Results from a flight-test campaign for a beam director concept that can be used with directed energy laser systems integrated onto aircraft indicated favorable results for an Air Force Research Laboratory (AFRL) program. According to the AFRL, tests showed the efficacy of various aerodynamic flow control techniques in mitigating optical and mechanical distortions imparted onto a laser beam leaving an airborne platform traveling at high speeds. The AFRL’s Hybrid Aero-Effect Reducing Design with Realistic Optical Components (HARDROC) team, with prime contractor MZA Associates, developed and tested the low-power, subscale beam director. Advanced flow-control techniques were at the heart of the HARDROC program, and tying the aerodynamic modifications to realistic optical components was crucial to demonstrating overall system effectiveness. According to Rudy Johnson, HARDROC program manager, these sensitive optical components are required for an advanced directed energy system. The program, Johnson said, emphatically determined that the effective flow-control techniques could be used with the necessary optical components. The flow-control at the heart of HARDROC has been in development for several years by researchers at AFRL. According to Scott Sherer, Computational Fluid Dynamics (CFD) lead for the HARDROC program, the test team used advanced CFD simulation techniques to demonstrate which flow-control techniques could work and were worth pursuing, and which techniques were not. A test aircraft carries the subscale HARDROC beam director illuminated by a low-power scoring laser during an experimentation flight last year. The HARDROC program evaluated in flight the ability of various aerodynamic flow-control techniques to mitigate optical and mechanical distortions imparted on a laser beam leaving an airborne platform traveling at high speeds. Courtesy of AFRL. AFRL contracted with MZA Associates to design the subscale system that could be either used in a wind tunnel or on an aircraft. The design was ground-tested in an environmental chamber as well as a wind tunnel to ensure functionality and performance under load before culminating in flight testing on a business jet last year. During these flight tests, the aircraft cruised at high speed, and a variety of sensors were used to measure aerodynamic disturbances. The data ultimately demonstrated that the HARDROC beam director enlarges the envelope that airborne directed energy systems can operate in, providing a 360° field of regard across extended speed regimes with reduced size, weight, and power (SWAP) compared to other state-of-the-art turrets. Mike Stanek, technical adviser for the Aerospace Systems Directorate’s Integrated Systems Branch, said the successful flight demonstration of the HARDROC turret clears one key remaining technological hurdle for the operation of high-energy lasers on high-speed aircraft, which could support a variety of Air Force missions. “Integration of the low-SWAP HARDROC turret would allow less laser power to be lost to aero-effects, thus enabling mission performance compared to other types of integration strategies,” Stanek said. The data collected from tests will now support forthcoming airborne beam director development efforts, said Matthew Kemnetz, co-principal investigator for aero-effects and beam control in AFRL’s Directed Energy Directorate at Kirtland Air Force Base.
