Sikorsky's S-97 Raider Compound Helicopter Has Been Cloned By China

Just three days after imagery surfaced of China's first known crewed tiltrotor aircraft taking to the air, we have gotten our first sight of a previously unknown compound coaxial helicopter. The aircraft, whose designation remains unknown, is now undergoing test flights and is a direct clone of the U.S.-made Sikorsky S-97 Raider.

The development confirms that China, too, is looking at harnessing the benefits of this kind of aircraft, which offers much higher speeds than a conventional helicopter, as well as increased maneuverability. The images showing the new compound coaxial helicopter emerged today, apparently first being posted to China's Weibo microblogging site. They show the rotorcraft in flight and immediately betray its close connection to the S-97.

The Chinese design adopts the same propulsion configuration, with four-blade coaxial main rotors – which looks like a rigid design – and a pusher propeller. The Chinese aircraft appears to be of almost identical size and also has the same 'tadpole'-like fuselage shape and landing gear configuration. Like the S-97, the Chinese helicopter also has a relatively large, plank-like horizontal tail with endplate tailfins.

However, the tailfin design is different, with the larger part of the fin projecting above the tailplane, rather than below it. At this point, it's worth recalling that this is far from the first Chinese design to share a significant superficial resemblance to a Western aircraft. In the rotary field, the Harbin Z-20 helicopter is widely regarded as a Chinese clone of the H-60/S-70 Black Hawk/Seahawk, while the Chinese FH-97 drone looks like a carbon copy of the XQ-58A Valkyrie.

These are just two examples, and while accusations of simply aping existing Western designs are an oversimplification, China has been accused on multiple occasions of hacking detailed design information from U.S. aerospace defense contractors. Regardless of what kinds of Western technologies may have been exploited for its new compound coaxial helicopter, it's interesting that China is now making a foray into this field and that it's following the established S-97 design so closely.

Sikorsky's S-97 prototype, which is a descendant of the same company's X-2 and X-49 demonstrators, was developed as an 80-percent surrogate for the larger Raider X and weighed around 14,000 pounds. In tests, the helicopter has achieved speeds in excess of 200 knots, well beyond the top speeds of conventional rotorcraft.

While the Raider X has a more pointed nose and a reversed landing gear arrangement, the aircraft were otherwise essentially very similar in form. The Raider X was Sikorsky's pitch for the U.S. Army's Future Attack Reconnaissance Aircraft (FARA) program, in which it went up against Bell's 360 Invictus, a conventional single-main-rotor helicopter with a canted tail rotor.

FARA was conceived as filling the armed scout role vacated by the retirement of the OH-58D Kiowa Warrior. That mission was then performed by RQ-7 Shadow and MQ-1C Gray Eagle drones teamed with AH-64 Apache attack helicopters. While it was expected that FARA could replace a significant number of AH-64s currently in the Army's inventory, the program was axed in early 2024.

Central to the compound coaxial configuration of the S-97/Raider X (and now the analogous Chinese rotorcraft) is the pusher prop in the tail and the rigid, contrarotating rotors that eliminate the need for a tail rotor. The pusher prop allows for bursts of speed and rapid deceleration, increased maneuverability, and a higher sustained cruise speed.

Range will also be increased compared to a standard helicopter, although not to such an extent as a tiltrotor. Unlike a conventional helicopter, a compound coaxial like this can fly forward with its nose up or backward with its nose pointed at the ground, while the Raider has routinely demonstrated an ability to 'pirouette' nose-down around a single point.

These compound coaxial helicopters can also fly at top speed while maintaining a level attitude, compared to a regular helicopter that has to point its nose down to accelerate forward. In forward flight, the pusher prop can be activated, and the spinning rotors are slowed to act more like wings than rotors, reducing drag and boosting speed and efficiency.

Essentially, unlike a standard helicopter where the blades create lift during only part of their rotation, the rotor blades generate lift on both sides of the aircraft as they spin. Speed is very far from a promise of immunity to battlefield threats, but it is certainly a valuable enhancement.

It translates to reduced exposure to threats, including traditional ground fire, with less reaction time for the enemy to make a successful engagement. Other advantages of speed include reduced transit times to combat areas and the possibility of escaping certain threats with a high-speed dash.

The PLA's Interest in Rotary Technologies

The Chinese People's Liberation Army (PLA) is keenly aware of the need to maintain wartime operations without access to conventional airstrips, and helicopters would play a fundamental part in this. China also has access to a growing fleet of amphibious assault ships that would be ideal platforms for hosting advanced rotorcraft.

China is looking at the potential of tiltrotor designs that can be either crewed or uncrewed, alongside crewed helicopters in a mutually beneficial force mix. Already, it is looking at the potential of uncrewed air systems to play a hugely important role on the battlefield.

A Complicated Battlefield Landscape

Amid concerns around survivability, the relevance of rotorcraft is now a major point of discussion, fueled by emerging lessons from both sides of the war in Ukraine. In this theater, conventional rotorcraft have suffered greatly, especially at the hands of forces armed with man-portable air defense weapons (MANPADS), while lower-end drones are also a fast-emerging threat.

However, the situation is a little different for China, which would be better able to preposition its rotary assets ahead of a conflict and support assets, spares, and other parts of the logistics trail. Even in peacetime, China has a significant requirement to deliver cargoes to remote locations, including island outposts in the South China Sea.

China is keenly aware of the need to maintain wartime operations without access to conventional airstrips, and helicopters would play a fundamental part in this. However, even with the additional speed and agility that a compound coaxial offers, helicopters of any kind remain vulnerable when operating on a modern battlefield, with its layered air defenses.

When it comes to the attack and reconnaissance roles, survivability increasingly depends on the respective ranges between the helicopter and its target. With that in mind, the kinds of weapons and sensors that production versions of China's next-generation rotorcraft might field are just as important as the airframes themselves.

A New Frontier for Rotary Technologies

At this point, there are more questions than answers about China's new compound coaxial helicopter, with a lack of clarity about its intended role as well as its design authority. However, it's notable in itself that China is now exploring rotary technologies that should allow speeds of close to double that of conventional helicopters.

Even though Sikorsky says it still has hopes for its X-2 technology, it would be highly ironic if its potential ends up being exploited by America's top pacing threat, China. The development confirms that China is serious about embracing compound coaxial rotorcraft as a key component of its military strategy.

The future balance between crewed rotorcraft and different kinds of uncrewed aircraft on the battlefield will likely be a complex one to navigate. But for now, it's clear that China sees its new compound coaxial helicopter as an important step towards realizing its goals in this area.