storms, major frontal weather movements, and related natural phenomena. Based on finalization of the ARC system configuration in FY 1981, the facility will formally transition to the Navy in late FY 1982.

b. Nonacoustic Antisubmarine Warfare. The acoustic detection

of submarines is well advanced. Because its potential has nearly been met and any additional significant advances can be expected to be expensive and difficult to implement, alternative nonacoustic approaches to submarine detection must be systematically studied. These high-risk, innovative approaches must define and address areas of long range promise and assess the vulnerability of our own units to comparable counterdetection measures. The Nonacoustic Antisubmarine Warfare program is an all

encompassing research effort to explore the potential of submarine detection based on observed changes in the ocean environment caused by the submarine's presence. As the name implies, the program complements acoustic detection methods and includes techniques that do not depend on active sonar transmissions or passive acoustic emissions from the submarine. Successful nonacoustic detection techniques will require a full understanding of the ambient ocean environment as well as an assessment of submarineinduced observables. An examination of potential observables useful for detection is under way, and two highly promising sensor techniques have been transferred to the Navy.

In FY 1980, all previous related DARPA work was transferred to the Navy for future independent development. DARPA continues to take the lead in developing airborne sensors to detect the submarine hull. A laser hull detection model was developed and efforts are now under way to expand the model to consider other observables. Special survey instruments are being built to allow a scan of ocean optical properties in conjunction with routine hydrographic studies to characterize the background environment. By mid-FY 1982, the technical assessment will be complete and a capability demonstration program will be defined. The DARPA work is directly coordinated with the larger Navy nonacoustic efforts; program results are transitioned directly.

C. Remotely Guided Autonomous Lightweight (REGAL) Torpedo. REGAL is a technology base program to develop, evaluate, and demonstrate

the technological feasibility of advanced guidance and acoustic sensor concepts that will significantly improve the target acquisition range of advanced lightweight torpedoes. The REGAL torpedo is an antisubmarine warfare weapon that integrates into a single weapon system an acoustic array and advanced signal processing. Upon water entry, the acoustic array and the torpedo separate, with the array descending to a preset depth while the torpedo conducts a slow speed target search.

Successful development of the REGAL technology base will

provide the basis for demonstrating autonomous guidance of the torpedo by means of a communications link to a sensitive acoustic array. This will enable longer detection, acquisition, and track ranges.

An initial REGAL development effort, emphasizing subsystem feasibility and design, produced a prototype that was tested during FY 1980 to evaluate the performance of the guidance and control software. A series of fully autonomous sea runs are being conducted during FY 1981 to evaluate REGAL performance as a function of sensor-target-torpedo geometry, weapon speed and maneuver, target range for handover from stationary to torpedo on-board sensors, and target signal-to-noise ratio. The FY 1982 program will continue to be heavily sea-test oriented, with sea runs becoming progressively more complex as target dynamics are introduced along with the integration of the newly developed brassboard sensor. The final demonstration test series, when completed in FY 1983, will demonstrate the integrated technology base that is necessary for a lightweight torpedo. The REGAL technology base, which is very closely coordinated with ongoing Navy advanced lightweight torpedo and antisubmarine warfare standoff weapon development, will transition to the Navy at the end of FY 1983.

d. Ocean Tactical Targeting (OTT). The OTT program uses advanced processing and communication technology bases to focus on an area of tactical interest and to develop a scene description of sufficient accuracy, resolution, and completeness to support targeting decisions by the local commander. The OTT concept is based on a multisensor data fusion center that combines raw, intermediate, and output level data from broad .area ocean surveillance sensors. It generates geographic, parametric sensor cues to obtain further information. An advanced signal processing capability within each broad area sensor responds to cueing and feedback infor

mation from the fusion center. Successful technology base development of the OTT concept will result in the ability to accurately locate and identify all platforms in a specified area of tactical interest through the exclusive use of broad area ocean surveillance sensors. This unique approach will maximize the use of existing sensor systems without interfering with their basic missions. At the same time, it will demonstrate a fundamentally new technique of designing future sensors.

Initial research tasks in database management have been

completed along with the objectives, schedule, and support (ship, communications, facilities) arrangements for an experiment. This experiment will provide for a limited demonstration of OTT and will stress the collection of data for FY 1982 analysis and evaluation. Subsequent efforts will be on the design and development of prototype fusion center real-time operation and adaptive sensor signal processing, culminating in a major fleet demonstration in FY 1984. The OTT technology base, which is a joint DARPA/ NAVELEX program, is planned for transition to the Navy by FY 1985. B. AIR VEHICLES AND WEAPONS

1. EEMIT or Demonstration Programs

a. Forward Swept Wing (FSW). A manned FSW aircraft made possible with an advanced composite structure and a digital fly-by-wire flight control system will be designed, fabricated, and flight tested to investigate and quantify the aerodynamic characteristics and performance capabilities of this integrated advanced technology vehicle. The program has the potential to achieve major technological breakthroughs in the areas of structures, aerodynamics, stability and control, and configurational design freedom. The flight test will develop confidence in numerous individual technologies, make them viable design options for advanced flight vehicles, and reduce the risk and time associated with their future application.

This program has been structured to demonstrate that advanced composite structures can solve the aeroelastic divergence phenomenon, a static structural instability experienced by forward but not aft swept wings. By solving the divergence problem, a thorough investigation and exploitation of the benefits long attributed to the forward swept wing configuration will be possible, stressing improved maneuverability, low

speed and high angle of attack performance, and the considerable design

flexibility.

Completion of the program through flight test will ensure a credible audit trail from theoretical analysis through design, fabrication, and test, which will enable rapid maturation and acceptance of the pertinent technologies.

Analysis indicates that an FSW tactical aircraft could be as much as 25 to 30 percent lighter than an equivalent aft-swept aircraft or have equivalent range/payload performance improvements. The excellent lowspeed stability and control characteristics, higher lift capabilities of the FSW design and enhanced transonic performance available without transonic drag penalties all promise revolutionary capabilities where runway denial is an operational concern or for operation from small ships.

The foundation of the FSW program is based on two decades of composite material research and exploratory development, with special emphasis on the analysis and design techniques developed by the Air Force to aeroelastically tailor wing structures. NASA airfoil design analysis tools were used extensively in the supercritical airfoil designs along with numerical techniques of the inviscid flow model used to determine. aircraft structural load distributions. The aerodynamic and structural design techniques developed for the NASA/Air Force high maneuverability aircraft technology (HIMAT) program were also used for FSW analysis. The results of 10 years of Air Force, Navy, NASA, and industry digital flight control design programs are integrated into the proposed FSW flight control system. Conceptual studies, design analyses, and wind tunnel testing have shown that excellent low-speed handling qualities and short takeoff and landing capabilities, attributed to the configuration for years, are indeed possible. Wind tunnel tests have also documented increased aerodynamic efficiency through improved lift characteristics and reduced drag levels. Large-scale aeroelastically tailored composite wings that were designed, fabricated, and tested have demonstrated conclusively the ability to solve the aerodynamic structural divergence problem. Successful analysis, design, and test of a flight control system with a man-in-the-loop simulation have demonstrated the capability to control the high static instability in the FSW configuration. Final design will be completed and fabrication started during FY 1981, continued through FY 1982, and cul

minate in a flight test in late FY 1983. A joint DARPA/NASA flight test is planned with further transition of data to the Services following flight

test.

b. X-Wing. The X-Wing is a major innovation in vertical takeoff and landing (VTOL) aircraft design which, by stopping the rotor in flight, combines the vertical lift efficiency of a helicopter with the speed, range, and altitude performance of a transonic fixed-wing aircraft. The objective of this effort is to design, fabricate, and flight test a demonstration vehicle of a size representative of an operational aircraft. The unique X-Wing capability is made possible through circulation control, a system by which the lift on each rotor blade can be selectively controlled by varying the momentum flux of air blown through tangential slots along each rotor trailing edge. The X-Wing aircraft uses the circulation control system to produce lift and achieve stability and control of the vehicle during all flight modes, including in-flight stopping/starting of the rotor wing. Design analysis indicates an operational X-Wing vehicle would have approximately three times the range, speed, and altitude performance of a conventional helicopter with equivalent payload lifting capability. Such characteristics would greatly enhance all current VTOL missions and could provide flexible sea-basing and deployment options for the Navy, in addition to providing new capabilities for all the Services. The X-Wing VTOL initiative was derived from the circulation

control rotor work performed earlier by the David Taylor Naval Ship Research and Development Center. It also takes advantage of advanced stopped rotor dynamics and control work done by the Army in the late 1960s. The Navy is using a 49-ft diameter circulation rotor concept in a current flight test program on the UH-2D helicopter to demonstrate improved reliability, maintainability, and active vibration suppression. Also, the wing of an A-6 aircraft was modified by the Navy to demonstrate circulation control for short takeoff and landing performance improvement and completed a very successful flight test program, during which minimum landing speeds were reduced from 120 knots to 75 knots. The X-Wing program will demonstrate the synergistic impact of basic advances achieved in diverse areas such as advanced composite materials, forward swept wing aerodynamics, and