Haruko Ha-7 Akisame (Pacifica)

Ha-7 Akisame
Role	Attack helicopter
National origin	Pelinai
Manufacturer	Haruko Project Design Bureau
First flight	January 27, 1997 (1997-01-27)
Introduction	August 2006 (2006-08)
Status	In service
Primary user	Pelinese White Army
Produced	May 1, 1996 – present (1996-05-01 – present)
Number built	1,900+ (as of 2023)

The Haruko Ha-7 Akisame is a Pelinese twin-turboshaft conventional attack helicopter designed and manufactured by Haruko Project Design Bureau as a mobile, medium-range heavy ground strike platform for use by the Pelinese White Army.

Design

Vehicle systems

Armor system

The passive armor system of the Ha-7 consists of a combination of integrally armored fuselage panels, ballistic glass canopy panes, and additional reinforcing material around critical areas of the structure. Heavily protected areas such as the main rotor blades, the crew compartment, and the fuselage surrounding the main transmission gearbox are capable of resisting single impacts of up to 25mm cannon fire, while most of the remaining airframe is resistant to single impacts of up to 14.5x114mm tungsten-cored armor piercing rounds.

The main armor composition used throughout the airframe consists of fiber-reinforced epoxy composite panels, which form the majority of the airframe’s external paneling structure and act as an integral armor against impacts of 12.7mm and smaller rounds. The reinforcing fiber used is a woven fabric of high-performance magnesium oxide-rich aluminosilicate S-glass suitable for rigid armor applications. Armoring panels are made as monolithic as possible to minimize joints and seams while remaining consistent with system interface, maintenance access, and other considerations.

Critical areas of the structure receive additional armor protection to maximize survivability and reduce the likelihood of total system disabling by a lucky shot. These measures include both metal reinforcement, such as titanium flooring in the crew compartment, as well as composite-backed boron carbide ceramic armor tiles shielding areas such as the crew compartment and the main rotor gearbox assembly. Further special protective measures include a layered polycarbonate-acrylic transparent shield between the pilot and CPG compartments within the crew compartment, which significantly reduces the ability of single munition impacts to incapacitate both aircraft operators simultaneously.

Electrical systems

The electrical and power distribution system of the Akisame includes the two accessory drive-mounted AC generators on the main turboshaft engines, their associated generator control units, the auxiliary power unit (APU), the emergency ram air turbine, the main power distribution buses, the electricity storage batteries, miscellaneous electrical components such as the aircraft’s lighting systems, and the power distribution wiring.

Electricity generation on the Akisame is made to be highly redundant and survivable due to its heavy usage of electronic and electronic-mediated systems. Each input module connecting one of the two turboshaft engines to the main rotor gearbox is fitted with an AC alternator on its accessory drive to generate electric power for engine starters and other systems. Main power generation for avionics, mission equipment, control systems, and other core functions is performed by the Auxiliary Power Unit, which is itself fitted with a hydraulics-based starter. In the event of failure of all normal generator systems, the Akisame also carries a ram air turbine that may be deployed in order to provide modest electrical power for core flight-critical systems.

The Ha-7 carries a number of lighting systems for various utility functions, primarily during night operations. Both crew stations incorporate comprehensive green backlighting for visibility of non-display controls during night operations, while formation lights facilitate visibility to nearby friendly helicopters and formation flying in low-visibility conditions. Standard landing lights and navigation lights analogous to those on civilian helicopters are also mounted for utility purposes and usage outside of combat areas. All non-external lighting equipment may be turned on or off from the crew stations as necessary to minimize visibility.

Pilot support

The Ha-7 carries a variety of pilot support systems for aircrew comfort and protection. A crew compartment air conditioner & heater unit is installed to protect vehicle pilots from extreme temperatures during operations in hot or cold weather, while an overpressure CBRN defense system is also provided for operations in CBRN-contaminated environments. In the event of a downed aircraft, both crew members are supplied with survival kits containing food & water, medicine, basic survival supplies, and an AP-1999 personal defense weapon with ammunition.

Propulsion systems

The propulsion system of the Ha-7 includes most vehicle subsystems pertaining to the generation and usage of shaft power, such as its twin nacelle-mounted Yunimashi VD-94T turboshaft engines, as well as the main helicopter rotor assembly, the tail rotor assembly, the combined gearboxes & power transmission system, and the fuel storage & distribution system. Extensive computerization of control over parameters such as engine spool speed, fuel feed, and rotor RPM in the Akisame allows for benefits including reduced pilot workload and improved flight efficiency while simultaneously removing complex and maintenance-intensive hydromechanical valves and other equipment.

Engines

The main engines of the Ha-7 consist of two Yunimashi VD-94T turboshaft helicopter engines mounted in pods on the upper sides of the central fuselage. The currently used VD-94T2 model of the Ha-7V is rated for a maximum continuous shaft power of 1,254kW at roughly 20,000 RPM, for a total main rotor power of 2,508kW. 30-minute power of each engine amounts to 1,429kW for takeoff, while 3-minute contingency power for emergency situations such as a one-engine inoperative condition is 2,001kW. The high power settings on the engines allows the Akisame to maintain controlled flight even with an engine disabled by mechanical failure or combat damage, substantially improving system reliability and combat survivability. Both engines are fitted with triple-redundant full-authority digital engine control (FADEC) systems that monitor engine conditions and adjust output parameters such as gas generator spool RPM and free spool RPM to obtain flight states commanded by the vehicle operators.

Fuel system

The fuel system of the Akisame includes its fuel tanks, fuel distribution hoses, fuel pumps, and miscellaneous equipment such as filters, as well as the fuel control units fitted to the main turboshaft engines. It is designed to be extensively redundant, damage tolerant, and crashworthy, with numerous features intended to prevent fuel leakage through severed connections.

The Akisame utilizes four separate self-sealing fuel tanks; each turboshaft engine is nominally designated to receive fuel from two of the four tanks, though fuel can be transported between each side using a transfer pump; the helicopter’s APU is also connected to both sides. Fuel is distributed in self-sealing fuel hoses wrapped in stainless steel braiding. In order to prevent battle or crash damage from creating fuel leaks and fire hazards, the fuel distribution system is interspersed with one-way valves, frangible connectors, and other fixtures that automatically seal damaged connections and stop leakage of fuel.

In order to prevent ice obstruction of fuel filters and other system components, the fuel system of the Ha-7 is equipped with fuel-oil heat exchangers that utilize heat from the transmission to eliminate small ice particles. In the event that ice does accumulate in the filters as detected by a large pressure drop across them, a diagnostic alert will be issued to the crew interface.

Rotor assemblies

The main rotor assembly of the Ha-7 consists of a five-bladed, fully articulated rotor head that receives power directly from the main shaft of the main gearbox assembly inside the fuselage. The helicopter rotor blades themselves are manufactured from fiberglass and carbon fiber-reinforced polymer with a composite main structural spar, while their geometry consists of a high-solidity wide-chord design with blade tip sweep, taper, and anhedral. Blades are attached to the main rotor hub, which also mounts a search and fire control radar system, using a combination of elastomeric and conventional bearings. Rotor parameters such as blade pitch angle and swashplate position are indirectly controlled through control inputs by the pilot, which are converted into movements of the appropriate hydraulic actuators by the fly-by-wire system.

The tail rotor assembly is constructed similarly to the main rotor assembly, though with some features such as the swashplate removed. It is mounted high on the helicopter’s rudder with a powered shaft connecting to the tail rotor gearbox and an added blade pitch control assembly. The tail rotor blades also lack the blade tip features present on the main rotor.

Transmission

The Akisame uses a conventional main gearbox assembly with a lightweight welded, corrosion-resistant stainless steel case and carburized medium alloy steel gears; it is connected to the main engines through two shaft power input modules, which mount the engines’ accessory drives and associated components such as generators and hydraulic system pumps. Both the input modules and the main transmission incorporate sprag clutches in their design as a safety feature, both in order to prevent an inoperative engine from impeding transmission rotation by the other and in order to prevent a wholly inoperative engine and/or transmission assembly from impeding autorotation of the main rotor.

The tail rotor receives power from the main gearbox though a power take-off, which feeds into a tail rotor drive shaft, an intermediate gearbox at the base of the rudder, and a tail gearbox that rotates the shaft outward and connects to the tail rotor assembly itself.

Avionics systems

The Akisame possesses a wide variety of advanced communications, situational awareness, sensor, and other avionics systems not utilized on previous Pelinese rotorcraft. Its core functionality include wide-spectrum radio communication with both nearby units and satellites, station-, satellite-, and INS-based navigation, improved IFF and friendly force tracking capabilities, and an extensively overhauled pilot interface system incorporating multifunction displays, helmet-mounted displays, and other equipment. In order to speed maintenance operations, simplify equipment upgrades, and maximize system availability, avionics systems on the Akisame that cannot be repaired in the field are almost exclusively confined to line-replaceable units that can be removed and replaced quickly.

Diagnostics

The diagnostics system of the Ha-7 includes all equipment used to detect and, where possible, correct mechanical, electronic, and other system faults; this includes the onboard health and usage monitoring system (HUMS), oil system chip detectors, equipment condition monitoring sensors, and other such devices. The Akisame’s central flight control computer is additionally capable of using the diagnostics system to identify flight events such as damaged fuel/oil lines or a one engine inoperable (OEI) condition and implementing corrective measures.

The health and usage monitoring system utilized by the Ha-7 uses measured vibration, temperature, shaft RPM, time since component installation, and other flight system data to monitor the condition of key components such as the transmission components, the rotor blades, and the engines in order to detect the imminent need for overhaul or replacement of subsystems. Though it is primarily used by maintenance personnel to record relevant data and perform appropriate preventative maintenance, the data and parameters that it records may also be checked in-flight.

Armament system

Autocannon

The autocannon subsystem on the Akisame includes the FHE N30L 30x113mmB autocannon, its traversal equipment, and the ammunition storage & feed system; all of these are mounted on the forward ventral side of the helicopter under the crew compartment. The autocannon is intended for ground support fire roles against both dismounted infantry and armored vehicles, with a maximum elevation of 12° and a maximum depression of 58°. Control of the autocannon system is normally assigned to the copilot/gunner station, but may be transferred to the pilot station as with other system controls; the current gun operator may also link the turret’s traverse to their flight helmet and aim it through movement of the head.

The ammunition storage & feed assembly holds a maximum of 1,000 30x113mmB autocannon rounds for the ventral autocannon. Ammunition types normally loaded onto the Akisame include high explosive, armor piercing incendiary, and armor piercing incendiary tracer; other 30x113mmB ammunition types can, however, be loaded as long as they are compatible with the N30L.

See also

• Aircraft of comparable role, configuration, and era: