Simulation Plays Vital Role in Building F-35 Tactics and Aircraft Development

The Lockheed Martin F-35 Joint Strike Fighter (JSF) will not be operational for years to come, but the three US services that will fly the stealthy single-engined fighter have already started to develop tactics for the fifth-generation machine.

"That's already been done with a tri-service approach between the air force, the navy and the Marine Corps," says Col Kevin Killea, the US Marine Corps' (USMC) aviation requirements officer. "The simulation for this aircraft is quite advanced, so even in the early LRIP [Low Rate Initial Production] aircraft that are limited by envelope, we're able to use simulation to help us develop the concept of operations and employment."

The tactics and procedures that are developed in the simulator will form a baseline for the F-35 community until aircrews can fly with an operationally capable aircraft configuration, Killea says. "As we get the envelope to execute it real time in the airplane, we'll refine those techniques and procedures."

The USMC's VMFA-121, which is the service's first operational F-35 squadron, is a long way from being able to "validate" any sort of concept of operations, Killea says. The flight envelope and mission systems software available to the squadron simply do not allow for it.

Simulation also played an vital role in the initial development of the F-35, says USMC Col Arthur Tomassetti, vice commander of the US Air Force's 33rd Fighter Wing and test pilot for both the F-35 and X-35 concept demonstrator.

"We got to use some basic simulators in the labs in Fort Worth [Texas] and some very amazing simulators like the vertical motion simulator (VMS) at NASA Ames," Tomassetti says. "At the VMS, much of how the aircraft flies during slow speed approach and in STOVL [short take-off vertical landing] mode were developed."

Additionally, various malfunctions in different modes of flight would be recreated in the simulator environment to refine the F-35's final design. "I cannot tell you how many hundreds of hours I spent in the sims at Fort Worth and Palmdale [California] going through things-what they call failure modes testing," Tomassetti says.

But for many tests there were no pilots involved. Computers would fly the simulators in order to help discover problems and refine the aircraft's design, Tomassetti says. For example, computers would perform hundreds of take-offs in the F-35 simulator while incrementally adjusting the crosswind by half of a degree every time to gauge the effectiveness of the jet's flight control laws. "If we weren't flying the sim, the computer was flying the sim," Tomassetti says.

There was also some simulation work performed in the air.

"Some 'in flight' simulations were done with aircraft like the [Qinetiq] VAAC [Vectored-thrust Aircraft Advanced Control] Harrier and the [Lockheed] VISTA [Variable stability In-flight Simulator Test Aircraft] F-16 that were modified to fly like the JSF," Tomassetti says.

There were a multitude of simulator types for multiple different roles during the initial development of the jet, Tomassetti says. Some were designed to test flight control laws while others focused on mission systems. Still others were designed to test the cockpit ergonomics of the aircraft and other functions.

"That's a lot of the behind the scenes work that most people take for granted," Tomassetti says.