page_title: H-1 upgrade program
section_title: Common Elements
hierarchical_section_title: H-1 upgrade program / Upgrades / Common Elements
caption_attribution_description: English: AH-1Z "Viper SuperCobra" pilots 1st Lt. Michael "Shitshow" Tetreault and Capt. Travis Patterson aboard USS Makin Island prepare to fly Oct. 5. The pilots (originally from Marine Light Attack Helicopter Squadron 367, AKA "Scarface") serve with the 11th Marine Expeditionary Unit's (MEU) Aviation Combat Element (ACE). The 11th Marine Expeditionary Unit is the first amphibious landing force to embark Makin Island, which set sail for San Francisco Oct. 1 to participate in the city's 2010 Fleet Week. There the 11th MEU plans to showcase to the public the Marine Corps' men and women, its aircraft and equipment, and its ability to conduct missions that span the overlapping spectrums of peace and combat, from disaster relief to war. Tetrealt is from Killingly, Conn., and Patterson is from Austin, Texas. (Official U.S. Marine Corps photo by Cpl. Preston Reed)
context_page_description: The H-1 upgrade program is the United States Marine Corps's program to develop the AH-1Z Viper and UH-1Y Venom military helicopters to replace its aging fleets of AH-1W SuperCobras and UH-1N Twin Hueys. The contract was awarded in 1996 to Bell Helicopter, the original manufacturer of both aircraft, to design the new airframes as modernized attack and utility helicopters with considerable design commonality, to reduce operating costs.
context_section_description: The AH-1Z and UH-1Y share a common tailboom, engines, rotor system, drivetrain, avionics architecture, software, controls and displays for over 84% identical components. Both aircraft use twin General Electric T700-GE-401C turboshaft outputting 1,800 shp (1,350 kW) each. Upgrades will also be made to the transmission (rated for 2,350 hp (1,750 kW)) and skid landing gear.
  The existing two-bladed semi-rigid, teetering rotor system is being replaced with a four-bladed, hingeless, bearingless composite rotor system. The improvement in flight characteristics provided by the four-bladed configuration has led to increases in flight envelope, maximum speed, vertical rate-of-climb, payload and  reduced rotor vibration. The rotor system has 75% fewer parts than that of four-bladed articulated systems, and the improved yokes allow for weight saving with the elimination of all bearings, hinges, and vibration absorbers in the rotor hub. The blades are made of carbon fiber-based composites, which have an increased ballistic survivability, and there is a semiautomatic folding system for stowage aboard Amphibious assault ships. Both helicopters will receive an upgraded, four-blade tail rotor and drive system.
  The new integrated avionics system (IAS) has been developed by Northrop Grumman. The system includes two mission computers, an automatic flight control system (reportedly "stops short of a fly-by-wire system"), and a glass cockpit; Bell suggests the system can withstand 23 mm caliber fire. Each crew station has two 8 by 6 in (20 by 15 cm) multifunction liquid crystal displays (LCD) and one 4.2 by 4.2 in (11 by 11 cm) dual function LCD display. The communications suite combines a US Navy RT-1824 integrated radio, UHF/VHF, COMSEC, and modem in a single unit. The navigation suite includes an embedded GPS inertial navigation system (EGI), a digital map system and a low-airspeed air data subsystem, which allows weapons delivery when hovering. The new cockpit systems will increase joint interoperability, now able to transmit and receive data from ground and air systems from other branches.
  The Lockheed Martin Target Sight System (TSS) incorporates a third-generation FLIR sensor. The TSS provides target sighting in day, night or adverse weather conditions. The system has various view modes and can track with FLIR or by TV. It is also used on the KC-130J Harvest HAWK.
  The pilot and copilot are equipped with the Thales "Top Owl" helmet-mounted sight and display system. The Top Owl has a 24-hour day/night capability and a binocular display with a 40° field of view.  Its visor projection provides forward looking infrared (FLIR) or video imagery. However, the Corps has decided to augment it with existing night vision devices.
caption: AH-1Z pilots aboard the USS Makin Island wear helmet-mounted displays
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