The advances of Aurora’s demonstrator ensure that the company’s fan-in-wing VTOL experiments will extend well beyond DARPA’s SPRINT.
Aurora Flight Sciences, a Boeing subsidiary, is poised to redefine the way the Pentagon views vertical takeoff and landing (VTOL) technology. Recently, the company unveiled a revised fan-in-wing VTOL aircraft design under the imprimatur of the Defense Advanced Research Projects Agency (DARPA) Speed and Runway Independent Technologies (SPRINT) program. This cutting-edge concept promises to revolutionize military air mobility by combining high-speed performance with runway-independent operations, ideal for contested environments where traditional airstrips are unavailable or vulnerable.
As global defense needs shift toward agile, stealthy transport solutions, Aurora’s fan-in-wing technology stands out for its possible uses in special operations, logistics, and personnel recovery missions.
Despite the Aurora’s real advantages, though, DARPA passed on it—instead choosing the Aurora’s competitors at Bell to move forward in the SPRINT program. Still, Aurora’s demonstrator shows great promise that will not be forgotten when the SPRINT program ends.
DARPA’s SPRINT Program Wants to Reinvent VTOL Aircraft
DARPA’s SPRINT program, created to address the limitations of current rotorcraft and fixed-wing aircraft, seeks to demonstrate an X-plane that achieves cruise speeds of 400-450 knots while enabling VTOL capabilities on unprepared surfaces.
This initiative aligns with US Special Operations Command (SOCOM) interests in high-speed VTOL (HSVTOL) platforms, particularly for operations in high-threat areas, such as the Indo-Pacific. Aurora was one of four competitors selected for Phase 1A of SPRINT, advancing to Phase 1B after a conceptual design review, where it refined its proposal to meet DARPA’s ambitious goals.
The core of Aurora’s design is the fan-in-wing (FIW) technology, which embeds lift fans within a blended wing body (BWD) platform. This integration allows for seamless transitions between vertical and horizontal flight, minimizing drag and enhancing efficiency.
The revised concept, unveiled in May 2024, features significant updates from the initial four-fan, crewed configuration. Now uncrewed for risk reduction during testing, it incorporates three lift fans in a triangular arrangement—one in the nose and two in the wings—along with refined composite exterior and angular air intakes positioned under the nose for improved aerodynamics.
These changes simplify the demonstrator, accelerating the path to flight testing while maintaining scalability. For instance, the FIW system can expand to four or more fans for larger variants, making it adaptable for crewed missions in the future.
What to Know About Aurora’s SPRINT X-Plane
Because the aircraft has yet to be built, many of its specifications are unknown and could change amid further testing. Yet from what has been released to the public, the X-plane’s initial design is promising:
- Length: Unknown
- Wingspan: 45 ft
- Weight: Unknown
- Engines: Off-the-shelf turbofan/turboshaft engines
- Top Speed: 450 knots (518 mph, 833 km/h)
- Range: Unknown
- Service Ceiling: Unknown
- Loadout: 1,000 lb payload
- Aircrew: Unknown
Technically, the aircraft boasts impressive specs tailored for military demands. Its high speed far surpasses traditional helicopters while enabling VTOL, short takeoff and vertical landing (STOVL), super short takeoff and landing (SSTOL), and conventional operations. During VTOL modes, flat panels and split circular covers seal the fans for low-drag forward flight, with auxiliary doors potentially diverting air to enhance stability.
In the future, Aurora envisions scaling the X-plane to a 130-foot wingspan model with a 40-foot payload bay, matching or exceeding the range and capacity of existing fixed-wing transports, such as the ubiquitous C-130. While that might sound far-fetched, the fact remains that Aurora has demonstrated with their fan-in-wing VTOL system that they can achieve such lofty aims.
Development milestones underscore the design’s progress. In 2024, Aurora completed ground effect testing on a 4.6-foot wingspan model, confirming negligible “suck down” effects in hover and optimal landing gear height to avoid pitching issues. By March of this year, stability and control wind tunnel tests at Boeing’s V/STOL facility near Philadelphia validated low-speed handling and transition dynamics using a 20 percent scale model.
Why Did DARPA Choose Bell Textron’s Project Instead?
In short, Aurora has conceptualized a truly revolutionary aircraft, and tests have borne out its most impressive features. Yet DARPA selected Bell Textron for the next phase which occurred in July over Aurora’s product—highlighting the competitive nature of this particular program.
Bell’s product is also impressive—a sleek aircraft with folding rotors on either side of a central cockpit—but its design is far more conventional, and far less groundbreaking, than Aurora’s.
Still, the advances of Aurora’s demonstrator ensure that the company’s fan-in-wing VTOL experiments will extend well beyond DARPA’s SPRINT. In contested airspaces, where anti-access/area-denial (A2/AD) threats loom, this technology could enable rapid insertion of troops and supplies without relying upon vulnerable runways.
Indeed, this system drew from historical concepts, such as the 1960s Ryan Vertifan, but leverages modern composites and autonomy for superior performance. Looking ahead, while Bell advances in SPRINT, Aurora’s FIW breakthroughs could influence broader applications, from urban air mobility to commercial logistics. The sky is truly the limit with Aurora’s demonstrator.
No one at Aurora Flight Sciences appears too worried about having lost out to Bell—if only because they understand that the demand for their capabilities will be great in the coming years. Indeed, the company has plenty of work ahead; it will be able to apply the hard lessons learned during the SPRINT experiments to more lucrative products.
About the Author: Brandon J. Weichert
Brandon J. Weichert is a senior national security editor at The National Interest. Recently, Weichert became the host of The National Security Hour on America Outloud News and iHeartRadio, where he discusses national security policy every Wednesday at 8pm Eastern. He is also a contributor at Popular Mechanics and has consulted regularly with various government institutions and private organizations on geopolitical issues. Weichert’s writings have appeared in multiple publications, including The Washington Times, National Review, The American Spectator, MSN, The Asia Times, and others. His books include Winning Space: How America Remains a Superpower, Biohacked: China’s Race to Control Life, and The Shadow War: Iran’s Quest for Supremacy. His newest book, A Disaster of Our Own Making: How the West Lost Ukraine is available for purchase wherever books are sold. He can be followed via Twitter @WeTheBrandon.
Image courtesy of Aurora Flight Sciences.
