Bell Helicopter H1

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.

The AH-1Z and UH-1Y share a common tail boom, engines, rotor system, drive train, avionics architecture, software, controls and displays for over 84% identical components.[28][29] 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.[27] 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.