Most writers state that Sorikin failed to build a working (or complete) machine in St. Petersburg, mainly because of a low power engine. On the eve of WW1 Sorokin completed his (modified) helicopter design in his home place at Novgorod-Seversky (Ukraine) [Новгород–Северски] after a long development during 1911-1914. It is stated that the machine was tested and actually flew. The construction was based on the two rotors and a tractor propeller. There were rudders to steer the machine.
Preduzece SOKO
SOKO Vazduhoplovna Industrija, Ro Vazduhoplovstvo
Soko Air Ltd
Bosnia-Herzegovina
Founded as Preduzece SOKO in October 1950, and produced license-built Westland Whirlwind helicopters. Designed the G-2A Galeb two-seat armed jet basic trainer (first flown 1961), produced for the Yugoslav Air Force and for export. Designed the J-1/RJ-1 Jastreb attack and reconnaissance versions of Galeb, and the P-2 Kraguj piston-engined counterinsurgency aircraft (first flown 1966); the G-4 Super Galeb jet trainer (first flown July 1978). Built the Aerospatiale/Westland Gazelle helicopter under license in several versions, including Partizan, GAMA antiarmor model and HERA reconnaissance model; and joined lAv Craiova of Romania in development/ production of J-22 Orao/IAR-93 attack aircraft (first flown 1974 but out of production before all deliveries made, due to regional conflict).
Privatized 1991, at which time extensive subcontract work included components/ assemblies for Airbus, ATR, Dassault, de Havilland, EMBRAER, Eurocopter, McDonnell Douglas and Tupolev commercial aircraft. Did not go out of business during regional conflict that followed, but had short periods of inactivity during the worst of the troubles.
Following 1998 restructure of Soko company and its division into several smaller concerns under Soko Holding Co, Soko Air Ltd. was created at the Mostar-Rodoc factory to undertake its aviation programs. They include the Soko 2 two-seat very light monoplane (first flown November 1996) and LH1 two/three-seat light helicopter, which was at an advanced stage of design at time of writing. Other work includes civil aircraft component production for international customers, and design of four- and six-seat lightplanes.
The first post-War Dutch-built helicopter the Sobeh-l, was developed into the Sobeh H-2. Its all-metal, all-bonded rotor had automatic stability and transfers automatically into auto-rotative pitch in case of engine failure. The rotor was turned initially by a separate 1 hp bicycle engine.
Sobeh H.2
Power: 2 x 50 h.p. ramjet
Rotor diameter: 30 ft
Rotors: 2- blade tip-powered
Loaded weight: 1,350 lb
Max. speed: 70 mph
Seats: 2
The first post-War Dutch-built helicopter the Sobeh-l, flew in 1954. The design was developed into the Sobeh H-2.
Designed by Ing. J. Slechty in Czechoslovakia, this helicopter was tested in 1951, powered by a Praga engine.
Engine: Praga piston
Rotors: 2-blade main 2-blade tail
Seats: 1
1985:
Skyhawk Helicopters,
Liberal KS.
Reportedly produced 1 aircraft and 2 kits.
1988: Ended operations.
First flown in April 1977 was a single example of the Silvercraft SpA SH-200 two-seater.
A replacement for the SH-4.
Italy
Formed early 1962. In October 1963 flew XY prototype light helicopter, further developed with financial and technical assistance of shareholder SIAI-Marchetti. SH-4 (flown 1963 in XY prototype form and 1965 as SH-4) was first helicopter of all-Italian design and construction to receive both Italian and U.S. certification. By late 1960s serious production had begun as SIAI-Marchetti/Silvercraft SH-4, but under name Silvercraft alone deliveries began 1970. Production ceased 1977, as single example of SH-200 two-seater first appeared.
Sikorsky and development partner Boeing inched closer to the first flight of the SB-1 “Defiant” compound helicopter prototype this week, receiving FAA registration number N100FV and officially designating it the “S-100,” serial number MSN 0001. The SB-1 is Sikorsky’s entry into the Pentagon’s Future Vertical Lift (FVL) competition, a program that ultimately could result in deliveries of as many as 4,000 aircraft by 2030 under a contract potentially worth $100 billion and including significant foreign military sales.
First flight was anticipated by the end of this summer, but it appears that will now slip somewhat as it took Sikorsky longer than anticipated to work through a variety of technical issues, including main rotor blades and fashioning solutions to complex transmission issues related to power distribution between the main rotors and the thruster.
The SB-1 uses the same technology Sikorsky developed for its X2 and S-97 demonstration aircraft. A second S-97 recently resumed test flying after the first aircraft was substantially damaged during a hard landing a year ago at Sikorsky’s West Palm Beach, Florida test facility.
The SB-1 is slated to compete against Bell’s V-280 third-generation tiltrotor. It features an all-composite fuselage with seating for 12 fully kitted troops and a crew of four, a rigid coaxial main rotor system, an aft thruster with a clutch, and full fly-by-wire flight controls.
The SB-1 will initially be powered by a pair of Honeywell T-55 engines but will later be upgraded to the winner of the Future Affordable Turbine Engine (FATE) competition. The aircraft is expected to have a cruising speed of 250 knots.
The Sikorsky S-97 Raider is a high-speed scout and attack compound helicopter based on the Advancing Blade Concept (ABC) with a coaxial rotor system. Sikorsky planned to offer it for the United States Army’s Armed Aerial Scout program, along with other possible uses.
First proposed in response to a Request for Information for the Armed Aerial Scout (AAS) program in March 2010, the S-97 was formally launched on 20 October 2010. It was intended as a contender for a United States Army’s requirement to replace the Bell OH-58D Kiowa Warrior. Other military roles are possible, the U.S. Special Operations Command having expressed interest in the S-97 as a replacement for the MH-6 Little Bird, and the possibility of adapting it for civilian applications also exists.
Sikorsky plans to build two prototypes of the S-97 as demonstrators. One prototype (P1) will be used for flight testing, while the second (P2) is planned for use as a demonstrator.
Sikorsky started construction of the two prototypes in October 2012. In September 2013, Sikorsky began final assembly of the first S-97 following delivery of the single-piece, all-composite fuselage by Aurora Flight Sciences. In February 2014, construction of the first S-97 prototype was one-quarter complete. Simulated bird strikes testing had been conducted on the fuselage at speeds of up to 235 kn (435 km/h; 270 mph), the S-97’s expected maximum flight speed. Drop tests were also performed to ensure the fuel tanks’ safety in the event of a crash.
Sikorsky targeted the S-97 for the AAS program, aiming for the helicopter to fly before the Army down-selected. Sikorsky invested $150 million and its 54 suppliers (who provide 90% of the parts) spent the remainder of a total of $200 million on two prototypes; production models aim to meet the program’s $15 million unit cost target. However, the Army ended the AAS program in late 2013. Budget projections for FY 2015 included retiring the U.S. Army’s OH-58 Kiowa fleet and transferring AH-64 Apache attack helicopters from U.S. Army Reserve and U.S. Army National Guard to the active Army to perform the aerial scout role. Sikorsky suggested the possibility of buying the S-97 to replace lost Apache for armed helicopter needs. Sikorsky proposes S-97 as FVL-CS1; the light scout helicopter.
The S-97 design includes variable speed rigid coaxial main rotors and a variable-pitch pusher propeller, making the S-97 a compound helicopter. Like the X2, it has fly-by-wire control and dynamic anti-vibration actuators to cancel out shaking. The main rotors have hingeless hubs and stiff blades, to improve low-speed handling and efficiency of hover. At high speeds, the close spacing of the hubs reduces drag. The stiff blades allow each rotor to have low lift on the retreating side of its rotor disk (reducing drag), whereas each rotor on a conventional coaxial rotor with “floppy” blades needs nearly equal lift distribution. The propeller relieves the rotor of propulsion, further reducing drag.
Maneuverability is improved compared with earlier helicopters because of the ability to tilt the coaxial rotors together or tilt each one differently, and because of the variable pitch propulsor and active elevons. At low speed the S-97 yaws by differential torque of the upper and lower rotor, at high speed it uses rudders.
The S-97 is capable of carrying up to six passengers, in addition to a flight crew of two in a side-by-side cockpit. However, the production S-97 is projected to be capable of flying with either one or two pilots, or autonomously. Space for a targeting sensor has been reserved, however not installed in the prototype aircraft.
Based on the technology from the Sikorsky X2 demonstrator, the prototype S-97s is powered by a General Electric YT706 turboshaft (the same engine used on the MH-60M Black Hawk). Compared to the OH-58D Kiowa, the S-97 has significantly increased performance goals, such as cruising speeds upwards of 200 knots while carrying weapons, turning at three times the force of gravity at 220kt, and a high hover efficiency (Figure of merit). Sikorsky also aims for an operating cost of $1,400 per flight hour.
Its avionics were powered on in June 2014, with rollout on 2 October 2014. The first flight of the S-97 occurred on 22 May 2015. It flew for 1 hour instead of the planned 30 minutes, completing three takeoffs and landings; forward, rearward and sideward. For this initial flight, the Raider was flown with its triplex fly-by-wire flight control system in backup degraded mode so as to focus on basic airworthiness in the low-speed regime. This begins a year-long flight test program of about 100 flight-hours to expand the flight envelope to meet Sikorsky’s key targets of 220-knot cruise speed carrying weapons, hover at 6,000 feet on a 95F day and 3g maneuverability at speed. Toward the end of Phase 1 testing, software will be upgraded to Block 2, bringing in the propulsor and articulating tail to increase speed and enable the full flight envelope. The second prototype (P2) was displayed to the public in October 2015. After two flight hours and a few months of testbench validation of the propulsion drivetrain, P1 is scheduled for higher speed some time in 2016.
On 3 August 2017, an S-97 prototype suffered what Sikorsky described as a hard landing at their flight test facility in West Palm Beach, Florida; both airline transport pilots received minor injuries. The NTSB factual report on the incident stated that the helicopter lifted into a low hover and immediately experienced excessive roll oscillations which lead to intermeshing of the counter-rotating coaxial rotor system, and a hard landing. Damage to the helicopter included collapsed landing gear, structural cabin damage, and dynamic component damage, including rotor blade tip separation of all rotor blades. Video of the accident sequence showed aircraft roll oscillations exceeding 60–degree angle of bank during the course of 5 seconds, during which the upper and lower rotors collided at the 1 o’clock position.
On 25 June 2019, the S-97 returned to flight testing and reached a speed of 190 knots.
Sikorsky and partner Boeing are to use the S-97’s technology and design process as a basis to develop the SB-1 Defiant, a high-speed rigid rotor co-axial rotorcraft, for the army’s Joint Multi-Role Technology Demonstrator (JMR TD) program.
Powerplant: 1 × General Electric YT706, 2,600 shp (1,900 kW)
Main rotor diameter: 1 (2 coaxial) × 34 ft (10 m)
Propeller: 1 x 6-bladed variable-pitch, clutchable pusher propeller (7 ft (2.1 m) diameter)
Length: 35 ft (11 m)
Gross weight: 8,945 lb (4,057 kg)
Max takeoff weight: 11,000 lb (4,990 kg)
Cruise speed: 250 mph (410 km/h, 220 kn) (with external weapons)
Never exceed speed: 280 mph (440 km/h, 240 kn)
Range: 350 mi (570 km, 310 nmi)
Endurance: 2 h 40 min
Service ceiling: 10,000 ft (3,000 m) at 95 °F (35 °C)
Crew: 0–2 pilots
Capacity: 6 troops
Armament: .50 cal gun with 500 rounds
All Aero 