Project Overview

Project Kepler is the Imperial College Space Society Rocket Engine Design Project with the objective to manufacture and test the highest thrust to weight ratio rocket engine ever produced. The engine runs on Isopropyl Alcohol (IPA) fuel and Liquid Oxygen (LOx) oxidizer, with a 5:1 oxidizer to fuel ratio, flowing 10 kg/s of propellant. The engine name is Kepler 5010.2 as the team is working on the second concept after creating the original Kepler 5010 design.

Sponsorship Deal

The project got off to a great start before the Autumn term with a manufacturing sponsorship deal with Alloyed, an additive manufacturing company. The deal was a result of presenting the work on the Kepler engine from last year and the guaranteed completion of Project Kepler. As part of the agreement, the team agreed to trial a new material specially designed by Alloyed for high temperature turbomachinery. The change in material requirement led the team to move away from the fuel rich staged combustion cycle design to a gas generator cycle, slightly reducing the specific impulse but allowing for weight savings.

Recruitment and Technical Tasks

The sponsorship deal came at the right time as the project experienced an influx of new members following a successful recruitment drive. The new Chief Engine Designer, Liam, had the responsibility of bringing everyone up to speed on rocket engine design. The commitment shown by everyone allowed the team to start distributing technical tasks to the whole team.

Combustion Chamber Design

The combustion chamber is a part that carried over from the original Kepler 5010 to the Kepler 5010.2. The chamber makes use of two novel concepts to minimize engine mass – cryogenic LOx as the regenerative coolant for the combustion chamber walls and a short, highly conductive copper inner liner to handle the high temperatures. The team has been working on the manufacturing method for the copper liner and settled on metal spinning to produce the liner.

Floating Combustion Chamber Liner and Nozzle

Injector Head Design

With the combustion chamber design finalized, the team progressed onto the design for the injector head. The team simulated a variety of impinging and swirl injector designs and settled on a swirl injector design using centrifugal forces of the rotating IPA fuel to force it outwards through a concentric ring of oxidizer.

Gas Generator Cycle

Whole Engine

The use of a Gas Generator cycle helped simplify the engine design, however, designing a Gas Generator is not a simple task. It is a full rocket engine in its own right and using the knowledge from designing the main combustion chamber and its injector, the team was able to generate a functional model for the gas generator.

Turbine and Pumps Design

The turbine and pumps went through various designs this term. The previous Kepler 5010 design had more space to play with but the new, more compact Gas Generator required a lot of work to redesign these components. The team initially intended to carry over the radial turbine design but given the need to transfer almost 400k kW of power, the gears would have needed a face width of over 10cm, which could not be done in a way that kept the weight low. Therefore, the team realized that a single shaft for both the turbine and pumps was needed, leading to a shift in turbomachinery concept to a two-stage axial turbine.

Whole engine

Overall, the Project Kepler team has made significant progress towards the manufacturing and testing of the highest thrust to weight ratio rocket engine ever produced. The team has overcome various challenges and is working towards the agreed manufacturing deadline in February 2023.

For any queries contact Liam at

Written by Liam Donnelly, published and edited by Ivan Revenga Riesco