Modeling the Infrared Intensity of a Large Commerical Aircraft Thesis

Measuring the infrared signature of large civilian aircraft has become increasingly important due to the proliferation of man-portable air defense systems (MANPADS) and the increasing threat of their use by terrorists. Because of the range of these shoulderfired weapons, most aircraft flying over 20,000 feet are safe from the threat; however, aircraft taking-off or landing are extremely vulnerable. A radiometric model was developed to simulate a large commercial aircraft’s infrared intensity during these two critical phases of flight. The radiometric model was largely based on the dimensions of a Boeing 747-400 aircraft. It is capable of simulating elevation angles between -20o and +20o, as well as 360o in azimuth in its projected area analysis of the faceted model. The model utilizes an obscuration matrix to determine which parts of the aircraft are in view by the observer and thus contribute to the aircraft’s intensity. A simple one-bounce reflection matrix was also included to incorporate reflections of hot parts off other body parts, as well as earthand sky-shine contributions to the overall intensity. Various atmospheric scenarios can be loaded into the model to incorporate atmospheric transmittance and radiance effects in the simulation. Measurements taken at the Air Force Research Laboratory’s Optical Measurement Facility are used to create material matrices which account for angle-dependent emissivity and reflectance. A graphical user interface (GUI) was developed to allow a user to change variables and view the resultant aircraft intensity as a function of elevation and azimuth