New Vision for Lift Fan Aircraft Family

• The concept depends on a successful Aurora bid.
• The new design appears to diminish some stealthy features and enhance others.
• The revised render showcases streamlined intakes for the main engines underneath the body.

Aurora Flight Sciences has recently unveiled updated visual representations of an unmanned fan-in-wing vertical take-off-and-landing demonstrator aircraft as well as a revised concept for an enlarged cargo aircraft based on the same technology. These developments are part of the company’s involvement in the Defence Advanced Research Projects Agency (DARPA) program known as Speed and Runway Independent Technologies (SPRINT), which aims to produce an X-plane demonstrating essential technologies and integrated concepts enabling a transformative combination of aircraft speed and runway independence.

Aurora's design aims to meet or exceed the challenging program objectives set by DARPA. Notably, the blended wing body platform is capable of a 450-knot cruise speed, and the incorporated lift fans with integrated covers facilitate a seamless transition from vertical to horizontal flight. The design also leverages existing engine solutions, reducing development risks and timelines. Additionally, the aircraft is capable of various take-off and landing modes, including vertical take-off and landing (VTOL), short take-off and vertical landing (STOVL), super short take-off and landing (SSTOL), and conventional take-off and landing.

The company is collaborating with Boeing on the development of key technologies to address mobility challenges in contested environments and across distributed military bases. The fan-in-wing (FIW) technology combines an embedded lift fan with a blended wing body design, enabling vertical lift agility without sacrificing payload capacity and aerodynamic efficiency associated with today’s fixed-wing aircraft.

The updated rendering of the SPRINT demonstrator is consistent with the previously released version, featuring a blended-wing platform with a V-tail and three lift fans arranged in a triangular configuration. The revised render showcases streamlined intakes for the main engines underneath the body.

In addition, Aurora reports the completion of the first of three major test events scheduled for the current phase of the SPRINT program earlier this year. This test, conducted using a 4.6-ft wingspan model with three lift fans, demonstrated the feasibility of the FIW technology, with negligible suck-down effects created by the lift fans in hover and appropriate landing gear height to minimise adverse pitching moments during ground operations. Further wind tunnel tests are planned for late 2024 and early 2025 to model aerodynamic effects.

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 a 40-ft payload bay. This 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 take-off and landing.

The newly released rendering of the larger fan-in-wing design concept from Aurora features significant changes from the 2023 version, including a tailless modified cranked kite platform with lower profile air intakes on top of the rear end of the central body. The design still includes four lift fans, two on either side of the central body.

Moreover, the new design appears to diminish some stealthy features and enhance others compared to the 2023 concept. The updated rendering also reveals alterations to the design of the lift fan covers, featuring multi-sectioned covers as opposed to the split covers presented in the previous version.

Aurora’s one-third-scaled prototype calls for a tailed, blended wing body design, with the trailing edge of the wing positioned forward of the fuselage tail. The 45-ft. wingspan includes three lift fans. The top of the fuselage includes two auxiliary inlet doors for airflow in vertical mode. A pair of caret-shaped inlets on either side of the forward fuselage ingests air for a single turbofan engine to provide horizontal thrust. The prototype is being designed to carry a 1,000-lb. Payload.

The operational version of the Boeing-owned company’s candidate for a DARPA demonstrator program would boast nearly the same wingspan and payload weight of a Lockheed Martin C-130J yet fly up to 90 kt. Faster and be able to take off and land vertically like a helicopter.

The Aurora concept includes two turbofan engines for horizontal thrust and four fans embedded into the blended wing body airframe for vertical lift. This “vision” aircraft concept also features cranked outboard wing sections and no vertical tails.

The concept depends on a successful Aurora bid to develop the demonstrator for DARPA’s Speed and Runway Independent Technologies (Sprint). Bell is working on a competing proposal based on a tiltrotor aircraft featuring stop-fold rotor technology.

DARPA’s goal is to achieve a new standard in high-speed flight for transport aircraft with VTOL capabilities. The SPRINT program aims to increase the top speed to 450 knots, building on modern advances in lightweight structures and fly-by-wire flight controls, which could make such high-speed, runway-independent aircraft viable.