Low Observable Asymmetric Nozzle
During late-1996, A USAF F-16C and its F100-PW-200 engine were modified by a Lockheed Martin/Pratt & Whitney team. A LOAN (Low-Observable Asymmetric Nozzle) nozzle from the JSF (Joint Strike Fighter) Program Office was fitted on the engine for ground testing in a two-day rapid prototype operation. Developed under the Joint Strike Fighter 'BAA 94-2' program to evaluate advanced, affordable technologies applicable to the JSF, the LOAN provides a significant reduction in radar cross section and infrared signature emissions from the engine, as well as the potential for reduced maintenance costs.
During tests from idle to maximum afterburner, measurements were taken of infrared images, nozzle temperatures, and nacelle inlet pressures and airflow velocities. The nozzle also has been successfully tested on the Pratt & Whitney JTDE FX650 (Joint Technology Demonstrator Engine) for the JSF program.
With the LOAN, stealth is achieved through a combination of technologies. These include geometrical shaping, an advanced cooling system, and special coatings on internal and external structures. Due to the effectiveness of the advanced cooling system, the life of the nozzle divergent flaps will be more than doubled, resulting in significant maintenance cost savings.
LOAN is applicable to both retrofit and new production aircraft. Applications of the nozzle could involve the next-generation Joint Strike Fighter, as well as the world fleet of F-16 aircraft. According to Carl McMurry, program manager of Lockheed Martin's F-16 Ejector Nozzle Integration program, "The LOAN exhaust system incorporates technologies that will make JSF more survivable and affordable, but are available now and can significantly improve fielded weapon systems such as the F-16."
Ground testing at Lockheed Martin Tactical Aircraft Systems, of the Low Observable Axisymmetric Nozzle (LOAN) was completed in November 1996. The next step in the LOAN program is a flight demonstration, which is currently in the planning stages.