ESDU 89021 sets out the basic equations used in ESDU 89023 to 89027 which present temperature distributions, and stresses and moments, in various structural elements due to aerodynamic heating on the exposed faces. The equation is given for the temperature distribution through thick sheet heated by forced convection on one side and insulated on the other. Then the equations are given for the stresses and moments on a plate with completely restrained edges; the effects on those equations of relaxing the constraints are considered, firstly to completely free edges and then to edges either free to expand only in the plane of the plate or free to expand in the plane of the plate and rotate.