SH-60J / SH-60K Anti-Submarine Helicopter
As the successor of the HSS-2B anti-submarine helicopter, the SH-60J is a licensed modification of the US Navy's SH-60B airframe. MHI is the primary contractor. It was developed under the unique concept of operation under Japan's policy to combat anti-submarine·anti-ship warfare by uniting the fleet with helicopters. Its first flight was in 1987, with a total of 70 units manufactured, including the test model, as of March 31, 2000, and a total of 103 units manufactured, including the test model, as of March 31, 2005.
The SH-60K, originally the "SH-60J Kai, is a new patrol helicopter developed as a successor to the SH-60J anti submarine helicopter. SH-60K is carried onboard a destroyer and in cooperation with the vessel fulfills versatile missions, such as anti submarine warfare, anti surface warfare, surveillance, transport, and rescue operations. For this purpose, Mitsubishi Heavy Industries (MHI) has put state-of-the-art technology to full use to develop the main rotor blade, avionics system, Ship Landing Assist System, and other systems of this specialized aircraft with the most advanced functions and levels of performance in the world. After the development phase from 1997 through 2002, technical and operational validation test were carried out by the Japanese government. The prototype aircraft initial flight was in JFY 13 (2001 year), and after which MHI delivered the first production aircraft to the Maritime Self-Defense Forces on 10 August 2005. MHI received production orders for a cumulative total of 21 aircraft during the period from 2002 to 2004.
As global conditions become ever more complex and needs of safety become greater than ever, Mitsubishi Heavy Industries, Ltd. (MHI) developed the new patrol helicopter SH-60K. Many improvements were made in the SH-60K over SH-60J. Characteristics of these are a new type of main rotor blade, avionics system, and Ship Landing Assist System (SLAS). The new type of main rotor blade is made of all-composite material, and has a unique shape with dihedral and anhedral angle at the blade tip, thereby improving hovering performance. The avionics system is integrally controlled by Advanced Helicopter Combat Direction System (AHCDS). With the adoption of an expert system, AHCDS can also provide the pilot with an optimum tactical plan. In addition, AHCDS has the function of exchanging tactical information among two or more escort helicopters. SLAS provides automatic guidance to and automatic landing on the base ship so as to reduce the pilot load, especially during nighttime operations when the field of vision is narrow. All of these improvements incorporate the world's most-advanced functions and performance.
Other improvements include the enlargement of the cabin (enlarged by 30 cm in length and 15 cm in height compared with SH-60J), as well as the installation of additional equipments such as a multifunction FDR (flight data recorder) and video transmission system.
SH-60K's main rotor blade has a unique blade tip shape with dihedral and anhedral angle and swept back angles which provides excellent aerodynamic characteristics during hovering flight. This design makes it possible to increase the maximum gross weight from 21 884 lbs for SH-60J to 24 000 lbs without increasing the rotor diameter over that of SH-60J, the base aircraft of the SH-60K. Composite materials are extensively used in the structure of the main rotor blade in order to realize this complex tip shape, as well as to achieve an optimum rigidity / weight distribution for a low vibration design, and to reduce weight and manufacturing costs. The wrap-around structure has been adopted for the blade attachments, in which a spar cap is wrapped around the lug hole to reduce the weight, facilitate the manufacturing process, and simplify blade installation and removal (blade installation by two sleeves). The spar cap is a member that mainly bears centrifugal force and bending loads. Aramid fiber reinforced plastic (AFRP) has been used for this member, which has superior strain fatigue strength.
The Ship Landing Assist System (SLAS) has the function of automatically carrying out operations of the approach of the aircraft to the base ship, automatic entry, and hovering and landing on the flight deck. Major aims of this system are to reduce the pilot workload and to improve a flight safety at nighttime and stormy wether. The function of SLAS is achieved by the dedicated system which is equipped on SH-60K and destroyer.
In automatic hovering phase, steady hovering not affected by ship motion is realized by controlling a aircraft for "fixed point in a space", which is obtained by subtracting the amount of ship motion measured with the SLAS Ship Motion Sensor (SSMS) from the relative position data. In addition, for disturbances such as turbulent flow due to a structure onboard the ship, hovering accuracy has been improved by using the actuator of the Stability Augmentation System (SAS) to control relative position and relative speed of the airframe. As a result, MHI succeeded in automatically landing a manned helicopter on a ship for the first time in the world.
Although it took nine years to complete the SH-60K production aircraft from the start of the development phase, the SH-60K will be used for a few decades to come. Therefore, MHI not only plans to improve the aircraft to make it even more reliable and easy-to-use, but also to put forward new proposals with an eye on global conditions, technological trends, and other factors.
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