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Air Force fine-tuning first laser weapons for aircraft

A test aircraft carries the sub-scale HARDROC beam director illuminated by a low-power scoring laser during an experimentation flight August 12, 2022. 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. [Credit: Photo courtesy AFRL]

 

 

 

 

After Lockheed Martin's first delivery of a high-energy LANCE laser weapon for flight last year, the U.S. Air Force's research team is fine-tuning the workability and flexibility of such a weapon in the unique challenges of combat in the skies.

The U.S. Air Force Research Laboratory (AFRL) recently completed a successful flight-test campaign for a new beam director concept that can be used with directed energy laser systems integrated onto aircraft.

The Hybrid Aero-Effect Reducing Design with Realistic Optical Components, or HARDROC, team, consisting of personnel from AFRL's Aerospace Systems Directorate at Wright-Patterson Air Force Base, Ohio, and Directed Energy Directorate at Kirtland AFB in New Mexico, along with prime contractor MZA Associates, developed and tested a low-power, sub-scale beam director to evaluate 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.

"The HARDROC beam director is a leap forward in technology to minimize aerodynamic degradations," said Rudy Johnson, HARDROC program manager. "This series of flight tests demonstrated the effectiveness of flow control to reduce the aerodynamic effects on the beam director."

The flow control at the heart of HARDROC has been in development for several years by researchers at AFRL.

"Using advanced computational fluid dynamic, or CFD, simulation techniques, we were able to demonstrate significant reduction in aero effects across a wide range of speeds and look angles," said Dr. Scott Sherer, CFD lead for the HARDROC program. "We effectively utilized a substantial amount of computational hours provided by the Department of Defense High Performance Computing Modernization Office to establish which flow-control techniques could work, which techniques were worth pursuing, and which were not."

The Aerospace Systems Directorate team worked closely with their counterparts at the Directed Energy Directorate and leaned on previous efforts in beam director development to further the technology used in the HARDROC Program.

While advanced flow-control techniques were at the heart of the HARDROC Program, tying these aerodynamic modifications in with realistic optical components was crucial to demonstrating overall system effectiveness.

"Based on our computational simulations and wind-tunnel results, we felt very confident the flow control would perform well," said Johnson. "But the biggest question in our mind was whether these flow-control techniques could be used with the sensitive optical components required for an advanced directed energy system. HARDROC answered that question with an emphatic yes."

To get to these answers, AFRL contracted with MZA Associates, a world leader in the modeling, analysis, design, development, integration, and testing of High Energy Laser, or HEL, and advanced optical systems to design a sub-scale system that could be either utilized in a wind tunnel or on an aircraft.

The resulting 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 during the summer and autumn of 2022. During the flight tests, the aircraft cruised at high speed, and a variety of sensors were used to measure aerodynamic disturbances. The data demonstrated that the HARDROC beam director enlarges the envelop that airborne directed energy systems can operate in, providing 360-degree field of regard across extended speed regimes with reduced size, weight, and power, or SWaP, compared to other state-of-the-art turrets.

"The successful flight demonstration of the HARDROC turret clears one of the key remaining technological hurdles for operation of high-power lasers on high-speed aircraft for a variety of Air Force missions," said Dr. Mike Stanek, Technical Advisor for the Aerospace Systems Directorate's Integrated Systems Branch. "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."

The Air Force has not released the power capabilities of all of its laser weapons yet. Lockheed has created a 300-kW weapon for land use for the Department of Defense and is working on a 500-kW version, and systems size and weight are shrinking due to optimized designs. The initial Air Force directed energy laser systems are thought to be much lower in power (<100 kW). System size, weight, and power needs are all considerations for adding to flight.

Raytheon Technologies also delivered a palletized high-energy 10-kW laser, called H4, to protect people and assets against "short-range aerial threats" to the Air Force in June of this year. That system is small enough to fit in the bed of a pickup truck. It was the fourth operational laser weapon system that Raytheon Technologies has delivered to the Air Force and is the eighth total system the company has delivered to the U.S. Department of Defense.

Sources: Air Force Research Laboratory, Lockheed Martin, Breaking Defense

Published October 2023

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