The 2006 retirement of the last F-14D Tomcat knocked Northrop Grumman out of the ranks of prime contractors of U.S. fighters for the last 15 years, but perhaps not forever.

An ever-expanding shopping list of new air dominance capabilities desired by U.S. and allied air forces has prompted a spurt of product development in the U.S. tactical aircraft market from the maker of the flying wing B-2 and B-21 strategic bombers.

• Model 437, unmanned Model 401 concepts revealed
• Family of systems approach for next-generation air dominance

The unveiling on Sept. 8 of the Scaled Composites Model 437—an attritable-class unmanned aircraft system (UAS) concept design—and a proposed new unmanned conversion of the 4-year-old, manned Model 401 demonstrator offer new hints of the company’s wider plans for the next generation of air dominance platforms.

Combined with the SG-1, a flying-wing UAS concept revealed last year, Northrop appears set to make a new run at the U.S. tactical aviation market now split exclusively between Boeing and Lockheed Martin.

Sporting a new family of concepts with the SG-1, Model 401 and Model 437, Northrop has developed a portfolio of options at a key moment. The U.S. Air Force is sorting through a long list of overlapping requirements for a Next-Generation Aerial Target, a new class of swarming, attritable aircraft, and a Next-Generation Muti-Role UAS, with advanced networking and autonomous capabilities added to such familiar design drivers as signature control, speed, range, ceiling and payload capacity.

All three concepts were highlighted in a dramatic presentation of the company’s air dominance portfolio on Sept. 8. On an isolated corner of the U.S. Air Force’s Plant 42 in Palmdale, California, Northrop executives offered a group of journalists a rare peek inside their plans for the future of tactical aviation. Inside a hangar on Site 7, the former home of F-5 production, Northrop assembled the carrier-based X-47B demonstrator, which is now described as an ancestor of: the SG-1 concept; the optionally piloted Scaled Composites Firebird; a manned Model 401 with a radome over the canopy to represent the UAS version; a scaled-model of the Model 437 concept; and an MQ-4C Triton.

“We’ve got some finished products in the hangar here,” says Jane Bishop, Northrop’s vice president and general manager for autonomous systems.

The presentation of this investment that spans two decades points to Northrop’s interest in capturing the ultimate prize: a prime contractor role to develop and build the replacements for the Lockheed Martin F-22 and the Boeing F/A-18E/F under the Next-Generation Air Dominance (NGAD) programs.

Air Force officials consistently describe the classified NGAD capability as a family of systems based around five new technologies. The only acknowledged technology in development for the NGAD portfolio is the Next-Generation Adaptive Propulsion (NGAP) program, a fighter engine with a new, three-stream core.

The NGAP is not to be confused with the related Adaptive Engine Transition Program (AETP), which seeks to develop a three-stream engine with a 45,000-lb.-thrust rating. The AETP is a candidate to replace the Lockheed F-35 engine, and, according to Pratt & Whitney, the NGAP represents a smaller engine to power a likely twin-engine, next-generation fighter. Pratt and GE Aviation are competing over the next four years to win a potential NGAP production contract.

A future NGAD airframe powered by the NGAP is the focus of a brewing competition among Boeing, Lockheed and Northrop. Although Boeing continues to build F/A-18E/Fs and F-15EXs while Lockheed keeps delivering F-35s and F-16s, Northrop is not starting from scratch in the fighter market.

Northrop employees at Site 4 at Plant 42 build the center fuselage of the F-35, including the serpentine ducts that represent one of the most complex structures produced by the global aerospace industry. In El Segundo, California, Northrop builds the center fuselage and vertical tails of the F/A-18E/F. Indeed, the F/A-18 family would be credited as a Northrop design today, but in the mid-1970s the Navy directed the company to transfer the prime contractor role to McDonnell Douglas, which later merged with Boeing.

Although Northrop has not delivered a fighter since the last F-14 in 1991, Northrop’s aircraft design team has been active in the tactical market. When the Air Force Research Laboratory partnered with industry to explore a tail-less supersonic fighter under the Efficient Supersonic Air Vehicle program in 2015, Northrop produced an unclassified design concept. The result—a futuristic fighter design featuring VHF-band stealth—was featured in Northrop’s Super Bowl commercial in 2016.

More activity may be hidden behind proprietary and classified walls, but the first public sign of Northrop’s interest in tactical aircraft came with the Model 401. The oddly shaped aircraft—featuring a sharply anhedral-dihedral lambda wing, a dorsal engine inlet and YF-23-style, V-tailed ruddervators—was named quickly after its first flight in 2017 on social media as the “Son of Ares.” The latter is a reference to an early-1990s Scaled Composites prototype aircraft, which the Air Force briefly considered as a replacement for the Fairchild Republic A-10.

Although serving since 2017 as a flying testbed of a range of mystery payloads, both Model 401s shown in Palmdale, California, are in some ways primitive. A hardy crew of test pilots suffer 3-hr. missions at 25,000 ft., in an unpressurized, unheated cockpit. A 12-volt, bolt-on device designed for motorcycles offers the only heating and cooling in the cockpit. To keep production costs for the self-financed aircraft minimal, the Model 401s lack yaw dampers. A resulting Dutch roll-induced waddle is a persistent nuisance for pilots, but does not affect the data collected by the test payloads, says Brian Maisler, a Model 401 pilot.

In other ways, the aircraft is easy to fly, with lightly balanced, mechanical flight controls, Maisler adds. For a 7,500-lb. aircraft, the Model 401 offers surprising payload capacity and versatility with removable leading edges, a nose radome and a large compartment just behind the cockpit.

The two Model 401 testbed aircraft have an undisclosed customer, but Northrop sees broader potential with a few design tweaks. The used JT15D engines now powering the Model 401 come with a relatively cheap $300,000 price tag, but limit the aircraft’s endurance to about 4 hr. at Mach 0.65 on 2,000 lb. of fuel. By simply switching to the more expensive Williams International FJ44 turbofan, Northrop can nearly double the range of the Model 401. By upgrading the engine and removing the human pilot, the proposed Model 401 UAS could be pitched for the Air Force’s emerging requirements for a low-cost surveillance asset.

The Air Force has outlined a bold vision for the future of air dominance, although some of the key details are being assembled. The Skyborg autonomy system seeks to insert an artificial intelligence “brain” into a future family of UAS. The Low-Cost Attritable Aircraft Platform-Sharing program, which supported the Model 401, aimed to provide an automotive-style, reconfigurable aircraft chassis, which could be integrated with the Skyborg brain.

But the Air Force is still working out other details. In two requests for information released since June 2020, the service has asked for industry input on which missions such aircraft should perform. As those questions are resolved, the Air Force must decide how those tasks should be split between relatively expensive, reusable UAS and lower-cost, attritable aircraft that are cheap enough to lose.

To satisfy the more capable and reusable UAS requirement, Northrop has already shown off the flying-wing SG-1 concept for a stealthy and armed UAS, which would be priced higher than $20 million.

The Model 437 unveiled on Sept. 8 is Northrop’s response for the attritable requirement. Borrowing the lambda planform, dorsal inlet and V-tailed ruddervators of the Model 401, the $5-6 million UAS, including a $2.4 million Williams International turbofan, represents Northrop’s answer to the Kratos XQ-58A Valkyrie and Boeing Airpower Teaming System.

Like those competing aircraft, the Model 437 would offer 3,000-nm range at Mach 0.8, says Scaled Composites President Cory Bird. The runway-based aircraft is designed to carry a payload as large as a side-looking radar or two Raytheon AIM-120 Advanced Medium-Range Air-to-Air Missiles internally.

The Model 437 represents the latest concept design from Northrop-owned Scaled Composites, which has averaged a first flight of a new aircraft annually since it was founded in 1982. As the Air Force continues to work out the details of the NGAD family of systems, Scaled Composites’ philosophy of approaching every new aircraft design differently may prove useful.

“We hope,” says Bird, “to accidentally stumble into something that really works.”