Rasp XP 3.0

Rasp XP v3.0 – Rocket Altitude Simulation Program for Windows

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Rasp XP Technical Information

Rasp XP is a Windows program that simulates the flight of a rocket in one dimension (one degree-of-freedom). It can be used to get an idea of how high a rocket kit might fly with a particular motor and what the best ejection delay time might be. Rasp XP is an adaption of the venerable RASP program for DOS that was based on the BASIC program by Harry Stine in 1979 from “Handbook of Model Rocketry”. It was converted to C by Mark Storin in 1989. New features were added by Kent Hoult in 1990 and Mark Johnson in 1990-94.

Rasp XP v3.0 includes Larry Curcio’s DigiTrak, based on his version 5.4.

Rasp XP Data Files

Though the Rasp XP program itself does not change very often, the data files that Rasp XP uses are based on current motors and kits. These files are just text files and the Rasp XP help files contain information about how to change them. However, most rocket folks are reluctant to do that. The active rocketeers are interested in the most current motor data – especially when a batch of new motors are tested and declared certified by TRA or the NAR.

There are several places to obtain the thrust curves, assemble the data, and merge the results into a wRASP data file. The recommended location is ThrustCurve.org as they are very good at maintaining a complete and up-to-date collection of motor data files.

Previous Version Notes

Rev 2.1BW
This was an interim release for Dallas Area Rocket Society (DARS).


  • NAR tracking equations solver – equations from the “Pink Book” tracking system. Includes the four test cases in case some thinks the software has gone bad during a contest launch;
  • The ability to “associate” a *.RSP file and launch wRASP by double-clicking the *.RSP file and load that file in the process. For Windows 3.1, this association can be done manually through Program Manager. For Windows 95, the necessary registry entries are set during the installation process. This can be done manually, also, if needed.

Rev 2.1
This is a not-quite-complete (documentation lagging) update just because it has been a long time since all of the files were updated.


  • Updated the motor data loader (fixed some bugs);
  • Added the NAR-certified motor data from NAR S&T curves;
  • New rocket kit (rocket.dat and vendor.dat) database files.

NOTE on motor database file limitations:

  • DOS RASP89 and versions of wRASP through v1.6 had a limit of 32 data points per curve – time plus thrust or 64 total values;
  • wRASP v1.61 changed the thrust curve storage method but left in (erroneously) the 64 value limit so that individual curves could have up to 64 points. This was retained through wRASP v2.1BW;
  • wRASP v2.1- (and subsequent) eliminated the 64 point limit and only limits the total number of points in the ENTIRE DATABASE to 16384. This was a result of building the NAR certified list which has several motors with more than 64 data points.

PLEASE NOTE that the NAR motor database WILL NOT run on any version of wRASP prior to version 2.1