A direct measurement torsional thrust balance for electric thrusters has been developed to test pulsed plasma thrusters (PPTs) and other electric thrusters. The current configuration is able to measure impulse bits between 14 and 79 μN • s with a resolution of 0.05 to 0.10 μN • s. The direct measurement technique, in which the thruster is mounted on the thrust balance, is considered the most suitable and accurate for applications with PPTs. The use of flexural pivots with low stiffness makes the balance compact, with a smaller torsional arm. An electrostatic calibration device (ECD) was designed and built to calibrate the thrust balance, simulate the thrust of PPTs, and to allow forthcoming tests of the double discharge pulsed plasma thrusters developed at the Associated Laboratory of Combustion and Propulsion of the Brazilian National Institute for Space Research at the Electric Space Propulsion Laboratory. The maximum impulse bit measurement error achieved was as low as 10%, lower than the average of 12%-15%, typical for this type of thrust balance. The ECD was calibrated using a previously calibrated precision analytic scale. The ECD then can carry this calibration traceability to the thrust balance, providing a higher level of accuracy.

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Pulsed Plasma Thrusters (PPTs) are long standing electric propulsion thrusters that are reliable, relatively simple and low cost. One of the main issues with PPTs is its low efficiency (discharge energy vs. exhaust jet"s kinetic energy), typically between 3-8%. One of the main contributors for the low performance in PPTs is the late time ablation (LTA). LTA is the sublimation of propellant that takes place after the main discharge, due to the propellant, usually Teflon ® , temperature being above its sublimation point. The LTA produces a low speed gas and macro particles that does not contribute significantly to produce thrust. The High Frequency Pulsed Plasma Thruster (HFB-PPT) is a novel patented design that aims at accelerating the late time ablation by employing additional discharges after the main discharge. This paper presents the HFB-PPT concept and preliminary results.

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Hybrid rockets using green propellants have been considered for launching nanosats into low Earth orbit (LEO). This work determines the preliminary mass distribution and sizing of hybrid rockets using 98 % H 2 O 2 and solid paraffin mixed with aluminum as propellants.An iterative process is used to calculate the rocket performance characteristics and to determine the inert mass fraction from given initial conditions. It is considered a mission to place a 20 kg payload into a 300 km circular equatorial orbit by air launched and ground launched hybrid rockets.