YF-23 Designer Offers His Take On Boeing’s F-47 NGAD Configuration

When the U.S. Air Force announced Boeing as the winner of the Next-Generation Air Dominance fighter competition and released heavily doctored artist’s impressions of the F-47, renowned aircraft designer Darold Cummings offered to analyze the design for Aviation Week.

Chief configuration designer for the YF-23, Northrop’s contender for the Air Force’s Advanced Tactical Fighter (ATF) competition won by Lockheed’s F-22, Cummings continues to be active in aircraft design through his consulting company, ForzAero. He helped Aviation Week analyze China’s new J-36 and J-50 fighters (AW&ST Jan. 13-26).

Cummings had little to go on beyond his more than 50 years of experience designing aircraft, ranging from trainers and spaceplanes to long-range strike platforms and stealthy transports for Northrop, Rockwell and Boeing. Only two F-47 images were released by the Air Force, with key details obscured.

Rather than try to deduce the F-47’s design directly from heavily redacted images, Cummings chose to develop his own configuration—dubbed the Black Sabre as a nod to Boeing’s fighter heritage—that was shaped by design considerations consistent with the F-47’s intended mission.

The images appear to show a tailless aircraft with a canard configuration. At first, Cummings was skeptical of a canard on a stealthy fighter. But through its purchase of Rockwell in 1996 and McDonnell Douglas in 1997, Boeing has a history of canard designs stretching back to Rockwell’s Advanced Fighter Technology Integration concept, developed by Cummings in 1973, which led to the uncrewed HiMAT testbed.

Both McDonnell Douglas and Rockwell proposed canard designs for the ATF in 1982, and the Rockwell-MBB X-31 was designed in 1995 to be a tailless demonstrator controlled by a canard and thrust vectoring. Flown in 1997, McDonnell Douglas’ X-36 was a subscale model of a stealthy tailless fighter with a canard, split ailerons and thrust vectoring for directional control.

For the F-47, a canard could allow Boeing to dispense with thrust vectoring, a feature of the F-22, Cummings contends. “The canard, along with spliterons for yaw control and flaperons for pitch control, should provide all the control authority necessary for combat operation,” he says.

The YF-23 did not have thrust vectoring, engines exhausting into upper-fuselage channels. “I believe the aft exhaust deck will be fixed, with an actively cooled upper surface for infrared [IR] suppression,” Cummings adds. “This, combined with the deletion of thrust vectoring, should greatly reduce the IR signature.”

The released F-47 images give no hint of the wing planform, but Cummings is extremely skeptical of the apparent wing dihedral. “This is totally inappropriate for a fighter,” he notes. “High wings are naturally stable—in fact, too stable for good maneuverability.”

Instead, modern high-wing fighters incorporate anhedral to make the aircraft less stable and more maneuverable. Boeing’s Bird of Prey tailless stealth demonstrator had dihedral inboard but downturned outer wing sections, and there is no evidence of balancing outboard anhedral on the F-47.

As for the planform, with the canard layout, this could either be a clipped trapezoid—as on the F-22 and Chinese J-20—or a lambda wing, Cummings says. Through McDonnell Douglas, Boeing also has a long history with the lambda planform, including the X-36 and its contender for the Joint Strike Fighter.

But Cummings sees a problem. “This type of planform would produce a high cross-sectional area at the aft of the aircraft, which results in a poor Sears-Haack area distribution,” he says. “This would make supersonic cruise in dry thrust difficult.” As a result, his design has a clipped-trapezoid wing.

The F-47 images give no hint of the inlet locations or weapon bays. Drawing on his aircraft design experience, Cummings chose F-22-style side inlets as well as main and side bays for the Black Sabre. “This allows for the best integration with the least impact to the maximum fuselage cross section,” he says. “This improves overall fineness ratio, which decreases air vehicle drag.”

A final area of debate involved the F-47’s apparently broad nose. While indicative of a lifting forward fuselage, the nose appears to be too wide for pilot visibility to comply with military standards. By shortening the nose, Cummings found an acceptable compromise.

His final Black Sabre concept is not the F-47, but it is a design that illustrates how a canard-equipped sixth-generation fighter could look. It also helps shed light on the challenges Boeing faced in producing a configuration that balances stealth, range and agility.