Modern KE-penetrators have penetration capabilities approaching one meter (in armoures steel) which calls for very advanced armour solutions and countermeasures. The success of sensor activated countermeasures is highly dependent on the accuracy of the sensors, providing accurate data on both position and velocity of the incoming threat. The range, velocity and trajectory parameters are estimated from the signatures of the projectile itself. Of particular interest are infrared (IR) signatures, more precisely a particular band in the radiation field. The IR signature depends on the temperature and the composition of the flow in the immediiate vicinity of the KE-penetrator, i.e. in the boundary layer of the projectile. In order to understand the physics behind the flow around high-speed projectiles in general, and KE-projectiles in particular, and to explain the nature of hypersonic projectile aerodynamics, a compressible Navier-Stokes solver has been developed for hypersonic aerodynamics. This code solves the Navier-Stokes equations including turbulence and shock-waves using a second order accurate finite method. The code has been validated against experimental data on the flow past a hemispheric body. To study the flow around KE-projectiles simulations have been undertaken for different Mach numbers, and the flow has been carefully investigated, with particular emphasis on hypersonic aerodynamics including aerodynamic heating, dissociation effects and IR-signatures. Results, such as these, can be used to improve the design of Swedish weapons and to evaluate the characteristics of potential threat projectiles - present or under design.