Introducing Aphelion Motors
So who is Aphelion Motors? And what are we doing? Aphelion Motors is currently a small group of three friends from Rutgers University who are devoted to space exploration. Two of us are within the School of Engineering and the other is in the Department of Computer Science. We are focused on designing software that will be useful for rocket engine hobbyists and amateurs alike.
As of right now, we are developing Motorsynth, a program that will streamline the design of solid rocket motors (SRMs) in an intuitive user interface. If you are reading this then I am sure you have already heard “it is too dangerous” or “maybe you should stick to only launching model rockets first” with little to no instructions of what to do afterward. The main objective of this program is to not only help inexperienced beginners but also help experienced hobbyists to arrive at their design without having to deal with various different software like MATLAB, Excel, and some random Java programs you found online.
So how exactly is Motorsynth going to help you design your SRM? Well, you can think of Motorsynth as being a suite of programs that may have been previously created but are not sufficient by themselves or just not available to the general rocketry public. Since Motorsynth is a software that is meant to connect and replace various different software, unless you already know the input parameters, its computation begins by importing Propellant Evaluation Programs’ (PROPEP) or Chemical Equilibrium with Applications’ (CEA) combustion outputs — chamber temperature, specific heat ratio, molecular weight, specific impulse, and c-star — and uses them for calculating the SRM parameters that are necessary for further calculations such as the diameter of the nozzle exit or the exit velocity of the exhaust gases.
Afterward, to bring the nozzle into reality, Motorsynth utilizes a numerical method known as the axisymmetric Method of Characteristics which will produce the nozzle contour with the predicted SRM parameters. Next, to make sure the nozzle doesn’t melt like butter when a static firing occurs, the convective heat transfer coefficient is calculated to give a quantitative indication of the heat transfer occurring from the exhaust gases to the nozzle. This can then be plugged into ANSYS’s CFD FLUENT to obtain the convective heat transfer occurring. A quantitative amount of ablative material can then be predicted to be placed on the inner walls of the SRM. Lastly, a proper amount of wall thickness for the SRM will be calculated in order to prevent any failure from the inner pressure loads.
Motorsynth has been in development for a few months now and was created out of the sheer necessity for a program that could condense all of our knowledge and be streamlined for very fast design and therefore production. While it is our first project, it is just the beginning since designing an SRM requires a lot more than just the physics behind its desired performance. Apparatuses like a Crawford strand burner and T-burner are a necessity for obtaining empirical data like the SRM’s burn rate and determining if its combustion will be unstable. These too will require software so they can be designed correctly and most importantly, safely.
We are working to develop a feature-rich, all in one, design program for solid motors that the rocket community can enjoy and hopefully, down the line, we will dabble with liquid rocket engines!