Scott Snyder

Differential GPS/inertial navigation approach/landing flight test results

In November of 1990 a joint Honeywell/NASA-Langley differential GPS/inertial flight test was conducted at Wallops Island, Virginia. The test objective was to acquire a system performance database and demonstrate automatic landing using an integrated differential GPS/INS (Global Positioning System/inertial navigation system) with barometric and radar altimeters. The flight test effort exceeded program objectives with over 120 landings, 36 of which were fully automatic differential GPS/inertial landings. Flight test results obtained from post-flight data analysis are discussed. These results include characteristics of differential GPS/inertial error, using the Wallops Island Laser Tracker as a reference. Data on the magnitude of the differential corrections and vertical channel performance with and without radar altimeter augmentation are provided.<<ETX>>In November 1990, a differential GPS/inertial flight test was conducted to acquire a system performance database and demonstrate automatic landing using an integrated differential GPS/INS with barometric and radar altimeters. Flight test results obtained from postflight data analysis are presented. These results include characteristics of DGPS/inertial error, using a laser tracker as a reference. In addition, data are provided on the magnitude of the differential correlations and vertical channel performance with and without radar altimeter augmentation. Flight test results show one sigma DGPS/inertial horizontal errors of 9 ft and one sigma DGPS inertial vertical errors of 15 ft. Without selective availability effects, the differential corrections are less than 10 ft and are dominated by receiver unique errors over the time period of an approach. Therefore, the one sigma performance of the autonomous GPS (8-ft horizontal and 20-ft vertical) is very similar to the DGPS/inertial performance. Postprocessed results also demonstrate significant improvements in vertical channel performance when GPS/inertial is aided with radar altimeter along with a low-resolution terrain map.<<ETX>>

INS/GPS operational concept demonstration (OCD) high gear program

On February 10, 1993 an Air Force F-16 dropped an INS/GPS modified GBU-15 from an altitude of 35,000 feet and a downrange distance of 88,000 feet in adverse weather. The guided weapon impacted within 6 meters of the target, demonstrating the potential of INS/GPS technology to significantly improve air-to-surface munitions strategies and tactics. This landmark flight was successfully followed by five additional drops with varying attitudes, downrange distances and weather conditions. OCD was designated an Air Force High Gear program, allowing streamlined acquisition and reporting procedures, in response to Operation Desert Storm experience highlighting the need for attacking high-value targets from high altitude in adverse weather. OCD met its objective to build and demonstrate an INS/GPS weapon in an operationally representative environment. Results of the demonstration show there is low technical risk associated with development of INS/GPS munitions considered for the Joint Direct Attack Munitions (JDAM) program.<<ETX>>On February 10, 1993 an Air Force F-16 dropped an INS/GPS modified GBU-15 from an altitude of 35000 ft and a down range distance of 88000 ft in adverse weather. The guided weapon impacted within 6 meters of the target, demonstrating the potential of INS/GPS technology to significantly improve air-to-surface munitions strategies and tactics. This landmark flight was successfully followed by 5 additional drops with varying altitudes, downrange distances and weather conditions. OCD was designated an Air Force high gear program, allowing streamlined acquisition and reporting procedures, in response to Operation Desert Storm experience highlighting the need for attacking high-value targets from high altitude in adverse weather. OCD met its objective to build and demonstrate an INS/GPS weapon in an operationally representative environment. Results of the demonstration show there is low technical risk associated with development of INS/GPS munitions considered for the Joint Direct Attack Munitions (JDAM) program. This paper provides additional details on program objectives, system implementation, and test results. The focus of this paper is on the implementation and performance of the integrated INS/GPS navigation system.<<ETX>>

Differential GPS/inertial navigation terminal area guidance flight test results

Terminal area flight test results of a differential GPS (Global Positioning System) inertial navigational system are presented. The flight test was a joint Honeywell/NASA-Langley project completed in November 1990. Over 120 landings were made with the NASA Transport Systems Research Vehicle (TSRV), a specially modified Boeing 737-100, including 36 fully automatic differential GPS/inertial landings. A description of the system implementation and preliminary flight test results are provided.<<ETX>>