INTERNATIONAL AERO Engines (IAE) and Calcor Aero Systems are to develop the world's first variable-area exhaust nozzle for a civil aero-engine.

IAE, a joint venture between Pratt & Whitney, Rolls-Royce, MTU, FiatAvio and Japanese Aero Engines, will work with California-based Calcor to produce a technology demonstrator for IAE's V2500 turbofan, which powers some Airbus A320s and the McDonnell Douglas MD-90. Variable nozzles have been widely used on military engines, but the concept has never been applied to a big commercial turbofan.

The variable nozzle will vary the exhaust-exit area by about 15% and could yield a 4% increase in take-off thrust, as well as improvements in climb and cruise performance. Nozzle movement would be controlled by the engine's full-authority digital engine-control system, allowing the exhaust area to be optimised for specific operating conditions.

IAE says that Calcor variable-area nozzle technology is "simple, lightweight and durable", making it suitable for commercial applications. The mechanical complexity of the design will cause a small weight penalty and higher maintenance costs, however.

The new nozzle is scheduled to enter the test phase at the end of 1996, when a prototype Calcor nozzle will be fitted to a V2500-A5.

Source: Flight International