Thermal management will be a critical factor in a brewing competition to replace hundreds of Lockheed Martin F-22s and Boeing F/A-18E/F Super Hornets, says a top Northrop Grumman executive.
Releasing a new artistic concept of a so-called sixth-generation fighter on 11 December, Northrop Aerospace Systems president Tom Vice singled-out the critical but often overlooked quality of managing all the heat generated by ever-more powerful weapons and sensors anticipated on future combat aircraft.
Northrop’s sixth-generation fighter concept shows the stealthy, swept-wing fighter using a powerful laser weapon to engage multiple targets. Even the best high-power lasers are only 32-33% efficient, meaning 2MW of heat is generated for every 1MW of energy that can be formed into a laser beam, Vice says.
That creates a difficult problem for a stealthy combat aircraft. Venting the heat offboard only raises the aircraft’s visibility to heat-sealing sensors. Another option is to develop a thermal accumulator, which is a path the Air Force Research Laboratory is pursuing under the INVENT programme. An electrical accumulator stores the energy onboard in the same way as a hydraulic accumulator, releasing the latent energy as necessary to generate a surge of power.
But Northrop’s sixth-generation fighter concept eschews the accumulator concept for thermal management. According to Vice, such a system imposes a limitation on the laser weapon’s magazine size or firing rate, forcing the pilot to exit combat until the accumulator is refilled with energy. Northrop is pursuing a concept instead that does not rely on accumulators or offboard venting to manage the heat, but Vice declines to elaborate on the company’s specific approach to solving the thermal management problem.
Northrop’s concept shows a tailless, possibly supersonic vehicle, promising a new breakthrough in manoeuvrability, speed and stealth for a combat aircraft. It also departs from previous sixth-generation fighter concepts released by Northrop by featuring a swept wing, replacing an aft-mounted straight or slightly forward swept wing on previous designs.
The Lockheed Martin F-22 was the first aircraft to blend supersonic cruising speed, advanced stealth and extreme agility in the same package, building on the Northrop’s B-2’s breakthrough combination of stealth and size.
Putting all of those qualities in a package with a new revolution in thermal management technology is the goal for winning the US Air Force’s F-X programme and the US Navy’s FA-XX programme, Vice says.
“The B-2 brought a lot of technology together in a very unique package,” he says. “This airplane will now combine a lot of that, and thermodynamics will be a key discriminator in who wins.”