Data Acquisition and Control Software for FALCON Rocket Motor Testing

AirLaunch LLC, Kirkland, WA, worked on the development of the QuickReach (TM) small satellite launcher as part of the U.S. Air Force/DARPA FALCON program during the '00s.  This launcher was to have been a two-stage, vapor pressure-fed, LOx/Propane vehicle which had the unique attribute of being air-launched from a C-17 cargo aircraft.  Further information on this program can be found at the Air Launch web site, and in a comprehensive article in the Oct. 24, 2005, issue of Aviation Week & Space Technology.

In 2005 and 2006, Orion Propulsion, Inc., Madison, AL, developed two rocket motor test stands to support testing of the second stage engine at the AirLaunch test site in Mojave, CA.  These stands are the Horizontal Test Stand (HTS) and Vertical Test Stand (VTS) and allow engine testing in horizontal and vertical configurations, respectively.  The photos at right show typical motor hot firing tests on the stands at the Mojave site. 

BML developed data acquisition and control software programs for each of the two test stands.  A common feature of both programs is the ability to remotely control actuators on the test stand and to acquire and record data from test stand sensors. Both programs were written using LabVIEW.  Specific capabilities of the two programs are presented below.

Horizontal Test Stand Software
The HTS software was used to perform two tasks: 1) propellant management prior to and following hot firing tests; and, 2) engine control during hot firings.  The propellant management task involved propellant tank loading and discharging; and, pre-test conditioning of the propellants to achieve desired propellant temperatures and pressures.  The actions required to perform these functions were controlled manually by the Test Conductor.

The second task of the HTS software is engine control during a hot firing.  The functions performed automatically by the software during a hot firing were:

1) igniter start;
2) main engine combustor start;
3) steady state operation; and,
4) engine shutdown.

Ancillary functions of the HTS software included remote control of the fire extinguisher system and still cameras.

Vertical Test Stand Software
Relative to the HTS software, BML's VTS software performed an expanded propellant management task and, due to the use of a flight-representative engine control system for VTS testing, a much-reduced engine control task.

The expansion of the propellant management task was due to the increased number of actuators and sensors on the VTS relative to the HTS.  In addition, for more precise control of the tank pressures, the VTS software featured closed-loop control of the pressure in both propellant tanks.

The engine control task of the BML VTS software was limited to providing the capability for the Test Conductor to manually terminate a test by overriding the flight-representative engine controller.

Ancillary functions of the VTS software included the remote control of the fire extinguisher, still camera, flame bucket and noise suppression system.

Other Support for FALCON
In addition to the data acquisition and control system software, BML also provided the following support to the FALCON motor test program:

• developed the data acquisition and control system electronic hardware, in cooperation primarily with Orion Propulsion
• Mr. Bergmans performed the role of Test Conductor for several hot firings on the HTS
• provided training to other Test Conductors on the use of the HTS and VTS software
• performed test data reduction and analysis
• participated in development of written test procedures for operation of both stands