The Pentagon has tapped aviation startup JetZero to develop a large, full-scale demonstrator aircraft to test a revolutionary Blended Wing Body configuration. It could potentially lead to the development of stealth aerial refueling tankers and transport planes with much greater fuel efficiency.
Air Force Secretary Frank Kendall told an audience at the Air and Space Forces association on August 16 that the Pentagon would allocate $235 million through 2027 to enable the California-based JetZero to complete a to-scale XBW-1 demonstrator that should fly by first quarter 2027. The Air Force and NASA would also contribute to realizing the test aircraft, as would JetZero partner Scaled Composites, owned by Northrop-Grumman.
Artwork earlier released by JetZero for its Z-5 concept aircraft shows a futuristic design, combining a tailless fly-wing airframe with folded wingtips that blends into a triangular fuselage. An airliner-style nose/cockpit protrudes from the front while two turbofan engine pods are slung atop the rear fuselage, resulting in a look reminiscent of the Quinn jet from the Avengers movies.
JetZero claims that the Z-5s are built with light composite-material skin and relatively light weight LEAP or GTF turbofans could serve as a midmarket airliners seating 230-250 passengers for flight out to 5,750 miles.
The Blended Wing Body (BWB) design concept seeks to meld the low radar cross section and drag-reducing efficiencies of a flying wing-shape aircraft (like the Air Force’s manta-shaped B-2 bombers) with the hauling capacity of a traditional cargo plane or airliner.
The anticipated benefits should interest both civilian and military aircraft operators, as BWB aircraft should produce much less noise and drag. The minimized drag results in increased range, lower overall fuel consumption, greater potential mission payloads (in terms of stored fuel or cargo), and reductions to carbon emissions potentially as high as 80% (if combined with sustainable aviation fuel).
Earlier Air Force documents indicate that the service is seeking a BWB aircraft with high-efficiency engines that’s at least 30% more aerodynamically efficient than a Boeing 767 or A330 airliner.
A Northrop-Grumman official, meanwhile, claims that JetZero’s aircraft could achieve a “roughly 50%” increase in efficiency, leading to doubled range or payload. They also claim that the craft could boast some short takeoff and landing (STOL) capability and reduce physical footprint, easing operations from sparse airbases. That could fit in neatly with the ‘Agile Combat Employment’ strategy now promoted by the Pentagon to disperse aviation assets to secondary bases—or even highways—in wartime to limit vulnerability to enemy precision strikes.
Given the huge number of flying hours that airliners and refueling tankers accumulate yearly, such improvement would translate to billions of dollars saved annually in operating costs and big reductions to carbon footprint. The Air Force notes that large transports account for 60% of the service’s annual jet fuel use.
The Drive observes that the concept’s top-mounted engines are effectively shielded from detection by radar and infrared sensors scanning from below, and would also produce less noise (JetZero claims that the noise would be on order of 15 decibels lower—31 times less—than other designs), as sound waves would primarily reflect upwards off of the aircraft’s upper surfaces.
Thus, if JetZero’s demonstrator is successful, it could pave the way for a new generation of large-haul aircraft with greater discretion and lower fuel consumption. It could also be the first step towards large military aircraft being able to fly closer to hostile airspace at more acceptable levels of risk.
What exactly is a Blended-Wing Body aircraft?
The Blended Wing-Body concept—also known as hybrid-wing body (HWB)—involves transforming a traditional airplane’s tube-and-wing configuration by “stretching” the fuselage sides into the forward edges of the wing to form a partial flying-wing that still retains a capacious central fuselages. Ideally, this results in an aircraft that’s fairly stealthy and optimized for minimal drag, yet that can still carry large payloads. And it actually flies.
Downsides of BWB design include increased airframe complexity, challenges devising flight control systems for a tailless aircraft without horizontal and vertical stabilizers, and reduced window seating for passenger planes.
Prototype BWB aircraft dating back to World War II include the U.S.’s bizarre-looking XP-67 fighter and the British Miles M30 demonstrator. Later, better-known designs with partial blended-wing characteristics include the SR-71/A-12 spy planes and the B-1 Lancer and Tu-160 Blackjack strategic bombers.
Since the 1980s, aircraft giant McDonnell Douglas and its purchaser, Boeing, are credited with advancing modern BWB research, particularly through the BW-17, X-45B, and X-48 demonstrators and prototypes.
BWB concept aircraft currently being proposed include Bombardier’s EcoJet (aiming at a 50% emission reduction), and Airbus’s Zero-Emissions concept airliner (with 200 seats and hydrogenn hybrid turbofan engines). Airbus test-flew a miniaturized airliner demonstrator in 2019.
On the military side, in January of 2023, Boeing unveiled its own concept art for a BWB stealth tactical cargo plane.
Why the Pentagon wants stealth tankers and transports
While the Pentagon claims that drag reduction and its resulting fuel efficiency are the primary motivators of interest in BWB aircraft, there is no avoiding the fact that they’re also seen as a possible low-cost gateway to fielding much stealthier tanker and transport planes.
Such large, subsonic aircraft types aren’t ordinarily intended to fly anywhere close to enemy firepower. But various factors make that hard to ensure in the 21stcentury.
First of all, the latest long-range anti-air missiles can now traverse much greater distances into what formerly was considered a relatively safer ‘backfield’ behind the frontline. For example, Russia’s S-400 surface-to-air missiles (SAM) system, or R-37M missiles air-launched by fighters, can theoretically target aircraft up to 250 miles away.
While odds are poor of hitting at maximal range, larger and slower aircraft are exactly the kind that will struggle most to evade. Picket lines of warships armed with long-range SAMs could also project bubbles of interdicted airspace at inconvenient areas.
Worse, stealth fighters like China’s J-20 are likely to be assigned to stalk valuable support planes, and can creep closer—and from unexpected angles—before releasing missiles. This allows them to pose a serious, dynamic threat to tanker aircraft in the event of a major conflict. Reducing a tanker’s radar cross-section, therefore, could considerably mitigate the risks of being detected and targeted by long-range radars and missiles.
Higher-end stealth tanking could also be transformative offensively. The Pentagon’s F-35 and F-22 stealth fighters are relatively short-ranged, which limits how deep they can penetrate or patrol contested airspace. A stealth tanker that could accompany them close to—or even inside—the enemy air defense zone could multiply effective combat range in sensitive areas, curbing one of the major shortcomings of U.S. stealth airpower.
Stealthier transports are also compelling, as long-range anti-aircraft missiles could imperil cargo deliveries to friendly airbases. For example, a series of simulations run in 2021 found that attempts by the U.S. to air transport ground reinforcements to Taiwan ended with all the transport planes being shot down by Chinese picket ships and fighters forming a blockade.
More ambitiously, a stealth transport would be useful for inserting airborne and special operations forces behind enemy lines.
While the U.S. does operate MC-130 special ops transports optimized for some penetration capability (alongside stealth-optimized helicopters and Osprey tilt-rotors), the proliferation in the 21st century of more lethal air defenses and capable sensors would sharply limit their useability against a capable adversary. Already, in Russia’s war in Ukraine, both sides have been compelled to forsake airborne/air assault operations and deep insertions due to the density of air defenses and radar coverage.
A stealth-optimized BWB plane might be able to slip through weak spots in that radar-coverage. Its reduced-noise engines could also prove highly advantageous, though additional infrared-red signature reduction measures and active protection systems might be required as well.
An Air Force general claims the service’s Next Generation Airlift System(NGALS) will incorporate technology from its B-21 stealth bomber project, suggesting that radar cross-section optimization is likely being look at for future state-of-the-art transport planes.
Other large, vulnerable aircraft types that might be candidates for BWB-based configurations include maritime patrol aircraft and long-distance surveillance/reconnaissance planes.
It’s important to note here, however, that BWB designs are unlikely to be as discrete as current stealth combat aircraft like F-35s. They may instead be just stealthy enough to mitigate long-distance threats.
The potential advantages of BWB aircraft for long-distance operations, and as support for landing and takeoff from remote bases, fits in with the strategic realities of the Pacific. There, transoceanic distances, tiny Pacific islands and dense Chinese anti-aircraft and land-attack missiles sharply constrain how and where the U.S. can exert military power.
The blended wing-body future?
The path to a conceptual KC-Z stealth tanker recently became more direct when, in March of 2023, the Air Force canceled plans to procure 75 new KC-Y series tankers that were intended to bridge the gap between the futuristic KC-Z and the currently-in-production Boeing KC-46A Pegasus tankers. The new plan is for a second order of improved KC-46s to fill the gap—an approach likely requiring less time and money.
However, the Pentagon isn’t strictly committed to a BWB design solution. JetZero's demonstrator is more of a venture-capitalist style bet on advancing a highly promising technology.
In fact, in the service’s next-generation tanker program, a BWB design will reportedly be pitted against a traditional airliner-based tanker and a fully stealth-optimized tanker. That latter would presumably be a ‘true’ flying wing design that could be based on the forthcoming B-21 stealth bomber. Thus, BWB aircraft seem to be a ‘medium’ solution between these two survivability extremes.
A rival concept (or potential complement) to large BWB aircraft could involve focusing on smaller, uncrewed transports and refueling tankers, like China’s Scorpion-D transport drone and the Navy’s new MQ-25 Stingray refueling drones. That concept accepts some loss in maximum payload and survivability (ie. fewer expensive defensive countermeasures and stealth optimizations) in exchange for much lower costs and greater fuel efficiency and expendability.
Until new planes are ready, the Air Force will seek to improve its existing tankers (and perhaps some transports) by integrating additional self-defense countermeasures—possibly even including laser-based active protection systems that blind or outright destroy incoming missiles.
On the flipside, successful maturation of BWB designs has the potential to transform civilian aviation by ushering in a more fuel-efficient and less pollution-heavy design paradigm for future airliners.
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