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Bell_OH-58_Kiowa
OH-58A Kiowa là một trực thăng quan sát 4 chỗ ngồi. The Kiowa has two-place pilot seating, although the controls in the left seat are designed to be removed to carry a passenger up front. During its Vietnam development, it was fitted with the M134 Minigun, a 7.62 mm electrically operated machine gun.
The Australian Army leased 8 OH-58A helicopters in 1971 in Vietnam for eight months.[66][67]
A total of 74 OH-58A helicopters were delivered to the Canadian Armed Forces as COH-58A and later redesignated CH-136 Kiowa.[68] As many as 12 surplus Kiowas were sold to the Dominican Republic Air Force, and others sold privately in Australia.[69]
In 1978, OH-58A aircraft began to be converted to the same engine and dynamic components as the OH-58C.[70] And, in 1992, 76 OH-58A were modified with another engine upgrade, a thermal imaging system, a communications package for law enforcement, enhanced navigational equipment and high skid gear as part of the Army National Guard's (ARNG) Counter-Drug RAID program.
The U.S. Army retired its last OH-58A in November 2017.[71]
The OH-58B was an export version for the Austrian Air Force.[72] The Australian Government also procured the OH-58A for the Australian Army and Royal Australian Navy as the CAC CA-32.[67][73] Produced under contract in Australia by Commonwealth Aircraft Corporation, the CA-32 was the equivalent of the 206B-1 (upgraded engine and longer rotor blades). The first twelve of 56 were built in the U.S. then partially disassembled and shipped to Australia where they were reassembled.[66] Helicopters in the naval fleet were retired in 2000.[66]
Equipped with a more robust engine, the OH-58C was supposed to solve many issues and concerns regarding the Kiowa's power. In addition to the upgraded engine, the OH-58C had unique IR suppression systems mounted on its turbine exhaust. Early "C" models featured flat-panel windscreens as an attempt to reduce glint from the sun, which could give away the aircraft's location to an enemy. The windscreens had a negative effect of limiting the forward view of the crew, a previous strength of the original design.
The aircraft was also equipped with a larger instrument panel, roughly a third bigger than the OH-58A panel, which held larger flight instruments. The panel was also equipped with Night Vision Goggle (NVG) compatible cockpit lighting. The lights inside the aircraft are modified to prevent them from interfering with the aircrews' use of NVGs.[74] OH-58C aircraft were also the first U.S. Army scout helicopter to be equipped with the AN/APR-39 radar detector, a system which allowed the crew to know when there were anti-aircraft radar systems in proximity to the aircraft.[75]
Some OH-58C aircraft were armed with two AIM-92 Stingers. These aircraft are sometimes referred to as OH-58C/S, the "S" referring to the Stinger installation.[76] Called Air-To-Air Stinger (ATAS), the weapon system was intended to provide an air defense capability.
As of November 2017, the OH-58C is the only variant of the Kiowa in active service of the US Army, used as a training aircraft.[71] On ngày 9 tháng 7 năm 2020, the US Army retired the last OH-58Cs from service.[3]
The OH-58D (Bell Model 406) was the result of the Army Helicopter Improvement Program (AHIP). An upgraded transmission and engine gave the aircraft the power it needed for nap-of-the-earth flight profiles, and a four-bladed main rotor made it much quieter than the two-bladed OH-58C. The OH-58D introduced the distinctive Mast-Mounted Sight (MMS) above the rotor system, and a mixed glass cockpit, with traditional instruments identified as "standby" for emergency use.
The Bell 406CS "Combat Scout" was based on the OH-58D (sometimes referred to as the MH-58D). Fifteen aircraft[8][77] were sold to Saudi Arabia.[78] A roof-mounted Saab HeliTOW sight system was opted for in place of the MMS.[79] The 406CS also had detachable weapon hardpoints on each side.
The AH-58D was an OH-58D version operated by Task Force 118 (4th Squadron, 17th Cavalry) and modified with armament in support of Operation Prime Chance. The weapons and fire control systems would become the basis for the Kiowa Warrior. AH-58D is not an official DOD aircraft designation, but is used by the Army in reference to these aircraft.[80][81][82]
The Kiowa Warrior, sometimes referred to by its acronym KW, is the armed version of the OH-58D Kiowa. The main difference that distinguishes the Kiowa Warrior from the original AHIP aircraft is a universal weapons pylon found mounted on both sides of the aircraft. These pylons are capable of carrying combinations of AGM-114 Hellfire missiles, air-to-air Stinger (ATAS) missiles, 7-shot 2,75 inch (70 mm)[Chuyển đổi: Số không hợp lệ] Hydra-70 rocket pods,[83] and an M296.50 caliber machine gun. The standard of performance for aerial gunnery from an OH-58D is to achieve at least one hit out of 70 shots fired at a wheeled vehicle 800 đến 1.200 m (2.600 đến 3.900 ft) away.[84][85] The Kiowa Warrior upgrade also includes improvements in available power, navigation, communication and survivability, as well as modifications to improve the aircraft's deployability.[86]
The OH-58F is the designation for an upgrade of the OH-58D. The Cockpit and Sensor Upgrade Program (CASUP) features a nose-mounted targeting and surveillance system in addition to the OH-58D's mast-mounted sensor. The AAS-53 Common Sensor Payload (CSP) includes an advanced infrared camera, color Electro-Optical camera, and image intensifier; it is expected to improve flight performance by 1–2% through weight and drag reductions.[87] Cockpit upgrades include the Control and Display Subsystem version 5, for more processing and storage power, three color multi-function displays, and dual-independent advanced moving maps. The OH-58F shall have Level 2 Manned-Unmanned (L2MUM) teaming, the Force Battle Command Brigade and Below (FBCB2) display screen, with future improvement to Blue Force Tracker 2. Survivability enhancements include ballistic floor armor and the Common Missile Warning System (CMWS). Other features include improved situational awareness, digital inter-cockpit communications, HELLFIRE future upgrades, redesigned wiring harness, Health and Usage Monitoring (HUMS), and enhanced weapons functionality via 1760 digital interface. It has a dual-channel, full-authority digital engine-controller to ensure operations at required power levels in all environments.[88][89][90] To address power requirements, Rolls-Royce proposed adaptions to its 250-CR30 engine to increase output by 12%.[91] The OH-58F is powered by a Rolls-Royce 250-C30R3 engine rated at 650 shp (480 kW).[92]
In October 2012, the first OH-58F was finished. Unlike most military projects, the Army designed and built the new variant itself, which lowered developmental costs. It weighed 3.590 lb (1.630 kg), 53 lb (24 kg) below the target weight and about 200 lb (91 kg) lighter than the OH-58D. The weight savings are attributed to more efficient wiring and a lighter sensor. The first production aircraft started being built in January 2013 and was handed over to the Army by the end of the year. Low rate production was to start in March 2015, with the first operational squadron being fully equipped by 2016. The Army was to buy 368 OH-58Fs, with older A, C and D-model OH-58s to be remanufactured into F-models.[93] Because of battle damage and combat attrition, total OH-58F numbers would be about 321 aircraft.[94] The first flight of the OH-58F occurred on ngày 26 tháng 4 năm 2013.[95]
The Army chose to retire its Kiowa fleet and end the F-model CASUP upgrades. CASUP and SLEP upgrades would cost $3 billion and $7 billion respectively, totaling $10 billion for features that the Army cannot afford to allocate money to. The OH-58D can reach 20 percent of armed aerial scout mission requirements, upgrading to OH-58F standard would raise that to 50 percent. Replacing the Kiowa with Apaches and unmanned systems in scout roles would meet 80 percent of requirements.[96] In the first quarter of 2014, Bell received a stop-work order for the Kiowa F-model CASUP program.[97]
On ngày 14 tháng 4 năm 2011, Bell performed the successful first flight of their OH-58F Block II variant. The Block II was Bell's entry in the Armed Aerial Scout program.[98] It built on the improvements of the F-model, and added features including the Honeywell HTS900 turboshaft engine, the transmission and main rotors of the Bell 407, and the tail and tail rotor of the Bell 427. Bell started voluntary flight demonstrations in October 2012, and the Army had to decide by December if it would even proceed with the AAS program.[99] Bell hoped for the Army to go with their service life extension models instead of the program. The F-model Kiowa is an "obsolescence upgrade", while the Block II was seen as the performance upgrade. This gave the Army flexibility in times of shrinking budgets, as they had the option of upgrading the Kiowa to the F-model and then continuing to the Block II later when there were sufficient funds.[100] Shortly before December 2012, the Army decided they would recommend proceeding with the AAS program.[47][48] The Army ended the AAS program in late 2013.[101] With the onset of sequestration budget cuts in early 2013, it was decided that the $16 billion cost of buying new armed scout helicopters was too expensive.[96]
The OH-58X was a modification of the fourth development OH-58D (s/n 69-16322) with partial stealth features and a chin-mounted McDonnell-Douglas Electronics Systems turret as a night piloting system; including a Kodak FLIR system with a 30-degree field of view. Avionics systems were consolidated and moved to the nose, making room for a passenger seat in the rear. No aircraft were produced.[2]
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