NASA 

National Aeronautics and 

Facts

Space Administration 

Dryden Flight Research Center 

P.O. Box 273

Edwards, California 93523 

Voice 661-276-3449 

FAX 661-276-3566 

pao@dfrc.nasa.gov FS-1998-03-039 DFRC 

Systems Research Aircraft in flight EC 97 44272-6 

F/A-18 Systems Research Aircraft

The NASA Dryden Flight Research Center is using an F/A-18 Hornet fighter aircraft as its Systems 

Research Aircraft (SRA). The aircraft is on loan from the U.S. Navy. 

Background 

The SRA project helps ensure that new aerospace concepts are transferred quickly to the U.S. aerospace 

industry so they can be applied to technologies for commercial and military aircraft and space vehicles. 

Key technologies investigated aboard the F/A-18 SRA include advanced power-by-wire concepts and 

fly-by-light (fiber optic cable) systems, as well as electric-powered actuators and advanced flight-control computer software. In the past, pilots controlled aircraft through direct force. As engine power and speeds increased, 

more force was needed, and hydraulically boosted control, governed by flight-control computers, emerged. 

Power-by-wire, fly-by-light systems and electric-powered actuators aim to eliminate cumbersome hydraulic 

cables in favor of more versatile wires and fiber-optic cables. 
Future aircraft that will benefit from research aboard the SRA are the high-speed civil 

transport

 next-generation general aviation and military 

aircraft. In addition, the program is developing 

advanced

 flight-test techniques that will be used on future 

aircraft. 

Introduction 

The primary goal of the SRA program is to 

identify and flight-test the newest and most advanced 

technologies beneficial to subsonic, supersonic (faster 

than the speed of sound), hypersonic (more than five 

times the speed of sound) and space applications. The 

SRA facility allows government and industry to focus 

the integration, ground test and flight validation of 

breakthrough technologies. 

The ability to flight-test new technologies can 

eliminate perceived and real technical barriers. The 

systems testbed approach used by the SRA facility 

lowers development cost, decreases the time needed to 

develop new technologies and focuses research efforts. 

The program fulfills several goals of NASA 

Aeronautics and Space Transportation Technology, 

including increased aviation safety, improved environmental compatibility and cheaper access to space. 

Flight Research Programs 

Electrically Powered Actuation Design 

Validation Program (EPAD) — The purpose of the 

EPAD program is to examine the reliability and 

performance of advanced actuators. An actuator 

translates signals from the aircraft’s flight controls to a 

mechanical action of control surfaces such as flaps, 

ailerons and rudders. The EPAD program is a joint 

effort by NASA, the U.S. Air Force and U.S. Navy. 

Two actuators, the Smart Actuator and the ElectroHydrostatic Actuator have been tested successfully 

aboard the SRA. The third actuator in the program, the 

Electro-Mechanical Actuator, arrived at Dryden in 

October 1997. The Electro-Mechanical Actuator could 

significantly reduce the costs and logistical and maintenance support for future aircraft by helping eliminate 

sophisticated but heavy aircraft hydraulic systems in 

favor of electrical “power-by-wire” systems for 

operating flight controls. Besides savings in cost and 

support, electrical systems promise diminished vulnerability in combat by eliminating hydraulic lines in the 

fuselage and wing box. The experiment is slated to 

begin flight-research missions in March 1998 after 

ground-based testing.

 Schlieren Imaging System Experiment — 

The Schlieren Imaging System experiment uses two F18s, one “chase” aircraft outfitted with a special 

airborne camera system and Dryden’s F/A-18 SRA, 

which acts as a “target” aircraft. As the F/A-18 SRA 

passes at supersonic speeds in front of the sun, its 

shock waves, which are more dense than the surrounding air, are illuminated. The F/A-18 with the Schlieren 

Imaging System can record these shock waves using 

the system’s optics and imaging camera that are 

located in a modified NITE Hawk Forward Looking 

Infrared pod. This pod provides the stability and 

tracking required for Schlieren imaging. Studying 

images of shock waves has several potential applications: allowing researchers to reduce the effects of 

sonic booms on the ground, verifying and enhancing 

wind tunnel studies and computational techniques that 

predict the structure and movement of shock waves 

and observing the interactions of aircraft engine 

exhaust/plume shocks that can have a negative impact 

on engine acoustics or performance. Imaging flights 

are scheduled to begin in early 1998.

 Air-to-Air Global Positioning System — To 

perform the carefully choreographed Schlieren experiment, the F/A-18 SRA and Dryden’s F-18 no. 846 will 

use a new air-to-air global positioning system (GPS). 

The air-to-air GPS system consists of a GPS receiver 

and modem in each aircraft for data communications 

between the F-18s. F-18 No. 846, the “chase” aircraft, 

processes information in its receiver, calculates the 

real-time relative positions of the two aircraft, and 

displays these positions for the pilot. This provides 

precise information about the position of the SRA 

“target” aircraft, which is necessary for the Schlieren 

imaging. Air-to-air GPS also has valuable applications 

where precise information about the relative positions 

of aircraft might be necessary. Possible uses include 

close formation flight and vortex flow surveys behind 
aircraft. Early flight-research missions have shown 

accuracy of within 6 inches. 

Production Support Flight Control Computer—The Production Support Flight Control Computer is slated to speed up the development of new 

flight-control software. Standard F-18s fly with one 

set of flight-control software. This new system allows 

the aircraft to fly using two sets of software — research flight-control software and the standard flightcontrol software. The aircraft will be able to fly using 

the research software, and if problems occur, the pilot 

will be able to quickly switch over to the standard 

flight-control software. This new capability will speed 

up the development time for new flight-control software by shortening the amount of validation and 

verification time spent on the ground before it is 

installed and flown on the aircraft. The Production 

Support Flight Control Computer underwent a combined systems test in December 1997, and is scheduled to fly in March 1998. 

Program Management 

Dryden’s Systems Research Aircraft program 

is a joint effort between Dryden and NASA’s Langley 

and Lewis Research Centers. Also participating are the 

U.S. Air Force and Navy.

The SRA has been developed from a preproduction model of the F/A-18, a two-seat fighter/ 

attack aircraft built by Boeing, formerly McDonnell 

Aircraft Co., St. Louis, Mo. The F/A-18 is currently in 

service with the U.S. Navy and Marine Corps. 

Aircraft Specifications 

The aircraft has a wing span of 40 feet five 

inches The fuselage is 56 feet long and 10 feet six 

inches high at the canopy. 

The SRA is powered by two General Electric 

F-404-GE-400 turbofan engines, each producing 

16,000 pounds of thrust in afterburner. 

Typical takeoff weight of the SRA is 39,000 

lb, with 10,000 pounds of internal fuel. 

March 1998 

Three view of F/A-18 Systems Research Aircraft