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Piasecki X-49 SpeedHawk
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The Piasecki X-49 "SpeedHawk" is an American four-bladed, twin-engined experimental high-speed compound helicopter developed by Piasecki Aircraft. The X-49A is based on the airframe of a Sikorsky YSH-60F Seahawk, but utilizes Piasecki's proprietary vectored thrust ducted propeller (VTDP) design and includes the addition of lifting wings. The concept of the experimental program was to apply the VTDP technology to a production military helicopter to determine any benefit gained through increases in performance or useful load.
Key Information
"SpeedHawk" is a concept aircraft[1] based on applying X-49A compounding concepts to a production UH-60 Black Hawk offering better performance, range, and increases in useful load. The "SpeedHawk" aircraft includes an SPU (third engine), high forward-swept wing concept, a 45-inch "fuselage plug" cabin extension, and several other drag reducing and performance-oriented improvements, including a rotor hub fairing, landing gear streamlining, and a fly-by-wire flight control system.
Development
[edit]The U.S. Navy-sponsored project, worth US$26.1 million when announced in 2003 ($44.6 million today), consisted of a Sikorsky YSH-60F helicopter modified by Piasecki as a testbed to validate the "Vectored Thrust Ducted Propeller" (VTDP) system. One YSH-60F, powered by two General Electric T700-GE-701C engines, was converted to test the feasibility of VTDP.
The demonstration contract was awarded by the Naval Air Systems Command to Piasecki Aircraft. In addition to the VTDP, Piasecki installed a lifting wing with flaperons on the YSH-60F.[2]
The compound helicopter technology installed by Piasecki had been first demonstrated in trials of the Piasecki 16H-1 and 16H-1A “Pathfinder” in the early 1960s, when the helicopters were flown at speeds up to 225 mph (362 km/h). The success of the Pathfinder inspired others to experiment with compounding, resulting in programs such as the AH-56 Cheyenne.
In May 2003, the YSH-60F/VTDP demonstrator was redesignated the X-49A.[3] During 2004, the X-49A VTDP program was transitioned from the U.S. Navy to the U.S. Army.[4]
In 2013, it was reported that Piasecki Aviation had made plans to use the VTDP design of the X-49 for their entry in the Future Vertical Lift program,[5] but were not chosen when that project moved into its Joint Multi-Role Technology Demonstrator (JMR-TD) phase.[6]
Design
[edit]The X-49A flight demonstrator was developed with funding from the U.S. Army's Aviation Applied Technology Directorate to demonstrate the ability to increase the speed of existing helicopters to 200 kn (370 km/h) or more.[7] The flight demonstrator was updated with a lifting wing taken from an Aerostar FJ-100 business jet. A ring tail was added and the helicopter drive train modified to accommodate VTDP. Piasecki conducted integrated tests of the modified drivetrain at the Navy's helicopter transmission test facility. The wings were intended to produce lift to offload the rotor so the rotor could be slowed and produce less drag, allowing for higher speed.[8]
The cockpit controls were modified with the addition of a manual propeller pitch override on the collective lever for the ring tail. This is the only visible change to the aircraft's existing mechanical controls in the cockpit. The other controls needed to operate the compound helicopter's systems were integrated into the aircraft's existing mechanical controls to reduce pilot workload. The weight added to the X-49A demonstrator aircraft is estimated at 1,600 lb (730 kg) due to the requirement[citation needed] to not modify the existing mechanical control system.
Operational history
[edit]The X-49A made its first flight on June 29, 2007[9] for 15 minutes at Boeing's New Castle County (KILG) flight test center.[10] This flight included hovering, pedal turns, and slow forward and sideways flight using the VTDP for anti-torque, directional and trim control. The X-49A project has been silent since completing its initial testing phase in 2008, with over 80 flight events and more than 80 total hours logged.[citation needed]
Specifications (X-49A)
[edit]General characteristics Performance
- Maximum speed: 190 kn (220 mph, 350 km/h)
- Cruise speed: 130 kn (160 mph, 250 km/h)
- Never exceed speed: 220 kn (250 mph, 410 km/h)
- Thrust/weight: 1000
See also
[edit]Related development
Aircraft of comparable role, configuration, and era
Related lists
References
[edit]- ^ ".aviationtoday.com". Archived from the original on 2015-04-02. Retrieved 2007-12-06.
- ^ "Piasecki X-49 SpeedHawk (United States)", Jane's Helicopter Markets and Systems. Jane's Information Group, 9 May 2008.
- ^ DOD 4120.15-L - Addendum, Designation-Systems.Net, 8 July 2008.
- ^ Graham Warwick (2006-01-03). "Funding may block X-49 progress". FlightGlobal.com. Retrieved 2007-07-03.
- ^ The Other JMR/FVL Contenders Archived 2013-05-02 at the Wayback Machine - Aviationweek.com, April 12, 2013
- ^ AVX joins Bell, Sikorsky/Boeing for Army's JMR-TD development - Flightglobal.com, 6 June 2013
- ^ Graham Warwick (2007-07-03). "Piasecki flies X-49A SpeedHawk compound helicopter". FlightGlobal.com. Retrieved 2007-07-03.
- ^ Croft, John. Hyper Helos: Prototypes coming off the drawing board and into the race Flight Global, 2008. Accessed: 17 February 2011.
- ^ "Piasecki Achieves First Flight of the X-49A VTDP Compound Helicopter Technology Demonstrator" Archived 2014-03-14 at the Wayback Machine, Piasecki Aircraft, June 29, 2007.
- ^ "Rotorcraft Report: Piasecki SpeedHawk Starts Flight Tests" Archived 2014-03-14 at the Wayback Machine, Rotor & Wing Magazine, August 1, 2007.
External links
[edit]
Wikimedia Commons has media related to Piasecki X-49.
- Official website
- Jane's All The World's Aircraft - X-49A
- "High Speed Helicopter set for first flight in June" article on FlightGlobal.com
- Rotor and Wing Cover Story Dec 2007 Archived 2015-04-02 at the Wayback Machine
- Vertiflite Cover Story Winter 2007
- Aerospace Testing International Dec 2007 Archived 2008-07-23 at the Wayback Machine
- Boeing Eyes X-49A Technology for Apache Attack Helicopter
- "Hot-Rod Helicopters". Air & Space magazine, 1 September 2009.
- Pushing helicopters faster - X-49A - Aviation Week Video
Piasecki X-49 SpeedHawk
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Development
Program Initiation
The Piasecki X-49 SpeedHawk program originated as a U.S. Navy initiative to explore advanced compound helicopter configurations for enhanced performance in existing rotorcraft fleets. In October 2000, the Naval Air Systems Command (NAVAIR) awarded a demonstration contract valued at $26.1 million to Piasecki Aircraft Corporation, initially as a Small Business Innovation Research (SBIR) Phase I effort, to modify a Sikorsky YSH-60F Seahawk into a technology demonstrator focused on high-speed capabilities.[2] This effort built directly on Piasecki's historical specialization in innovative rotorcraft designs, particularly compound helicopters that integrate fixed-wing elements with rotor systems for improved efficiency.[2][1] The core goals of the program centered on achieving a 50-100% increase in forward speed—targeting up to 200 knots—for platforms like the SH-60 Seahawk, while simultaneously boosting operational range, payload capacity, and agility. These enhancements were intended to address limitations in conventional helicopter performance, such as retreating blade stall at high speeds, without necessitating expensive full-scale redesigns or new production lines. By retrofitting proven airframes, the initiative aimed to provide a scalable upgrade path for naval and army aviation assets, potentially reducing lifecycle costs through lower fatigue loads and improved survivability. The baseline SH-60 Seahawk, with its established cruise speed around 140 knots, served as a reference for measuring these gains.[2][1] Selection of the YSH-60F variant as the testbed was strategic, owing to its structural and systems commonality with the prolific UH-60 Black Hawk and SH-60 Seahawk series, which form the backbone of U.S. rotary-wing operations. This compatibility enabled efficient integration of experimental features while minimizing development risks and costs associated with adapting to unfamiliar platforms. Piasecki's involvement drew on decades of compound helicopter innovation, including vectored thrust ducted propeller (VTDP) concepts refined through exploratory programs in the 1980s, which emphasized auxiliary propulsion for speed augmentation in tandem with main rotors.[2][1][4] The program's Navy sponsorship underscored a broader push for technological maturation of VTDP systems, positioning Piasecki to validate retrofittable solutions that could extend the service life and mission versatility of legacy helicopters. Initial phases focused on conceptual validation and ground testing, setting the stage for flight demonstrations under joint Navy-Army oversight following a 2004 transition to the U.S. Army Aviation Applied Technology Directorate.[2]Modifications and Assembly
The conversion of the baseline Sikorsky YSH-60F Seahawk into the Piasecki X-49A SpeedHawk involved targeted structural modifications to enable compound helicopter capabilities, focusing on enhanced speed and efficiency. A key addition was a 45-inch fuselage plug inserted to extend the cabin space, providing room for auxiliary systems and improving overall airframe balance during high-speed operations.[2] This extension was integrated seamlessly with the existing fuselage structure to maintain structural integrity without compromising the original airframe's load-bearing capacity. To support the vectored thrust ducted propeller (VTDP) system, a supplementary power unit (SPU) was installed as a third engine, utilizing a T63-GE-400 turboshaft mounted within the fuselage.[2] This configuration powered the VTDP while preserving the twin main engines for rotor lift, addressing power distribution challenges inherent in retrofitting an experimental propulsion setup onto a production helicopter airframe. Complementing this, high forward-swept wings with flaperons for lift augmentation and lateral stability were attached, which required precise alignment to the existing pylon structure to avoid aerodynamic interference.[2] Further reinforcements included stiffening the rotor mast and blades to accommodate reduced rotor loading at higher speeds, facilitated by partial off-loading through wing-generated lift.[2] These modifications addressed vibration and stress issues arising from altered load paths in compound flight regimes. The airframe, provided by Sikorsky, underwent modifications and final assembly by Piasecki Aircraft Corporation in 2006-2007, culminating in readiness for testing.[2][5]Design
Airframe and Structure
The Piasecki X-49A SpeedHawk retains the core fuselage structure of the Sikorsky SH-60 Seahawk, a twin-engine naval helicopter, as its foundational airframe to leverage proven durability and operational familiarity. This baseline fuselage, constructed primarily from aluminum alloys, was extended by a 45-inch "plug" section inserted aft of the cockpit to increase internal cargo volume while providing counterbalance for the added mass of the vectored thrust ducted propeller (VTDP) system and associated components, thereby maintaining center-of-gravity equilibrium during compound operations.[6] The four-bladed main rotor system from the SH-60 is preserved unchanged, featuring a diameter of 53 feet 8 inches (16.36 meters) to ensure vertical lift capabilities consistent with the original design.[7] A key structural adaptation is the addition of fixed, forward-swept wings mounted low on the fuselage outboard of the main engines, designed to generate significant supplemental lift in forward flight and reduce loading on the main rotor by up to 50% at cruise speeds, thereby enabling higher velocities without exceeding rotor limits. These wings incorporate in-wing fuel tanks for extended range and hardpoints suitable for armament integration, with their geometry optimized for efficiency to minimize drag and enhance stability.[6] The airframe is powered by the SH-60's twin General Electric T700-GE-401C turboshaft engines, each providing 1,620 shaft horsepower, integrated into the existing nacelles with minimal structural alterations beyond reinforced mounting points to accommodate the auxiliary propulsion drive.[8] To support the demands of compound helicopter operations, the X-49A incorporates fuselage extensions and targeted reinforcements, particularly around the tail boom and landing gear, to withstand elevated forward flight loads and vibratory stresses from the VTDP pusher configuration that replaces the conventional tail rotor. These enhancements include increased rigidity in the tail structure to manage thrust vectoring without a dedicated anti-torque rotor and modifications to the fixed landing gear for improved drag reduction via fairings, while the resulting empty weight is approximately 15,000 pounds through selective use of composite materials in the wing assemblies for weight savings over all-metal construction.[6][2] The structure adds 8-10% to the baseline SH-60 empty weight, reflecting the balance between added lift-generating elements and efficiency gains in high-speed flight.[6]Propulsion and Aerodynamics
The Piasecki X-49 SpeedHawk utilizes a compound helicopter configuration, where the main rotor provides vertical lift and hover capability, while fixed wings generate lift during cruise to offload the rotor. The vectored thrust ducted propeller (VTDP) at the rear supplies forward propulsion, enabling higher speeds by allowing the main rotor to operate at reduced RPM and avoiding retreating blade stall limitations inherent to conventional helicopters. This integration enhances overall efficiency and performance in forward flight without compromising core vertical flight characteristics.[2][9] The VTDP features an 8-foot diameter composite duct enclosing a five-bladed propeller, driven by power transmitted from the aircraft's two General Electric T700-GE-401C turboshaft engines via a hardened driveshaft. In forward flight, the majority of the engines' output—exceeding 2,100 shaft horsepower—can be directed to the VTDP for propulsion, while also serving anti-torque functions in place of a traditional tail rotor. Thrust vectoring is achieved through adjustable vanes and sectors within the duct, allowing directional control and improving yaw authority and efficiency.[10][11][9][12] Aerodynamic enhancements include flaperons on the stub wings for augmented roll and pitch stability, as well as streamlined fairings along the fuselage and tail boom to minimize drag. The VTDP's vectoring capability supports pitch and roll control, derived from similar mechanics in Piasecki's earlier ring-tail designs. This configuration preserves partial autorotation potential on the main rotor for emergency landings, maintaining safe vertical flight profiles despite the compound setup. The wings are structurally integrated with the airframe to support these dynamics seamlessly.[9][13][14]Testing and Operations
Flight Test Program
The Piasecki X-49A SpeedHawk completed its first flight on June 29, 2007, at Boeing's New Castle County Airport in Wilmington, Delaware, successfully validating basic hover performance and low-speed handling characteristics, including pedal turns and forward flight using the vectored thrust ducted propeller (VTDP) for anti-torque, directional, and trim control.[2] This initial 15-minute flight marked the beginning of the experimental program's operational phase, building on the modified Sikorsky YSH-60F airframe to demonstrate compound helicopter enhancements.[5] The flight test program advanced through Phase 1, which focused on progressive envelope expansion, including wing lift-off transitions and full VTDP engagement for augmented thrust and stability, with completion in February 2008 after meeting or exceeding all contract milestones within the standard Seahawk flight limits.[13] Pilots from Piasecki Aircraft conducted the majority of flights, with involvement from Sikorsky representatives due to the shared airframe heritage.[2] The program accumulated 86 flight hours across 79 flights during Phase 1, including evaluations to assess upgrade potential for the Seahawk fleet as part of the initiative aimed at improving speed, range, and survivability.[15] Key challenges addressed during testing included vibration damping in forward flight and control harmonization between the main rotor and VTDP systems, achieving reduced fatigue loads and smoother operation without any reported major incidents.[13] The flight test effort concluded after Phase 1 in 2008, with resulting data archived to inform subsequent compound helicopter developments; no Phase 2 testing was pursued.[2]Performance Results
During flight testing, the Piasecki X-49 SpeedHawk achieved a maximum speed of 177 knots (203 mph) in a slight dive, with level flight speeds around 160-170 knots, representing approximately a 42% increase over the baseline SH-60 Seahawk's cruise speed of 120 knots.[16][17][15] This performance validated the vectored thrust ducted propeller (VTDP) system's ability to enhance forward flight capabilities while adhering to initial contract limits of 175-180 knots.[16] Testing also indicated potential for improved range and endurance, with a projected maximum range of up to 440 miles compared to the baseline, attributed to the wing-borne lift offloading the main rotor during cruise.[3] Hover performance remained near baseline levels, averaging within 3.7% of predicted values, ensuring retained low-speed capabilities.[13] In terms of agility, the X-49 exhibited enhanced maneuverability at high speeds, with the VTDP enabling tighter turns while maintaining cruise speed during maximum performance turnarounds—unlike the SH-60, which experiences up to a 30-knot loss—and requiring only an 8-10° nose-down attitude versus the baseline's 20°.[16] Load-carrying capacity matched the SH-60's 11,200 lb gross weight during tests, with the configuration showing potential for heavier payloads in cruise due to reduced rotor loading.[3] Observed limitations included a transonic drag rise beyond 200 knots, which constrained further speed envelope expansion, and the program did not pursue certification, as the X-49 served solely as a technology demonstrator following completion of Phase 1 testing in 2008.[13]Specifications
General Characteristics
The Piasecki X-49 SpeedHawk accommodates a crew of three and provides capacity for up to 11 troops or equivalent cargo, leveraging the utility configuration of its base SH-60 Seahawk airframe.[7] Its dimensions consist of a fuselage length of 64 ft 10 in (19.76 m), height of 17 ft 4 in (5.28 m), rotor diameter of 53 ft 8 in (16.36 m), and wingspan of 36 ft (10.97 m) incorporating the added forward-swept lifting wings.[18][2] The aircraft has an empty weight of 13,650 lb (6,190 kg) and a maximum takeoff weight of 23,000 lb (10,433 kg), figures comparable to those of the standard SH-60 Seahawk.[7][2] Power is provided by two General Electric T700-GE-401C turboshaft engines, each rated at 1,800 shp (1,342 kW); the vectored thrust ducted propeller system is driven by excess power from the main engines.[9][3] The X-49 retains armament provisions compatible with the SH-60 Seahawk, including options for torpedoes and missiles, although no such integration or testing was conducted on the experimental prototype.[7][2]| Specification | Value |
|---|---|
| Crew | 3 |
| Capacity | Up to 11 troops or equivalent cargo |
| Fuselage Length | 64 ft 10 in (19.76 m) |
| Height | 17 ft 4 in (5.28 m) |
| Rotor Diameter | 53 ft 8 in (16.36 m) |
| Wingspan | 36 ft (10.97 m) |
| Empty Weight | 13,650 lb (6,190 kg) |
| Max Takeoff Weight | 23,000 lb (10,433 kg) |
| Engines | 2 × General Electric T700-GE-401C (1,800 shp each) |
| Armament Provisions | SH-60 compatible (torpedoes, missiles; untested) |