, Graduate Programs catalog, p. 10).
| Score Range | Letter Grade |
|---|---|
| 100-97 | = A+ |
| 96-93 | = A |
| 92-90 | = A− |
| 89-87 | = B+ |
| 86-83 | = B |
| 82-80 | = B− |
| 79-77 | = C+ |
| 76-73 | = C |
| 72-70 | = C− |
| 69-67 | = D+ |
| 66-63 | = D |
| <63 | = F |
Final grades will be determined by the following weighting:
| Item | % of Grade |
|---|---|
| Exams | 30% |
| Individual Homework Assignments | 30% |
| Course Project | 40% |
Academic Policies
Deadlines for Adding, Dropping and Withdrawing from Courses
Students may add a course up to one week after the start of the term for that particular course. Students may drop courses according to the drop deadlines outlined in the EP academic calendar (https://ep.jhu.edu/student-services/academic-calendar/). Between the 6th week of the class and prior to the final withdrawal deadline, a student may withdraw from a course with a W on their academic record. A record of the course will remain on the academic record with a W appearing in the grade column to indicate that the student registered and withdrew from the course.
Academic Misconduct Policy
All students are required to read, know, and comply with the Johns Hopkins University Krieger School of Arts and Sciences (KSAS) / Whiting School of Engineering (WSE) Procedures for Handling Allegations of Misconduct by Full-Time and Part-Time Graduate Students.
This policy prohibits academic misconduct, including but not limited to the following: cheating or facilitating cheating; plagiarism; reuse of assignments; unauthorized collaboration; alteration of graded assignments; and unfair competition. Course materials (old assignments, texts, or examinations, etc.) should not be shared unless authorized by the course instructor. Any questions related to this policy should be directed to EP’s academic integrity officer at ep-academic-integrity@jhu.edu.
Students with Disabilities - Accommodations and Accessibility
Johns Hopkins University values diversity and inclusion. We are committed to providing welcoming, equitable, and accessible educational experiences for all students. Students with disabilities (including those with psychological conditions, medical conditions and temporary disabilities) can request accommodations for this course by providing an Accommodation Letter issued by Student Disability Services (SDS). Please request accommodations for this course as early as possible to provide time for effective communication and arrangements.
For further information or to start the process of requesting accommodations, please contact Student Disability Services at Engineering for Professionals, ep-disability-svcs@jhu.edu.
Student Conduct Code
The fundamental purpose of the JHU regulation of student conduct is to promote and to protect the health, safety, welfare, property, and rights of all members of the University community as well as to promote the orderly operation of the University and to safeguard its property and facilities. As members of the University community, students accept certain responsibilities which support the educational mission and create an environment in which all students are afforded the same opportunity to succeed academically.
For a full description of the code please visit the following website: https://studentaffairs.jhu.edu/policies-guidelines/student-code/
Classroom Climate
JHU is committed to creating a classroom environment that values the diversity of experiences and perspectives that all students bring. Everyone has the right to be treated with dignity and respect. Fostering an inclusive climate is important. Research and experience show that students who interact with peers who are different from themselves learn new things and experience tangible educational outcomes. At no time in this learning process should someone be singled out or treated unequally on the basis of any seen or unseen part of their identity.
If you have concerns in this course about harassment, discrimination, or any unequal treatment, or if you seek accommodations or resources, please reach out to the course instructor directly. Reporting will never impact your course grade. You may also share concerns with your program chair, the Assistant Dean for Diversity and Inclusion, or the Office of Institutional Equity. In handling reports, people will protect your privacy as much as possible, but faculty and staff are required to officially report information for some cases (e.g. sexual harassment).
Course Auditing
When a student enrolls in an EP course with “audit” status, the student must reach an understanding with the instructor as to what is required to earn the “audit.” If the student does not meet those expectations, the instructor must notify the EP Registration Team [EP-Registration@exchange.johnshopkins.edu] in order for the student to be retroactively dropped or withdrawn from the course (depending on when the "audit" was requested and in accordance with EP registration deadlines). All lecture content will remain accessible to auditing students, but access to all other course material is left to the discretion of the instructor.