The Weekly Debrief: Can A Blended Wing Body Airlifter Make The Military Cut?

Z-5 in flight

Partnering with Northrop Grumman, JetZero has proposed the Z-5 for the U.S. Air Force’s program to build a large-scale advanced tanker-transport demonstrator.

Credit: JetZero

A decision will be announced by the U.S. Air Force on Aug. 16 that could decide the future shape of the strategic mobility fleet. 

The Air Force will unveil the winner of a Defense Innovation Unit (DIU)-managed competition to build and fly a Boeing 767-sized, blended wing body demonstrator within four years. 

The demonstrator could inform decisions in the late 2020s on the next air refueling aircraft to succeed the KC-46, as well as replacements for the Lockheed Martin C-5M and Boeing C-17 in the decades ahead. 

The terms of the DIU solicitation are clear that the demonstrator will be a blended wing body (BWB), a three-decade-old concept that optimizes what would be the inboard section of a traditional wing to carry a payload and serve as an aerodynamic control surface.

The demonstrator’s scheduled first flight in 2027 will make it a contender to fill the Air Force’s emerging requirements for a Next Generation Air Refueling System (NGAS) and a Next Generation Airlifter (NGAL).

To be sure, the BWB still faces competition. The Air Force Research Laboratory’s (AFRL’s) Rocket Cargo program proposed to transport C-17-sized cargo or personnel anywhere around the world in 1 hr. with a suborbital space vehicle. DARPA’s ongoing LibertyLifter program aims to demonstrate an experimental, C-17-sized seaplane that can haul cargo or personnel across the Pacific mostly in wing-in-ground effect, but with the capability to fly up to 10,000 ft. if necessary. New ideas for standard tube-and-wing aircraft designs, including Boeing’s NASA-funded Transonic Truss-Braced Wing (TTBW) demonstrator, also could be in the mix, as well as incrementally better versions of standard military airlift designs today.

But the BWB program has a few advantages for a new demonstrator program. Since McDonnell Douglas engineers conceived the concept more than 30 years ago, the design has been thoroughly researched, including data from 122 flights of the NASA-funded, subscale Boeing X-48 between 2007 and 2013.

A follow-on plan to test a NASA-funded, full-scale demonstrator led nowhere. Congress cut NASA’s X-plane funding in 2018, forcing the agency to choose only one project to follow the Lockheed X-59 low-boom supersonic demonstrator. In 2020, the agency selected Boeing’s TTBW over the BWB for a demonstrator to prove out technology for the next generation of single-aisle airliners.

Meanwhile, the Air Force favored more ambitious technologies, such as AFRL’s Rocket Cargo program. Starting in 2022, however, support for the BWB emerged from a perhaps unlikely source: the Air Force’s Office of Energy, Installations and Environment. During Aviation Week MRO Conference in April 2022, the office unveiled plans to launch a BWB demonstrator. 

“The BWB is one of the single most impactful technology opportunities for future U.S. Air Force aircraft, both in terms of capability improvement and greenhouse gas emissions reduction,” the Air Force said in a follow-up fact sheet released in June 2022. 

Congress offered full support. The office received a $41.9 million budget in fiscal 2023 to kick off the DIU competition. The Air Force requested another $88.2 million for fiscal 2024. 

The goal is now to verify that the promises of the BWB configuration—including 30% less fuel consumed than a C-17, and 60% more off-load capacity at range compared to a KC-46—are achievable. The demonstrator stops short of a mission-focused prototype aircraft. The selected BWB will not be equipped with a refueling system or a cargo ramp.

The Air Force mobility fleet may need a new aircraft in two or three decades and perhaps a new tanker even sooner. The time has finally come to find out if a BWB aircraft will be competitive.

Steve Trimble

Steve covers military aviation, missiles and space for the Aviation Week Network, based in Washington DC.