Bell OH-58 Kiowa Light multi-purpose helicopter, has been in the service of the US Army since 1969 as a reconnaissance and direct fire support helicopter.
Despite numerous upgrades, everyone has long understood that the OH-58 has exhausted itself as a design. The possibilities of the AH-64 for modernization are also running out. Two spaces appeared in the US Army helicopters, two empty niches. The successful design of the S-97, coincidence, and simple luck will allow the new helicopter to fill two empty niches at once.
In 2008, an experimental Sikorsky X2 was built to test technical improvements, for flight testing of new products. During the flight tests, the designer encountered some serious problems. There was an acute problem with increasing flight speed. The fact is that when the screw rotates, the Retreating blade moving along the flight has a speed close to the speed of airflow. Thus, it works idle, that is, it does not create lift.
Sikorsky’s engineers, back in the early 1970s, found a way out of this situation. Two coaxial rotors have two independent swashplates. Automata regulate the drop in a lift by changing the angle of attack of the retreating blades. All lifting force is produced by leading blades. On the X 2 model, for the first time, a pushing turbojet engine (or a pair of them) was used, but a pushing propeller. This gave a sharp increase in speed (in the mid-70s, an unofficial world helicopter speed record of 487 km / h was set on S-69). In October 2008, they returned to the concept, and flight tests of the X 2 continued. The second serious problem of the helicopter blades was also solved. With increasing rotor speed, the movement of the tip of the blades approaches the speed of sound. Suddenly increases air resistance. The problem was solved thanks to the pushing screw.
At a certain point, the rotational speed of the bearing rotors slows down. The lifting force remains quite sufficient, the tips of the blades do not reach critical regimes, and the translational speed depends entirely on the pushing screw. So the speed of the new helicopter S-97 Raider went beyond the line of 400 km \ h. Although the engine and aerodynamics allow you to accelerate the car to speeds above 500 km \ h! The six-blade pushing propeller can change the pitch, which allows you to optimize and control the flight of the helicopter. The usual problem with helicopters is vibration, which was solved using an active vibration control system. The system includes measuring vibration frequency sensors and generators that extinguish by counteracting vibration a strictly defined frequency at various points on the fuselage. This allows you to make the flight comfortable for the crew and landing. The power unit on the new helicopter is still one and is borrowed from the UH-60M Black Hawk. The General Electric YT706 engine, with gearboxes and transmission, is driven by both main rotors and a thrust propeller. Soon, the Raider will receive its own engine, and its cruising speed will become even greater.
The crew of the machine consists of two pilots, the cargo-passenger compartment in the landing configuration holds 6 fully equipped infantrymen. The compartment can be transformed for a specific task. That is, it is universal. Transport, medical, assault – far from a complete list of modifications to the compartment. The helicopter has a fully electro-remote control system. There are no mechanical connections in management at all. This allowed to significantly reduce the weight of the helicopter and reduce its dimensions. The compactness of the helicopter is another advantage over competitors. The length of 11 m and the diameter of the rotor 10 m. allows reducing the size of the landing site by 15%, which is extremely important for rescue and combat operations. S-97 has a standard “body kit”, consisting of a diverse combination of 7, 62 or 12, 5 mm machine guns, a system for 7 Mk 4 FFAR missiles (2, 75 inches), or an AGM-114 Hellfire installation.
In 2015, it is planned to leave Apaches only in the army, removing them from the national reserve and the National Guard. So the S-97 hits two goals at once. Completely replaces OH-58 and partially AH-64.
The project of the Sikorsky S-97 helicopter is also unique in that it is completely built on private investment, a completely private company, without government funding.
S-97 is fully suitable for the US FVL Future Vertical Lift helicopter fleet replacement program, unlike its competitors Bell V-280 Valor and SB-1 Defiant (joint Sikorsky and Boeing), the first flights of which are planned only for 2017. Both helicopters should replace Apache, and in the niche of multi-purpose Raiders there are no equal, a competition was not even announced.
So: S-97 Raider is a high-speed, multi-functional, a new generation helicopter, so far, which has no competitors in the world. Terrible and dangerous warrior.
The program for developing a new type of helicopter model was launched in March 2010. There was a need to replace the Bell OH-58D Riowa Warrior helicopters with newer and more advanced models. Sikorsky has decided to develop a new helicopter with the launch of the first model in October 2014. Prototype prototypes began to be assembled in October 2012 in the amount of 2 units. When creating helicopters, the most advanced technologies are used, including the creation of the fuselage from composite materials.
Sikorsky and Boeing have developed a new design for the SB> 1 coaxial model (JMR TD) high-speed rigid rotor.
In the case of the adoption of a new helicopter model for the US Army, the UH-60 Black Hawk, and AH-64 Apache helicopter models will be replaced with total funding of $ 100 billion.
The first prototype was ready at the end of 2014 and will be used for intensive test flights, the second copy after being put into operation, is intended to participate in demonstration flights. Sikorsky invested $ 150 million in the creation of the helicopter, plus suppliers invested $ 200 million in the form of components and components for the helicopter. The estimated selling price of the helicopter will be $ 15 million.
The U.S. Department of Defense has not yet made a final decision to rearm with the transition to new helicopter models. In parallel with the military modification of the helicopter, a civilian version is being developed, which is planned to be produced for the delivery of personnel to oil production platforms.
The new Sikorsky S-97 Raider model has the characteristics of a power unit with a variable speed coaxial rotors and variable pitch. It is planned to produce models of helicopters controlled by 1 or 2 pilots, as well as with an automatic piloting system.
- The helicopter crew consists of 1-2 pilots or is controlled by an automatic piloting system.
- The passenger compartment is designed to carry 6 passengers.
- Dimensions of the helicopter: length 11 m.
- Maximum take-off weight – 4990 kg.
- The power plant consists of 1 General Electric YT706 engine with a capacity of 1900 kW.
- The diameter of the main rotor is 10 m.
- Main rotors – 6 blades with variable pitch and clutch cable pushing screw with a diameter of 2.1 m.
- Cruising speed – 407 km / h
- Flight range – 570 km
- Duration of flight – 2 hours 40 minutes
- The maximum ceiling is 3048 m.