Sikorsky’s high-speed X2 technology faced off against Bell’s proven low-risk approach in the competition to replace the retired OH-58 Kiowa Warrior
The U.S. Army’s Future Attack Reconnaissance Aircraft (FARA) program represented a revolutionary approach to developing next-generation attack reconnaissance capabilities. Nearly a decade before the competition, the US Army had retired its last helicopter designed specifically for the attack reconnaissance mission – the OH-58 Kiowa Warrior. Since then, a combination of AH-64 Apache helicopters and unmanned aerial vehicles (UAVs) filled in, performing the attack reconnaissance mission as best they could.
But near-peer threats demanded next-generation aircraft specially designed to stay ahead of the fight through continuous evolution. Unlike the Kiowa Warrior, FARA was envisioned as Army Aviation’s top modernization priority – a Division, Corps, and Joint Forces-level strategic asset operating deep in the battlespace, delivering deep reach with a level of survivability never before obtained in Army Aviation.
Sikorsky RAIDER X: Speed Through X2 Technology
On October 14, 2019, Sikorsky, a Lockheed Martin company, introduced RAIDER X, its concept for an agile, lethal, and survivable compound coaxial helicopter specifically designed for securing vertical lift dominance against evolving peer and near-peer threats on the future battlefield.
“RAIDER X converges everything we’ve learned in years of developing, testing, and refining X2 Technology and delivers warfighters a dominant, survivable, and intelligent system that will excel in tomorrow’s battlespace where aviation overmatch is critical,” said Frank St. John, executive vice president of Lockheed Martin Rotary and Mission Systems at the time. “The X2 Technology family of aircraft is a low-risk solution and is scalable based on our customers’ requirements.”
The X2 Advantage
X2 technology, the foundation of Sikorsky’s coaxial rotorcraft design, enabled RAIDER X to fly faster and farther than single main rotor helicopters while carrying a significant payload. The speed, range, and integrated mission systems of RAIDER X made it an especially effective strategic asset for the vast expanses of the Indo-Pacific region.
X2 designs also allowed for inherent growth of the weapon system compared to the limitations of single-main-rotor aircraft. By the time of RAIDER X’s introduction, X2 aircraft had already demonstrated impressive capabilities:
- Speeds over 250 knots
- High-altitude operations over 9,000 feet
- Low-speed and high-speed maneuver envelopes out to 60+ degrees of angle of bank
- ADS-33B (Aeronautical Design Standard) Level 1 handling qualities with multiple pilots
- Flight control optimization and vibration mitigation
“The power of X2 is game-changing. It combines the best elements of low-speed helicopter performance with the cruise performance of an airplane,” said Sikorsky experimental test pilot Bill Fell, a retired Army pilot who flew nearly every RAIDER test flight. “Every flight we take in our S-97 RAIDER today reduces risk and optimizes our FARA prototype, RAIDER X.”
RAIDER X’s Mission Profile
Flying low and fast to stay hidden below the tree line, RAIDER X was designed to deliver crucial intelligence and keep forces connected through a secure mesh network. Built to find, fix, and finish anti-access/anti-denial (A2AD) and enemy forces, RAIDER X would operate in contested environments at the front of the fight as a sophisticated sensor, central network hub, and powerful armed reconnaissance helicopter all in one.
“RAIDER X is a complete weapon system,” said Jay Macklin, Sikorsky’s director of Future Vertical Lift Business Development and a retired Army Aviator, in a Sikorsky news release. “It provides significant reach, survivability, and lethality – much more than exists with today’s enduring fleet. RAIDER X will be plugged into the network as a key part of the combined arms force, enabling the ground commander to see and shape the battlefield.”
With its low- and high-speed maneuverability, RAIDER X excelled in the lower-tier air domain (LTAD) – the space between the ground and 100 feet. It was envisioned as a networked sensor package supporting the joint domain, significantly extending the battle area’s boundaries by scouting, coordinating, and providing feedback through the management and sustainment of Launched Effects (LE) networks at the tactical edge.
Key Features of RAIDER X
Sikorsky’s prototype offered several compelling advantages:
Exceptional Performance: The X2 rigid rotor provided increased performance, including highly responsive maneuverability, enhanced low-speed hover, off-axis hover, and level acceleration and braking.
Agile, Digital Design: State-of-the-art digital design and manufacturing already in use on other Lockheed Martin and Sikorsky production programs, such as CH-53K, CH-148, and F-35, would enable the Army to not only lower acquisition costs but also enable rapid, affordable upgrades to stay ahead of evolving threats.
Adaptability: Modern open systems architecture (MOSA)-based avionics and mission systems offered “plug-and-play” options for computing, sensors, survivability, and weapons, benefiting lethality and survivability, operational mission tailoring, and competitive acquisitions.
Sustainable Maintenance: Designed to decrease aircraft operating costs by utilizing new technologies to shift from routine maintenance and inspections to self-monitoring and condition-based maintenance, increasing aircraft availability and reducing sustainment footprint.
Growth/Mission Flexibility: X2 compound coaxial technology provided unmatched potential and growth margin for increased speed, combat radius, and payload, enabling operational mission flexibility with a broader range of aircraft configurations and load-outs.
“RAIDER X is the culmination of decades of development, and a testament to our innovation and passion for solving our customers’ needs,” said Sikorsky President Dan Schultz. “By leveraging the strength of the entire Lockheed Martin Corporation, we will deliver the only solution that gives the U.S. Army the superiority needed to meet its mission requirements.”
Bell 360 Invictus: Proven Technology, New Application
On October 2, 2019, Bell Textron announced its entrant for FARA: the Bell 360 Invictus. Bell’s innovative approach combined proven low-risk technologies with advanced processes to deliver soldiers an affordable, agile, and lethal solution for the modern battlefield.
“The Bell 360 will deliver advanced battlefield situational awareness, as well as lethal options, in support of the maneuver force at an affordable cost,” said Vince Tobin, executive vice president of Military Business at Bell, in the company news release. “The multi-domain fight will be complex, and our team is delivering a highly capable, low-risk solution to confidently meet operational requirements with a sustainable fleet.”
Design Philosophy
The Bell 360 Invictus’ design emphasized exceptional performance using proven technologies to fulfill the Army’s FARA requirements at an affordable cost and on schedule. A prime example was the Invictus’ rotor system, based on Bell’s 525 Relentless rotor system, which had been tested and proven at speeds exceeding 200 Knots True Air Speed (KTAS). By incorporating proven designs and the best available technologies from commercial and military programs, Bell offered a low-risk path to a FARA program of record.
“Bell is committed to providing the U.S. Army with the most affordable, most sustainable, least complex, and lowest risk solution among the potential FARA configurations while meeting all requirements,” said Keith Flail, vice president of Advanced Vertical Lift Systems at Bell. “360 Invictus is an exciting opportunity for us to continue our support of Army modernization. This is the next solution to ensure soldiers have the best equipment available for the multi-domain fight.”
Key Features of the 360 Invictus
The advanced aircraft was designed to have a transformative impact through next-generation flight performance, increased safety, and greater operational readiness:
Design-as-built manufacturing model and digital thread-enabled tools to enhance affordability, reliability, and training
- Lift-sharing wing to reduce rotor lift demand in forward flight, enabling high-speed maneuverability
- Supplemental Power Unit to increase performance during high power demands
- Robust articulated main rotor with high flapping capability, enabling high-speed flight
- Fly-by-wire flight control system to synthesize technologies, reduce pilot workload, and provide a path to autonomous flight
- Speed: >185 KTAS
- Combat radius: 135nm with >90 minutes on station
- 4k/95F Hover Out of Ground Effect (HOGE) capability
- Armed with a 20mm cannon, an integrated munitions launcher with the ability to integrate air-launched effects and future weapons
- Provisioned for enhanced situational awareness and sensor technologies
- Modular Open Systems Approach (MOSA) enabled by a Digital Backbone from Collins Aerospace
- Robust design integrating lifecycle supportability processes to ensure high OPTEMPO availability
- Design-as-built manufacturing model and digital thread-enabled tools to enhance affordability, reliability, and training
Legacy and Experience
Bell had decades of experience providing attack and reconnaissance aircraft to the warfighter, including the Kiowa Warrior, which delivered high reliability and availability through more than 850,000 flight hours. The Bell 360 Invictus design built from that legacy, Bell’s commercial innovations, and the success in development and manufacturing capabilities required for Future Vertical Lift (FVL) as part of the Joint Multi-Role Technology Demonstration (JMR TD).
The FARA Competition
Both competitors brought compelling but distinctly different approaches to the FARA competition. Sikorsky leveraged its revolutionary X2 coaxial rotor technology for superior speed and maneuverability, while Bell emphasized proven systems and affordability through adaptation of existing commercial and military technologies.
The development of X2 Technology and the RAIDER program had been funded entirely by significant investments by Sikorsky, Lockheed Martin, and industry partners, demonstrating the company’s commitment to the technology. Both teams assembled nationwide supply chains and drew on their parent corporations’ extensive resources and expertise.
With an increasingly complex future threat environment and swift pace of technological change, both designs emphasized the Army’s Modular Open Systems Approach (MOSA), providing leap-ahead capability and enabling rapid upgrades. This adaptability was seen as the starting point for decades of innovation, merging superior physical performance with transformational digital capabilities to help warfighters meet the challenges of tomorrow’s multi-domain missions.
Photos by Sikorsky / Lockheed Martin and Bell
