The US Army has assigned the "Fox" designation to OH-58D Kiowa Warriors receiving a series of future cockpit and sensor upgrades, but stopped short of committing to a proposed engine improvement.
The OH-58F, or "Fox", fleet is expected to be fielded in the fourth quarter of 2015.
Although once programmed for retirement, the army has invested heavily in cockpit and sensor upgrades for the OH-58D with funds loosened from the cancellation in 2007 of the Bell ARH-70 Arapaho armed scout helicopter.
Even with the Fox-model upgrades, the Vietnam-era design of the Kiowa fleet will still lack the ability to meet a key requirement identified by the army for operations in mountainous Afghanistan.
The improved Kiowa requires a major engine upgrade to achieve hover out of ground effect at 6,000ft on a 35ºC (95ºF) day.
Rolls-Royce is proposing to boost the power of the current Model 250-CR30 engine by 12% to achieve the "high-hot" requirement.
Bell Helicopter, meanwhile, is internally investing in a technology demonstrator that re-engines the Kiowa Warrior with the Honeywell HTS900-2, the engine originally selected to power the Arapaho. Although adding about 100lb to the Kiowa's takeoff weight, the HTS900-2 delivers 50% more power.
The army, however, has approved funding to integrate a digitally-based glass cockpit. The army also is proposing to replace the mast mounted sensor with a nose mounted targeting and surveillance system.
The upgrades are intended to provide a bridge that keeps the Kiowa Warrior viable until the army can decide how to replace it.