WSL COMMEMORATES 50 YEARS OF SURVIVABILITY LFT&E
By Marty Krammer
The year 2020 marks the 50th year that the Weapons Survivability Laboratory (WSL) at the Naval Air Warfare Center Weapons Division (NAWCWD) in China Lake, CA, has been performing tests and generating data for the survivability community. The results of this half century of work have been incorporated into countless designs to make succeeding generations of air platforms tougher, safer, and more dependable. And many fixed-wing and rotary-wing aircraft flying in the skies today have directly benefited from WSL’s important efforts.
THE HISTORY OF WSL
In 1969, the Naval Air Systems Command (NAVAIR) initiated the Aircraft Survivability Program (ASP) to address survivability issues that had continued to plague combat aircraft from their first use in World War I and II and throughout the Korean and Vietnam conflicts. The primary motivation at the time was to address the unexpectedly high rate of U.S. aircraft losses (more than 5,000) to small arms threats in Southeast Asia, as well as the high number of incidents (more than 30,000) resulting in combat damage. The program’s focus was to conduct research, studies, full-scale experiments, and analysis on aircraft fuel systems, subsystems, and components to determine vulnerability of aircraft and provide solutions for survivability issues.
That same year, NAVAIR selected the Naval Weapons Center (NWC) in China Lake as the lead laboratory to conduct research and development work aimed at understanding vulnerability and survivability of Navy combat aircraft (e.g., the A-4 Skyhawk, F-4 Phantom, F-14 Tomcat, and A-7 Corsair).
In 1970, NWC established the Aircraft Vulnerability/Survivability Gun Range (shown in Figure 1) to address Navy aircraft survivability initiatives. Likewise, the Navy’s first vulnerability live fire test site was completed and went into operation in 1970, first testing the Navy’s A-4 Skyhawk. This testing marked the beginning of the Navy’s history of evaluating the lethality of foreign threats against U.S. aircraft and identifying potential vulnerabilities associated from hits to the aircraft’s fuel system (tanks) and surrounding structure (shown in Figure 2).
Now with a facility dedicated to evaluating aircraft systems, it didn’t take long for NWC engineers involved in A-4 testing to determine that there were limitations with testing capabilities, primarily due to a lack of airflow.
The need for a more realistic test environment thus led to the development of the facility’s first High Velocity Airflow System (HIVAS) in 1975 (see Figure 3). HIVAS provided, and continues to provide, the realism needed for aircraft vulnerability live fire testing by simulating in-flight airflow conditions over aircraft surfaces or engine inlets during testing.
In 1976, under the newly created Survivability and Lethality Division, the Aircraft Survivability Range became its own branch, along with the Analysis Branches, Vulnerability, Susceptibility, and Lethality. Now combining live fire testing and analysis within NWC established a model-test-model approach to identify and test vulnerabilities and make recommendations to improve the survivability of U.S. aircraft and weapon systems. The Aircraft Survivability Range would go on to change its name in 1980 to that of the Weapons Survivability Laboratory to reflect the change that was taking place within the facility in providing a laboratory environment rather than a modest range operation.
THE MANDATE FOR REALISTIC TESTING
Survivability is now an essential and formal part of the U.S. Department of Defense (DoD) acquisition process. In 1991, the DoD 5000 series of directives and instructions for the acquisition of weapons systems defined survivability as a critical system characteristic—that is, a characteristic of the system that has a critical role in the effectiveness of the systems. Accordingly, the Live Fire Law passed in 1987 (Title 10, U.S. Code Section 2366) requires that the Secretary of Defense conduct realistic survivability, lethality, and initial operational testing and evaluation on covered weapons systems before they proceed beyond low-rate initial production. Realistic survivability testing—that is, full-up system-level testing—means testing for the vulnerability of the system in combat by firing at the system those munitions likely to be encountered in combat.
WSL FACILITIES AND CAPABILITIES
The WSL mission has remained consistent through the decades, ensuring the DoD is provided mission-effective survivable air platforms both now and in the future. WSL is the Navy’s field activity for weapons systems nonnuclear survivability, weapons lethality, and Live Fire Test and Evaluation (LFT&E), supporting all of the major Services. WSL excels at live-fire testing of military aircraft against a broad spectrum of threats, including munitions from small arms to antiaircraft artillery (AAA) rounds, rocket-propelled grenades (RPGs), warheads, fragments, and newer emerging threats.
As shown in Figure 4, WSL is located within the boundary of NAWCWD China Lake, in a remote and secure 11-square-mile area. The laboratory is divided into two major physical areas: the test sites and the preparation and administration area. Testing is performed at five primary sites (shown in Figure 5) that can accommodate military aircraft ranging in size from small, unmanned air vehicles to jumbo-sized transports.
Test Sites 1–4 each contain a test area or pad, control room building, data acquisition, fire-fighting capabilities (aqueous film-forming foam [AFFF] and CO2), and fluid waste collection capabilities to support testing operations. Sites 2 and 4 became operational in 1970, and Sites 3 and 1 added in 2003 and 2010, respectively. All of the sites have similar facilities and capabilities but vary in pad size, airflow, and explosive-limit capabilities. Sites 2 and 3 each include dedicated airflow systems (HIVAS and Super HIVAS), while Sites 1 and 3 include an under-the-pad tunnel for firing threats at test articles from below.
Test Site 5 became operational in 2010 to support the development, test, and evaluation of the Hostile Fire Indicator (HFI) system on board helicopters. Evaluating HFI systems within an operating helicopter presents a significant challenge due to obvious safety concerns of firing threat projectiles near a manned helicopter. With that in mind, the HFI facility (Site 5) was developed to enable testing of HFI systems while installed within a remotely operated helicopter. This site provides for firings of threat weapons from 5.45-mm small arms to 40-mm anti-aircraft gun systems, including ball, armor-piercing (AP), armor-piercing incendiary (API), and high-explosive incendiary (HEI) projectiles. In addition, RPGs and other unguided rockets with inert warheads are currently approved for test firings. And more recently, the site’s terrain and capabilities have shown the site to be well-suited for testing smaller, unmanned air vehicle threats.
Because of the cost and safety hazards associated with actual in-flight survivability testing, in-flight airflow conditions are simulated using WSL’s four-engine HIVAS (Site 2), nine-engine Super HIVAS (Site 3), and single-engine Portable HIVAS (shown in Figure 6). Both HIVAS and Super HIVAS systems redirect and combine bypass airflow from multiple turbofan engines into single or dual nozzles to provide speeds of between 40 and 520 knots (Mach 0.82). WSL’s portable HIVAS is similar to the larger systems but uses a single turbofan engine to produce up to 600 knots of airflow. In addition, these HIVAS systems provide the capability to support additional types of testing and analyses, such as aerodynamic studies, ordnance testing of flares and rocket motors, stores ejection and separations, aircraft canopy and seat ejections, windblast, and parachute deployment testing. These capabilities, on a fixed, ground-based test complex with full instrumentation, ultimately reduce research, development, test, and evaluation (RDT&E) costs and allow testing that otherwise would be difficult, if not impossible, to perform.
Survivability tests at WSL range from full-scale U.S. and foreign aircraft and subsystems to smaller-scale develop-mental hardware, simulators, replicas, components, and materials. U.S. aircraft evaluated at the facility since 1970 include the A-4 Skyhawk, A-6 Intruder, A-7 Corsair, AV-8 Harrier, F-86 Sabre, F-89 Scorpion, F-4 Phantom II, F-111 Aardvark, F-14 Tomcat, F-16 Fighting Falcon, F-15 Eagle, F/A-18 Hornet and Super Hornet, F-35 Lightning II, P-3 Orion, P-7, P-8A Poseidon, C-130 Hercules, C-27 Spartan, KC-46 Pegasus, V-22 Osprey, H-53 Stallion and King Stallion, H-46 Sea Knight, AH-1 Cobra, UH-1 Huey, H-60 Blackhawk and Seahawk, and MQ-9 Reaper.
In addition, the kinds of testing performed at WSL include:
- Full-scale operational aircraft/rotorcraft
- Structural response to ballistic impacts (projectile and warhead fragments)
- Hydrodynamic (hydraulic) ram pressure effects
- Aircraft fire-detection and fire extinguishing systems
- Fuel-ingestion investigations of engines under full-up operating conditions
- Warhead detonations/fragments against airframes or running engines
- Thermal and structural tests of advanced composite materials/airframes
- Infrared signature tests (using a 360° rotatable mount)
- Critical systems armor
- Propulsion systems
- Simulated in-flight and carrier-deck pool fires
- Static and simulated in-flight canopy and crew ejections
- Communication link payout studies
- Aerodynamic studies (40–600 knots), including flutter, fuzing, aircraft stores separation, parachute systems.
Likewise, WSL’s efforts have contributed to the development, testing, and implementation of numerous vulnerability reduction technologies onboard U.S. military aircraft, including:
- Fire Suppression Technologies (including active fast-acting extinguishing systems [fixed-wing/rotary-wing] and passive fire suppression systems [rotary-wing])
- Critical systems armor protection (rotary-wing)
- Fuel tank ullage inerting technologies (fixed-wing)
- Flammable fluid leak detection and shut off (fixed-wing)
- Self-sealing and self-healing leak mitigation technologies (rotary-wing).
UNIQUE TESTING EXAMPLES
Over the years, as threats and the enemy’s use of them have evolved, WSL has adapted and expanded its capabilities, approach, and methods. The following are a few examples of particularly unique WSL test and threat capabilities.
Remoted Hover Operation/Dynamic Rotor Blade Targeting
In 1996, engineers developed and demonstrated the capability to fire live munitions at a AH-1 Cobra helicopter’s rotor system while operating in a hover in-ground effect condition (see Figure 7). The effort added the ability to evaluate the helicopter’s component and system responses to a hit while in-flight (hover). This remote control capability allowed the helicopter to be flown in self-powered hover, while steadying its position in space to ensure accurate aiming of the gun system onto rotor component (e.g., blades, pitch links, pitch beam, swashplate).
METS MANPADS Testing
Prior to 2008, live fire testing of aircraft against a man-portable air defense system (MANPADS) threat required setting up a one-time-use test at a remote area of NAWCWD land ranges (see Figure 8). The testing included positioning the aircraft on top of an elevated tower and mounting infrared (IR) heating elements at the desired hit point for acquiring MANPADS missile lock and track. The MANPADS missile was typically launched 1.5 miles away, with the missile then tracking toward the IR signal source (hit point) located down range. Firing a MANPADS missile at a nonmoving target near the ground was risky, challenging, and often resulted in the missile missing its intended target. In addition, the remote setup required relocation of WSL equipment and capabilities, which added complexity and cost to the overall operation, as well as created many test limitations that ultimately resulted in reduced instrumentation, aircraft monitoring, data collection, and choice for the engagement scenario tested. Finally, firing the MANPADS using the standard method for delivery to the target created a fixed condition for velocity (intercept) and was not suitable for replicating other aircraft-to-MANPADS threat engagements.
Accordingly, from 1994 through 2008, in an attempt to address the aforementioned deficiencies, WSL engineers established the capability to fire MANPADS threats at aircraft with pinpoint accuracy, required approach angles, and intercepting speed. WSL first developed a Missile Engagement Threat Simulator (METS) composed of a high-pressure gas gun to propel items such as missiles, liquids, and other objects, including engine fragments (see Figure 9). In addition, a MANPADS firing capability from the METS gun was added, allowing for close proximity firing of the MANPADS threat at an aircraft that is operational, controlled, monitored, fully instrumented, and under HIVAS airflow.
Until recently, the LFT&E of an RPG required moving the aircraft in closer, which created issues in replicating some threat-encounter conditions, as well as possible effects on aircraft vulnerability results. To address this limitation, WSL engineers in 2016 developed the capability to deliver an RPG (with a live warhead) on target with pinpoint accuracy and up to its maximum fly-out speed within 10 m of launch (see Figure 10). The new RPG launcher provides live fire testers with the capability to replicate all threat encounter and engagement conditions needed to support the DoD and the survivability community.
Since its establishment a half century ago, WSL has experienced ongoing and significant change and expansion. As new threats and needs have continued to emerge and develop, the laboratory has likewise continued to adapt and innovate to provide the DoD with the most modern and capable LFT&E facilities. And WSL leaders are committed to building on this 50-year legacy to help ensure the survivability and effectiveness of U.S. air and weapons systems for many more years to come.
ABOUT THE AUTHOR
Mr. Marty Krammer is an aircraft vulnerability engineer at the Naval Air Warfare Center Weapons Division in China Lake, where he currently leads LFT&E activities for multiple Navy aircraft programs. With more than 29 years of experience, he has supported numerous aircraft vulnerability reduction and testing programs, including AV-8B, F-15, F-14, F/A-18, JSF, AH-1, UH-1, H-60, V-22, and CH-53; and he has provided many recommendations to reduce the vulnerability of these aircraft. In particular, Mr. Krammer specializes in aircraft fire, fuel tank self-sealing, and explosion protection. He also serves as the Navy co-chairman of the Joint Aircraft Survivability Program Office’s Vulnerability Reduction and Analysis Subgroup, as well as the Navy Deputy Test Director for the Joint Live Fire Aircraft program, investigating vulnerability issues associated with fielded Navy aircraft.