ESDU 69009 is concerned with the heat balance for flight vehicles and acts as an introduction to the group@ ESDU 69010@ ESDU 69011 and ESDU 69012@ dealing with heat transfer and kinetic heating. The factors affecting the skin temperature of a flight vehicle are listed and discussed@ leading to the setting up of a heat balance equation for a high speed vehicle. Its solution under steady state conditions is considered in ESDU 69012. The phenomenon of aerodynamic heat transfer is discussed and the associated quantities stagnation temperature@ temperature recovery factor and recovery temperature are introduced@ together with equations for their evaluation. Finally@ the non-dimensional heat transfer parameters Nusselt number and Stanton number and the relationship between the latter and skin friction coefficient are defined. Stanton number data for two-dimensional flat plates with a laminar boundary layer are given in ESDU 69010 while similar data for a turbulent boundary layer are given in ESDU 69011@ both sets of data being obtained via an appropriate Reynolds analogy factor.