so you can take off and land vertically

The annual research and development budget of the United States Department of Defense amounts to 132.417 million euros, exceeding the annual allocation of Spain, France, Germany and the United States. Italy united. This amount of money translates into the promotion of projects of all kinds, including some that seek to go beyond conventional combat aircraft.

Of all the participating agencies, DARPA emerged as the most advanced and disruptive agencies. One of the latest is the project to create Aircraft with technologies independent of speed and runwayknown by its acronym in English SPRINT, which is carried out in collaboration with the United States Special Operations Command.

“The goal is design, build and fly an experimental aircraft to demonstrate key technologies and integrated concepts that allow a transformative combination of aircraft speed, capable of operating on any type of runway and which, in addition, achieves high flight speed, highlights DARPA. These two factors constitute two of the most complicated challenges to overcome. for the aviation industry, where traditionally vertical take-off aircraft have reduced internal cargo space and are slow, except in the case of fighters.

This is the SPRINT project

For DARPA, SPRINT seeks to provide these aircraft with the ability to fly at speeds of between 740 and 833 kilometers per hour at relevant altitudes and also that of “floating in austere environments from unprepared surfaces”. The program entered Phase 1 on November 1, 2023, and as of May 2024, two companies – Aurora Flight Sciences and Bell Textron – have been awarded contracts for Phase 1B. “Companies have approximately one year to complete their preliminary design work on their aircraft.”

Just a few days ago, Aurora Flight Sciences, a Boeing-owned company, released its progress on its aircraft proposal for the SPRINT program. The experimental aircraft uses a wing-integrated propulsion system to provide high-speed, lane-independent mobility in challenging environments.

Also includes a vertical takeoff patternas used by some fighters, which feature “scalable technology for aerial logistics and personnel recovery missions in locations without a prepared runway.”

“Aurora and Boeing are collaborating to develop key technologies that combine to deliver a revolutionary solution to the problem mobility challenges in contested environments and on distributed military bases“, they emphasize from the company. Fan-in-wing (FIW, or motors integrated into the wings) technology “combines an integrated lift fan […] to enable vertical lift agility without sacrificing the payload capacity and aerodynamic efficiency associated with today’s fixed-wing aircraft.

The SPRINT team is designing an unmanned demonstrator with a wingspan of 13.7 meters and a payload capacity of 453 kilograms. As for the propulsion system, engineers incorporated a standard turbojet and turbojet engine that would propel the vehicle at a speed maximum real speed of 833 km/hthe same ones that DARPA believes will meet the requirements of its project.

The technology demonstrated on the SPRINT X aircraft could be extended to medium- and heavy-lift aircraft, creating a future family of complete systems. For example, Aurora imagines a Piloted aircraft with a wingspan of 40 meters and equipped with four engines turbojet for takeoff as well as a 12 meter compartment.

“The FIW plane could match or exceed typical payloads, ranges and speeds of military transport aircraft fixed-wing aircraft, while providing the tactical advantage of vertical takeoff and landing (VTOL), explains Aurora Flight Science. To put things into perspective, it would be like combining the interior cargo capacity of an Airbus A400M with the uniqueness of being able to transport a fixed-wing aircraft. operate in very restricted areas thanks to its VTOL capabilities.

The SPRINT program “provides the opportunity to deliver a game-changing capability to the warfighter,” said Mike Caimona, president and CEO of Aurora. “He high-speed, stealthy, track-independent transportation could help ensure the safety and effectiveness of warfighters in contested environments, so that no area is beyond the reach of the U.S. military.

Earlier this year, the team completed the first of three major test events planned for the current phase of the SPRINT program and with the aim of demonstrating the technological feasibility of FIW. The ground effect test, carried out using a 1.4 meter wingspan model equipped with three turbojets for lift.

The test showed that “the suction effects created by the hover thrusters were negligible” and that the landing gear is configured at the appropriate height to minimize adverse pitching moments that form during hover operations. ground. THE Wind tunnel tests are planned for the end of 2024 and early 2025.

These include a stability and control test using a 2.5 meter wingspan model aircraft and a integrated lift thruster to model aerodynamic effects. The current phase of the program continues until May 2025, with a preliminary design review planned for April of that year. As for flight tests, Aurora says they are planned for 2027.

Bell’s proposal

At the same time, the American company Dell is working on High-Speed ​​​​Vertical Takeoff and Landing (HSVTOL) technology which is integrated into the DARPA SPRINT program and Special Operations Command. In early 2024, the company released a video showing some of the features of its platform, with a much more conservative approach than Aurora’s proposal.

The Bell plane file goes through use a pair of tilt motors in true V-22 Osprey style. This technology transforms the platform into a helicopter when it needs to take off or land and, after the maneuver, the propellers rotate to place themselves in horizontal forward mode, like any traditional aircraft.

In one of the latest videos released on the subject, Bell shows the thrusters mounted on a track-mounted test stand while some thrust generated by the propellers is applied. The aim of this test is simulate propeller operation in a takeoff situation in a tilt-rotor aircraft like the aforementioned Osprey.

“Passing the sled test is the highlight of the investigation [del proyecto] Bell’s HSVTOL and unprecedented technology development,” said Jason Hurst, the company’s executive vice president of engineering. “The technology demonstration provides Bell with crucial experience and knowledge that will serve as basis for the development of our experimental aircraft for the SPRINT program from DARPA. “This is a critical step in creating the next generation of high-speed vertical lift aircraft for future fighters.”