Warplanes: July 19, 2004


The Marine Corps are likely to get a new exhaust for the AH-1 Super Cobra attack and UH-1 utility helicopters when these aircraft are remanufactured by Bell Helicopters to the AH-1Z and UH-1Y standard. Designed by Bell's XworX division, the new exhaust diverts hot gases out of the more powerful T-700 engines at about a 15 degree angle away from the tail boom, reducing the infrared signature by more than 50 percent over the current design by allowing the plumes to dissipate more quickly. Initially built to reduce the IR infrared, or heat) signature for protection against heat-seeking surface-to-air missiles, the new exhaust has the added benefit of reducing the stresses on the tail boom and engine compartment. With the existing design, the combined hotter thrust of the two T-700 engines was directed straight back at the tail boom, placing significant heat stress on the tail boom and leading to a shorter lifetime for all the parts it roasted. Bell is building exhaust system kits for retrofitting on AH-1W models in Iraq and Afghanistan first, with the entire fleet ultimately getting the modification. 

Initially, 100 UH-1N and 180 AH1W helicopters will be remanufactured into UH-1Y and AH-1Z models that share 80 percent common parts, including a glass cockpit. Bell is talking with the Marine Corps about building new model UH-1Y aircraft after the upgrade program ends due to the strains placed on the existing Corps helicopter fleet in world-wide deployments since 2001. The Marines may eventually do new builds of the AH-1Z for the same reason. Doug Mohney




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