VACCO Chief Engineer Joe Cardin presented a paper on the design of a CubeSat High Impulse Propulsion System at the December 2016 JANNAF conference. The CubeSat High Impulse Propulsion System (CHIPS) is currently under development by CU Aerospace in partnership with VACCO Industries. It is intended for use in CubeSat and micro-satellite platforms expected to execute missions involving more than basic orbit maintenance i.e., substantial altitude changes, formation flying and proximity operations such as rendezvous and docking.
The CHIPS design consolidates the primary propulsion system, Attitude Control System (ACS) and propellant storage into a single bolt-on module that is compatible with a wide range of non-toxic, self-pressurizing liquid propellants. The primary propulsion system uses micro-resistojet technology developed by CU Aerospace to superheat the selected propellant before subsequent supersonic expansion through a micro-nozzle optimized for frozen-flow efficiency. A 1U design is estimated to be capable of providing 471 N-s total impulse at ~20 mN thrust using R236fa propellant, resulting in a volumetric impulse of 525 N-s/liter. The Attitude Control System is a cold gas, 4-thruster array to provide roll, pitch, yaw and reverse thrust with a minimum impulse bit of 0.4 mN-s. A high-fidelity, fully-integrated engineering unit was thoroughly tested in cold and warm gas modes on the University of Illinois thrust stand under diverse conditions. Joe Cardin’s paper presents thrust and specific impulse data for the resistojet thruster using two different propellants. Resistojet data include cold and warm gas performance as a function of mass flow rate, plenum pressure, geometry and input power. Currently, the CHIPS prototype is TRL 5 as a result of a Phase II SBIR effort funded by NASA.