Historically speaking, Piasecki Aircraft is no stranger to designing aircraft that challenge the current mainstays of aviation, specifically in the world of rotorcraft. Enjoying a ton of popularity in the 1950s and early 1960s, Piasecki receded into the shadows for a while, occasionally popping out to unveil a few dramatically insane heavy lift ideas that never actually amounted to anything. Today, they’re back with a new take on one of the most successful utility helicopter systems in history- the UH-60 Black Hawk.
Piasecki was loaned a Sikorsky YSH-60F Sea Hawk (the Navy’s version of the UH-60) expressly for modification as part of the Vectored Thrust Ducted Propeller Compound Helicopter Program, which serves to demonstrate the potential for improving Army Aviation’s rotary fleets in terms of endurance, range, combat survivability and speed. The program initially began under the auspices of the US Navy’s Naval Air Systems Command, but changed hands to the Army in 2004. Armed with a concept from its past, the bright minds at Piasecki got to work on deconstructing and reconstructing the airframe in its entirety, replacing components while adhering to strict weight and performance regulations imposed on the program.
The aforementioned concept from Piasecki’s earlier attempts at building a compound helicopter with well-formed speed capabilities was the 16H Pathfinder, another result of a military project spearheaded by the Army and the Navy to provide in-flight data on aircraft of the type (i.e. compound helos) at high speeds. The 16H used a ducted pusher-type fan and a three-bladed main rotor, both linked up to a single General Electric T58 (used by helos such as the SH-2 Seasprite, SH-3 Sea King and the CH-46 Sea Knight) to push it to speeds up to 230 miles per hour. Stability and added maneuverability came with a set of horizontal stabilizers set low at the fuselage’s midsection. Conversely, the Army’s then-new utility helo, the Bell UH-1 Iroquois, could only reach 135 miles per hour at most. Ever since the 16H’s parent program ended, Piasecki retained a portion of the the development team that worked on the Pathfinder prototype, continually progressing the design though only on paper. Eventually, Piasecki had the chance to apply all the lessons learned with the Pathfinder to their new gig with the Army. However, instead of creating a tailor-made aircraft from the ground up, they have to instead customize an existing aircraft, which isn’t necessarily the easiest thing to do.
The result was something similar to the original Kiowa life extension/modification proposal from AVX Aircraft Company. To increase speed, the traditional tail boom with a secondary rotor gets replaced with a ducted pusher-type propeller, also contributing to an increase in in-flight stability, not that it’s a constant problem that needs to be addressed anyway. The cockpit wasn’t greatly redesigned, but a fly-by-wire control system was added to reduce pilot workload, and to take greater advantage of the thrust vectoring provided by the pusher fan in the rear. Externally, the aircraft retained a passing resemblance to the Sea Hawk that it once was, though it now sports a set of forward-swept wings, an extended cabin and the big fan on the rear. Dubbed the X-49 SpeedHawk, it certainly lives up to its name. Thanks to the lift generated by the wings, a significant load is removed from the main rotor, allowing for a 50% increase in forward speed. The entire airframe now being optimized for speed means that the landing gear retracts into the fuselage, and unnecessary protrusions are minimized. The reduced rotor load also increases the range and extends the life of the aircraft. The Army will likely never procure the SpeedHawk modification package, especially since the X-49A was only modified for testing and research purposes. However, the Sikorsky S-97 Raider, another compound helo (though purpose-built as such) might just be the aircraft the Army buys instead. Sikorsky aims to market it in the special operations role, especially highlighting its noticeably decreased sound profile, incredible speed (253 mph) and its maneuverability and versatility. Like the SpeedHawk, the Raider has a pusher prop in the rear, though it isn’t enclosed in a duct-type setup with vectoring panels.