Northrop Grumman is to lead Boeing and Lockheed Martin in studying energy-optimized aircraft with integrated hybrid-electric system architectures under the U.S. Air Force Research Laboratory’s (AFRL) Integrated Vehicle Energy Technology (INVENT) program.

Goals of the five-year INVENT Spiral 1 program include extending range and endurance 10-15 percent, increasing power and thermal capacity by 10-30 percent, overcoming cooling challenges in low-observable platforms, and reducing lifecycle costs. (See charts pp. 6-7.)

Because the stealthy F-22 and F-35 dump their heat into their fuel they are “flying thermos bottles”, says Steven Iden, AFRL’s Invent program manager. And the heat loads in the F-35 are three to five times what they are in the F-16, he says.

This causes cooling challenges on the ground before takeoff, when flying at low altitude, and when landing with limited fuel. INVENT aims to generate less heat and use other heat sinks. This includes finding stealthy ways to use ram-air cooling.

AFRL is awarding Tier 1 and 2 suppliers smaller contracts to study the three main INVENT technologies: hybrid electrical-thermal management systems, robust electrical power systems and high-performance electromechanical actuators.

Under an 18-month, $8 million Phase 1 contract, the airframe team led by Northrop Grumman will study the integration of these technologies into tactical, unmanned and long-range strike platforms, as well as assess their benefits.

This will be followed by a second phase under which AFRL and industry will build an INVENT Systems Integration Facility (ISIF) and conduct an integrated ground demonstration of the consensus architecture for the energy-optimized aircraft.

Iden says the ISIF is planned to be built at Wright-Patterson Air Force Base, Ohio, with Spiral 1 ground demonstrations to begin in 2012. AFRL is planning flight demonstrations in 2015, with two further spirals for future platforms to follow over the next 10-15 years.

Photo: Lockheed Martin