Aircraft

USAF studies embedded engines for transport

By Graham Warwick

Inlet designs enabling fuel-efficient higher bypass-ratio turbofan engines to be buried in the airframes of future stealthy transport and surveillance aircraft are to be studied under a US Air Force Research Laboratory programme.

Current embedded engine installations, such as in the Northrop Grumman B-2 stealth bomber, use low-bypass turbofans and the greater airflow associated with a higher, more fuel-efficient bypass ratio poses design challenges for the serpentine inlet.

The AFRL plans to award multiple study contracts under its 19-month, $3.1 million Higher Bypass Ratio Inlet Development project. These will involve design trades for embedded engines having bypass ratios of 2:1 to 6:1 with windtunnel testing of a preferred inlet planned for 2009.

The focus is on inlets for a short take-off and landing transport with all-aspect survivability, able to operate from austere airfields yet cruise transonically. But contractors will be required to explore commonality with the inlet system for a persistent intelligence, surveillance and reconnaissance (ISR) platform.

The research laboratory says that no specific platforms have been identified, but the project appears to support the Advanced Joint Air Combat System, now in requirements definition at USAF Air Mobility Command as a potential future replacement for the Lockheed Martin C-130, as well as the laboratory's own SensorCraft ISR concept.