Aurora Flight Sciences has released new renderings of an uncrewed fan-in-wing vertical take-off-and-landing capable demonstrator aircraft it is currently working on, as well as of a revised vision for a scaled-up cargo aircraft based on the same technology. The demonstrator is being developed under a U.S. Defense Advanced Research Projects Agency (DARPA) program centered on interest in a new high-speed, runway-independent special operations transport plane. Aurora’s unveiling of the new renders also comes amid growing interest from the U.S. Air Force in similar capabilities to support more general distributed logistics missions, especially in contested environments during future high-end conflicts.
Aurora, a subsidiary of Boeing, shared the new renders and provided more information about the work it is doing as part of DARPA’s Speed and Runway Independent Technologies (SPRINT) program earlier today. DARPA awarded new SPRINT contracts to Aurora, as well as Bell, earlier this year. SPRINT, which kicked off last year, is directly tied U.S. Special Operations Command’s (SOCOM) High-Speed Vertical Takeoff and Landing (HSVTOL) project.
“Aurora and Boeing are collaborating on the development of key technologies that combine to deliver a revolutionary solution to mobility challenges in contested environments and across distributed military bases,” according to a press release from Aurora. “Fan-in-wing (FIW) technology combines an embedded lift fan with a blended wing body design to enable vertical lift agility without sacrificing the payload capacity and aerodynamic efficiency associated with today’s fixed wing aircraft.”
“The team is currently designing an uncrewed demonstrator with a 45-ft wingspan and 1,000-pound payload capacity for the SPRINT program,” the release adds. “The propulsion system includes off-the-shelf turbofan and turboshaft engines that would power the vehicle to a maximum of 450 knots true airspeed (KTAS).”
The new rendering of the SPRINT demonstrator is broadly in line with one that Aurora put out in May. It has a blended-wing platform with a v-tail along with three lift fans in a triangular arrangement – one to either side of the central fuselage section and another in the nose end. The revised render shows more streamlined intakes for the main engines underneath the body.
“Earlier this year, the team completed the first of three major test events scheduled for the current phase of the SPRINT program to prove out the feasibility of the FIW technology,” according to Aurora. “The ground effect test, conducted using a 4.6-ft wingspan model with three lift fans, showed that suck down effects created by the lift fans in hover were negligible and that the landing gear is set to the appropriate height to minimize adverse pitching moments from forming during ground operations. Wind tunnel tests planned for late 2024 and early 2025 include a stability and control test using a 9-ft full wingspan aircraft model and a 5¼-ft semi-span embedded lift fan test to model aerodynamic effects.”
“Aurora’s concept is designed to meet or exceed the challenging program objectives that DARPA set for the program. For example, the blended wing body platform is capable of 450 knot cruise speed, and the embedded lift fans with integrated covers allow a smooth transition from vertical to horizontal flight,” the company has also said in the past. “The design also leverages existing engine solutions, shortening development risk and timelines. In addition to VTOL, the aircraft is capable of short take-off and vertical landing (STOVL), super short take-off and landing (SSTOL), and conventional take-off and landing.”
Aurora is currently aiming to reach first flight with the SPRINT demonstrator in 2027. However, the company is already looking to the future.
“The technology demonstrated in the SPRINT X-plane could be scaled to medium and heavy lift aircraft, creating a future family of systems. For example, Aurora envisions a manned, 130-ft wingspan aircraft with four lift fans and 40-ft payload bay,” today’s press release explains. “The FIW aircraft could meet or exceed the payloads, ranges, and speeds typical of fixed wing military transport aircraft while delivering the tactical advantage of true vertical takeoff and landing.”
The rendering Aurora has now released of this larger fan-in-wing design concept shows significant changes from the one it put out back in 2023. The new design has a tailless modified cranked kite planform with lower profile air intakes on top of the rear end of the central body. Like the 2023 render, Aurora’s revised vision for a larger crewed fin-in-wing aircraft still features four lift fans two on either side of the central body.
The design seen in the new rendering appears to reduce some stealthy features and magnify others, notably with the elimination with the vertical tails. What Aurora showed in 2023 did have sharper and narrower wing sections, as well as a more pronounced beak-like nose and chine line along the forward edge of the central body.
The new Aurora rendering also notably shows changes to the design of the lift fan covers. The design the company presented last year had split covers – different versions of the original concept showed circular and hexagonal cover shapes – while the new one has multi-sectioned covers. This is very reminiscent of how the lift fan in the nose of the 1960s-era Ryan Vertifan was covered. The Vertifan had a three-fan configuration that is otherwise similar in some very broad respects to Aurora’s SPRINT demonstrator design. An artist’s conception of a fan-in-wing Special Operations Forces Transport Aircraft (SOFA) concept from Lockheed in the 1980s also shows similar sectional fan coverings.
It is worth noting here that 40 feet is also how long the payload bay is on standard-length variants of the venerable C-130 family, which has long been used as a baseline for mid-tier military airlifter development. Boeing used this same dimensional rubric when crafting a concept that it unveiled last year for a new stealthy aircraft that could be configured as a transport or an aerial refueling tanker. That design, which is intended to take off and land from traditional runways, also has a blended wing body planform that is similar in some broad strokes to Aurora’s proposed SPRINT-derived cargo plane.
The War Zone has also previously pointed out on multiple occasions how Aurora’s work under SPRINT is broadly evocative of a host of vertical and short takeoff and landing-capable designs the U.S. military has at least explored since the 1980s. Supporting special operations missions was a central theme in many of those past development efforts, as you can read about more in this exhaustive two-part feature.
SPRINT together with HSVTOL underscores significant continued interest, especially within the Air Force special operations community, in new, more capable and survivable runway-independent platforms, especially to help get personnel in and out of denied or otherwise sensitive locales. The significant speed and range capabilities that both of those efforts are targeting could be particularly attractive for future operations across the broad expanses of the Pacific region.
“I think the high speed/range, high-speed kind of lower profile ability to get in and out of places that don’t require long runways, I think that would be attractive to any combatant commander,” Air Force Lt. Gen. Michael Conley, head of Air Force Special Operations Command (AFSOC), said in regards to SPRINT and HSVTOL at a media roundtable on the sidelines of the Air & Space Forces Association’s (AFA) main annual conference last month. “It’s certainly a capability we need in the Indo-Pacific, just because of the geography, regardless of an [specific] adversary.”
At the same time, it is not hard to see how the Air Force more broadly, as well as other branches of the U.S. military, might be interested in the kinds of capabilities that designs being developed under SPRINT and HSVTOL, or variants or derivatives thereof, might offer. The U.S. Marine Corps and the Air Force, especially, increasingly envision future operations, especially in the context of a high-end fight against a potential adversary like China, as dispersed affairs. Distributing forces across a large number of operating locations, including far-flung forward sites with limited infrastructure, is seen more and more as not only advantageous, but critical for reducing vulnerability. Large established bases will be prime targets in any future large-scale conflict.
In line with this, diverse and distributed logistics chains are also increasingly seen as essential for supporting these operations, especially in contested environments. A high-speed, long-range, runway-independent, and highly survivable cargo aircraft, crewed or uncrewed, could easily be a part of that future ecosystem.
In fact, the Air Force Research Laboratory just put out a request for information (RFI) about potential Runway Independent Mobility / Next Generation Intra-theater Airlift (NGIA) aircraft last month. NGIA builds on an earlier concept dubbed Last Tactical Leg, according to Aviation Week, which was first to report on this development.
“The Last Tactical Leg proposal envisions an autonomous, hybrid-electric short- or vertical-takeoff-and-landing aircraft,” Aviation Week’s story explains. “This proposed airlifter would deliver small, urgently needed supplies from logistics hubs to forward bases, even with battle-damaged runways on both ends.”
“The Department of the Air Force’s (DAF’s) goal [with NGIA] is to enhance existing airlift capability and capacity with an intra-theater platform that can fight through damaged infrastructure on responsive timelines,” according to the RFI for that effort. AFRL is now “seeking information on advanced configurations, propulsion and power generation/regulation concepts and technologies for a contested logistics aircraft with attributes for agility in the objective area, airlift capacity, speed, range and survivability to sustain joint force operations within the contested environment.”
All of this sounds very much in line with Aurora’s vision for scaled-up designs based on the SPRINT demonstrator. Bell has also previously laid out a concept for a scalable family of advanced tilt-rotor aircraft that is tied in with its SPRINT and HSVTOL work, and that you can read more about here. Bell previously teamed with Boeing to develop the V-22 Osprey tilt-rotor, variants of which are in service with AFSOC, as well as with the Marines and U.S. Navy.
The Air Force and Marine Corps, as well as the U.S. Army, have already been exploring smaller uncrewed vertical takeoff and landing-capable drones to support logistics requirements and other mission sets. The Air Force has been experimenting with light fixed-wing aircraft converted into drones as small uncrewed airlifters, as well.
It does still remains to be seen whether a working design of any kind emerges from SPRINT, HSVTOL, or NGIA. If one does, whether it actually enters operational service with the Air Force or any other branch of the U.S. military is also an open question.
“There’s a lot of hard things,” AFOSC head Lt. Gen. Conley said at the AFA conference last month again while speaking about SPRINT and HSVTOL. “Some of it’s just the technological pieces of the engines and trying to get enough lift and enough size.”
“I think, conceptually as an Air Force, we struggle a little bit with how big is big enough … as you look at the developmental models, some of them are, you know, the size of a sedan. And then… another iteration would be the size of about a UH-60 [Black Hawk helicopter]. And then you get up to a little bigger … probably C-130 ‘lite,'” he continued. “And I think as an Air Force that’s used to move in a lot of big things, and a lot of people, and a lot of pallets, and big amounts of cargo, there’s a little bit of a mental block there.”
Conley’s general sentiments here have been echoed by other Air Force officials in the past.
“There were … thousands, maybe, of C-47s, and they were all over the Pacific [during World War II],” Gen. Kenneth Wilsbach, then head of U.S. Pacific Air Forces (PACAF), said back in 2022. “They weren’t fast, but they can carry a lot, and they tackled the logistics problem of the Pacific by having a lot of tails to … move equipment.”
Although “it got there at 120, maybe 150 knots … it worked,” he added. “We could have something like that … where you don’t have to have it going 500 knots,” but the logistics effort wouldn’t “eat a lot of tail numbers to be able to get the small bits of equipment and pieces to the various spots that we intend to deploy from.”
“Does it have to be manned? Can it be unmanned? Does it have to be 10,000 pounds or 5,000 pounds [payload capacity-wise]? Can I do vertical lift? Can I do it on an airship [or] a slow-moving low-altitude blimp?” now-retired Gen. Mike Minihan, then head of Air Mobility Command, asked rhetorically while speaking about future airlift requirements in an interview with Aviation Week last year. “There’s a lot of opportunity when it comes to how you approach that.”
It is worth remembering here that the Air Force did briefly operate a fleet of C-27J Spartan cargo aircraft between 2008 and 2013. Those aircraft had been acquired specifically to support intra-theater airlift requirements as part of what was originally a joint program with the Army. The Air Force ultimately curtailed those plans ostensibly due to budgetary limitations and divested all of its Spartans. Some of those C-27Js subsequently ended up in the Army’s special operations aviation inventory.
SOCOM and AFSOC have clear interest currently in seeing SPRINT and HSVTOL through to the delivery of an operational capability. Aurora’s latest renderings show how that work could further evolve into designs to support a wider array of mission sets.
Contact the author: joe@twz.com