Combustion Stability in Small Thrusters

Period of Performance: 05/30/2006 - 11/13/2008


Phase 2 SBIR

Recipient Firm

Robert Heffley Engineering
349 First Street
Los Altos, CA 94022
Principal Investigator


The Phase I of this effort encompassed extensive data review and preliminary analysis to define the instability in the subject class of thrusters, identify key factors contributing to the unstable behavior, and outline a plan for the resolution of instability. These key factors were identified as: Mon level in the oxidizer, propellant temperature, and the thruster start conditions. The Phase I effort concluded that the cavity, chamber, and combustion models must be improved to reliably predict stability; an accurate simulation of the thruster start conditions on the flight vehicle is required to have confidence in the stability predictions; both injector and cavity changes must be investigated to ensure problem resolution; and that hot fire testing is required for a high confidence solution. This program will provide the stability model development and the simulation of the start transient conditions for altitude operation. These models will be verified against existing test data. In addition test article designs will be generated and test hardware will be built. Detail test plans and procedures will be drafted and a trade study will be conducted to select the optimum test site. Actual testing is deferred to a future activity associated with this program.