Modeling the Characteristics of Propulsion Systems Providing Less Than 10N Thrust

Although well developed models are available for space lift or orbit insertion levels of thrust, few models, if any, exist for designing propulsion systems for micro- or nanosats or for attitude control, orbit maintenance, or deep space applications. Models predicting the required electrical power, Isp, efficiency, and mass distribution (thruster, propellant, tanks, PPU) of Hall thrusters, ion engines, arcjets, resistojets, electrosprays, monopropellant thrusters, cold gas thrusters, and PPTs given required thrust and delta V will be created from historical data.
These models will then be used to analyze existing propulsion options and key areas of future development.

Specifications from existing thrusters are used to create a database from which best fit curves can be found between different system characteristics. The resulting equations are used to calculate estimated required electrical power, Isp, efficiency, thruster mass, and minimum propellant tank pressure. Propellant mass is then calculated from the rocket equation. The estimated propellant tank mass is calculated by optimizing the equations for thin walled pressure vessels for mass using the minimum propellant tank pressure, propellant mass, and assumptions about tank material and propellant particular to the type of propulsion. PPU mass is estimated from the required power assuming quality solar panels, and a margin is added for lines and fittings.

Models have been successfully created and implemented for Hall, cold gas, monopropellant, and electrospray thrusters.