Although a number of infrared models are available for synthesizing the infrared image of static objects, they fail to simulate the infrared signature of targets flying at high speed. This paper presents an infrared image synthesis model for such kind of targets. Within this model, we account for not only all forms of heat transfer inside the targets but also the dynamic interaction between the target's surface and the surrounding air-flow. The heat transfer process between the target's surface and the air-flow is carefully analyzed based on the principles of infrared physics, aerodynamics and heat transfer, and a term due to aerodynamic heating is incorporated into our new model. Experimental results illustrate the potential of the model