Rogers Aeroscience is pleased to announce that new free technical report downloads have been added to the RASAero aerodynamic analysis and flight simulation software website.  The new free technical report downloads which have been added are:

1. Performance Analysis of the Ideal Rocket Motor.
2. Departures from Ideal Performance for Conical Nozzles and Bell Nozzles, Straight-Cut Throats and Rounded Throats.
3. Erosive Burning Design Criteria for High Power and Experimental/Amateur Solid Rocket Motors.

These new free technical report downloads can be found on the RASAero web site in the Technical Report Downloads - Solid Rocket Motor section.

Additional new material has also been added to the RASAero web site, including a 25 rocket altitude prediction comparison study using barometric altimeter and optical tracking flight data, where 80% of the RASAero flight simulation altitude predictions were within +/- 10% of the flight data, and 40% of the altitude predictions were within +/- 5% of the flight data.

An additional new example rocket run on the RASAero software has also been added, with comparisons with Blacksky AltAcc on-board measured axial acceleration, acceleration-based velocity and altitude, and barometric pressure-based barometric altimeter altitude, from launch through apogee, including a discussion of which portions of the flight the axial accelerometer-based data is considered more accurate, and which portions of the flight the barometric pressure-based barometric altimeter data is considered more accurate.  Also included is a comparison of the RASAero flight simulation prediction for the parachute descent compared to the on-board measured barometric altimeter data versus time.  The RASAero flight simulation prediction for the parachute descent time has a less than 10% error compared to the barometric altimeter flight data.

The Performance Analysis of the Ideal Rocket Motor is one of the best textbook chapters ever written covering the derivation of the ideal rocket motor thrust equation.  The full derivation of the ideal rocket motor thrust equation, specific impulse, characteristic velocity, nozzle exit pressure as a function of nozzle expansion ratio, all are covered in extensive detail.

Departures from Ideal Performance for Conical Nozzles and Bell Nozzles, Straight-Cut Throats and Rounded Throats, provides extensive information on correcting the ideal thrust coefficient and the theoretical specific impulse to the actual thrust coefficient and the delivered specific impulse, using the thrust coefficient and characteristic velocity efficiency factors.  For the first time to the author's knowledge, thrust coefficient losses from using straight-cut throats for high power and experimental/amateur/Tripoli Research solid rocket motors are quantified.

Erosive Burning Design Criteria for High Power and Experimental/Amateur Solid Rocket Motors presents easy to use design criteria to determine the maximum length-to-diameter (L/D) ratio for a motor design, or the minimum diameter for the motor core to maximize propellant loading, for either non-erosive burning or maximum recommended erosive burning.  The author proposes a unique approach of using combined core Mach number/core mass flux erosive burning design criteria, design criteria which are applicable whether the motor propellant is sensitive to velocity-based or mass flux-based erosive burning.  An innovative constant core mass flux core design is proposed by the author that maximizes the L/D of a motor design, or minimizes the motor port area (core cross-sectional area) for maximum propellant loading.

The RASAero authors are always looking for flight data to compare our altitude predictions against to help further improve the accuracy of our flight simulations.  The flight data and rocket information can be sent to the e-mail address below.

Additional information on the RASAero software can be found on the RASAero web site at www.rasaero.com.  The RASAero authors, Charles E. (Chuck) Rogers and David (Coop) Cooper can be contacted at This email address is being protected from spam bots, you need Javascript enabled to view it .

Chuck Rogers
Rogers Aeroscience