A hybrid rocket motor is a complex rocket engine that uses two phases of reactants, a solid fuel and a gaseous/liquid oxidizer, to produce powerful, efficient propulsion.


Our first generation hybrid rocket engine, GORE Mk.1, reacts gaseous N2O and O2 at 800 psi with paraffin wax as fuel. N2O is a non-toxic gas which does not ignite spontaneously under normal conditions. It may intensify fires, so to preserve safety, we use it in a controlled, well-ventilated environment at all times. The paraffin wax we use is similar in composition to candle wax and is safe to handle. We chose these propellants according to various criteria including, but not limited to, price, spontaneity, safety, and availability of documentation.

We used NASA-sponsored Rocket Propulsion Analysis software to predict the theoretical behavior of our engine. After conducting thermal analysis of the engine, we decided to coat the inside of Mk.1’s combustion chamber with a layer of zirconium oxide.

GORE Mk.1 is the most powerful hybrid motor produced by the University of Illinois with a total impulse output of 3400 lbf*s (15,000 N*s) and a maximum thrust output of 1250 lbf (5.5 kN). We are aiming for a 4 second engine fire.

Cold flow tests during the the 2015-2016 year were successful and hot fire tests in the summer of 2016 have proven successful as well. More testing will be conducted into the 2016-2017 school year. Video of our engine testing can be found in the Gallery section of this website. 


Our second generation hybrid rocket engine, GORE Mk.2, was designed with over 1,350 lbf (6 kN) of thrust and a burn time of 30 seconds, fueled by liquid N2O and solid paraffin wax. The engine was designed to be 3D printed out of Inconel 718 using DMLS technology.

Due to the high cost associated with building efficient and lightweight hybrid engines at this scale, the the construction of the engine has been deprioritized in our refocus on liquid propulsion systems. Our experience designing Mk.2 will be distilled into technical documentation that will carry the many lessons we learned with this engine on to guide the future propulsion engineers of SSS.


Our move to liquid engines is about more than just choosing a sustainable, powerful technology. We also view liquid propulsion as an opportunity to demonstrate the increasing accessibility of aerospace technology in the world and to emulate the current state of rocket propulsion in industry

Liquid V1

V1 is a LOX/Hydrocarbon engine that will leverage DMLS additive manufacturing technology to be primarily constructed out of Inconel 718. V1 is designed to generate 1,000 lbf (4.4 kN) of thrust and fly on our Phase IV rocket. It will use a thermal barrier coating and is intended to give SSS experience with simpler liquid propulsion systems before advancing our technology for future launch vehicles.

The project is currently approaching final design review and fabrication will begin by Fall 2016, with testing planned for Spring of 2017.

Liquid V2

Liquid V2 will more than double the thrust capabilities of Liquid V1. The engine will feature an electrically driven propulsion cycle, a regeneratively cooled combustion chamber, and thrust vectoring capabilities. Preliminary design for V2 will begin in Spring 2017.