The US Air Force (USAF), in partnership with the US Special Operations Command (USSOCOM), initiated the “High-Speed Vertical Take-Off and Landing (HSVTOL) Concept Challenge” in April (see “Industry Briefs,” Vertiflite, July/Aug 2021). According to the USAF’s AFWERX unit, “The near-term challenge goal is to produce an HSVTOL conceptual framework that maximizes the trade space of speed, range, survivability, payload, size, and flexibility to carry out missions across the full spectrum of conflict and political scenarios. Critical mission profiles include Infiltration and Exfiltration of Special Operations Forces (SOF) and Equipment; Personnel Recovery; Aeromedical Evacuation; and Tactical Mobility.” A key feature of the HSVTOL Challenge is the amount of publically available information in order to encourage collaboration and “crowdsourcing” complementary ideas and technologies.
A total of 218 proposals were submitted entries, with 35 solutions selected for further discussion. According to Aviation Week (“AFWerx Challenge Showcases High-Speed VTOL Concepts,” Aug. 3), two dozen were focused on aircraft designs (see table below), with the remaining 11 being system technologies (such as improvements to engines, materials or radars). The 35 selected responses were presented to the USAF in mid-August and may receive funding for further research, development and testing, with the potential for future procurement contracts for production and fielding. Four companies made announcements in early August that they had been selected and provided additional insights, as detailed below.
Advanced Tactics and Rotor X
Torrance, California-based Advanced Tactics, Inc., (AT) announced its Barracuda line of tilting rotor concepts, which it said would be scalable from 30 lb (14 kg) to 200,000 (90 metric tons) for military and commercial applications. Advanced Tactics teamed with Chandler, Arizona-based Rotor X Aircraft Manufacturing Co. (see “EAA AirVenture 2021’s Vertical Flight & Electric Aviation Trajectory,” pg. XX, and “Industry Briefs: Rotor X Acquires RotorWay,” Vertiflite, March/April 2021) — both owned by the same CEO, Donald Shaw — and is supported by Georgia Tech for computational fluid dynamics (CFD) analysis.
According to the company’s press release, the aircraft design for the USAF HSVTOL program was designed for a useful load of 12,500 lb (5.7 t) — or 14 seats (crew and passengers) — with a cruise speed above 400 kt (740 km/h) and a fully loaded VTOL range of more than 2,400 nm (4,450 km) or a short takeoff and landing (STOL) range of more than 3,200 nm (5,900 km). It also can cruise on a single engine and make an emergency landing with only half-power, low downwash and no cross-shafting necessary due to this redundancy. The company press release noted that “AT is the technology developer providing over 14 years of innovation of next-generation vertical lift aircraft, and over 10 years of Barracuda technology testing. Rotor X, a company with over 50 years of helicopter manufacturing experience, will be the primary manufacturer for all the components of the Barracuda. The AT/Rotor X team will jointly assemble and test the Barracuda prototypes.”
The company said it also designs for the Barracuda HSVTOL family of aircraft suited to missions such as long-range, runway-independent commuter and air-taxi service, industrial and mining logistics, humanitarian assistance and disaster relief, maritime patrol and rescue.
Bell unveiled its folding tiltrotor approach for design concepts ranging from 4,000 lb (1.8 t) to more than 100,000 lb (45 t) with “scalability to the range of missions from unmanned personnel recovery to tactical mobility. The basic propulsion architecture is similar to the Bell Boeing Folding Advanced Stopped TiltRotor (FASTR) DARPA project in 2009 and previous studies going back to the 1960s. Bell tested a 25-ft (7.6-m) diameter stop/fold tiltrotor semi-span in cruise mode in the NASA Ames full-scale wind tunnel in 1972.
Of its current design, Bell said its “HSVTOL technology blends the hover capability of a helicopter with the speed, range and survivability features of a fighter aircraft.” The company highlighted its low downwash hover capability, jet-like cruise speeds over 400 kt (740 km/h), runway independence and hover endurance.
Industry sources indicate that Bell’s folding tiltrotor approach was an early concept for what was then being called “Agility Prime,” prior to that program becoming the USAF electric VTOL initiative under Dr. Will Roper, then Assistant Secretary of the Air Force for Acquisition, Technology and Logistics.
In addition, Edmonds, Washington-based Jetoptera — which has flown a series of small-scale aircraft over the past three years using fluidic thrust vectoring for VTOL flight — teamed with Northrop Grumman’s Scaled Composites and was also selected to proceed to the next phase for HSVTOL. The company is proposing a fluidic propulsive system (FPS) blending-wing body (BWB) concept called “Hedwig.”
In March, the company announced that it had been awarded two Small Business Technology Transfer (STTR) contracts from the USAF (1) to further characterize the noise of its FPS in an anechoic chamber wind tunnel, and (2) to prove that using the FPS with upper surface blowing (USB) on the wing will produce specific lift force levels similar to those of a rotorcraft, but without moving parts. Jetoptera partnered with the University of Notre Dame and University of Washington, respectively, for the two six-month contracts.
Los Angeles, California-based JetPack has been developing its turbine engine-powered VTOL backpack technology for more than a decade. In 2016, company CEO David Mayman famously flew its JB9 JetPack around the Statue of Liberty.
Since August 2018, the company has also been focused on developing its Speeder aircraft for military and civil use, first flying a one-third scale prototype, followed by a full-scale (P1.0) tethered hover test bed in July. Flight test of P1.5, the second full-scale prototype, is expected to begin this fall. Aircraft P2 — featuring a fully formed body; small, field-removable wings; and forward canards — should fly in early 2022.
JetPack Aviation said its Speeder is well suited to satisfy the USSOCOM missions. Powered by small, gimballed turbojet engines, the Speeder reaches speeds approaching 300 mph (260 kt or 480 km/h) with “a payload capability currently available only from considerably larger helicopter airframes. The Speeder’s footprint is also considerably reduced. It has no rotors, ducted fans, or propellers, which reduces/negates the need for specific ground infrastructure.”
Easily transportable in a car or motorcycle trailer, and immediately ready to fly, with no charging or other aviation infrastructure requirements, the Speeder offers high-speed forward flight with control and lift effected by aerodynamic surfaces as required, building on the aircraft’s ability to fly on engine thrust vectoring, the company said. The Speeder is modular, offering a variety of missionized payloads, optionally piloted and simple enough to operate and maintain under austere field conditions. “The aircraft burns regular Jet A-1, kerosene, or diesel, but in a recent cooperative supply agreement with Prometheus Fuels Inc., JetPack Aviation has committed to using 100-percent zero-net carbon fuel in all its own future operations.”
According to Mayman, selection to participate in the AFWERX Challenge “demonstrates that developing the Speeder concept to deliver immediate, multi-purpose applications is relevant to today’s military forces.”
Aircraft Concepts Selected for the HSVTOL Challenge Showcase
AirShip Technologies Group
AIRSHIP VX, 520-kt fan-in-wing
Lip Wing, a combination canard/lip-wing and channel-wing design
American Aerospace Engineering
Eversor, 450-kt, jet-powered tandem-tiltwing
Black Shadow, four compact lift engines and two conventional turbofans for 450-kt cruise
Cavorite X5, hybrid-electric lift-plus-cruise with multiple distributed lift fans embedded in wing and foreplane
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