Abstract: The present invention relates to a strut assembly which may be selectively projected and retracted with respect to associated structure of a solid or liquid propellant rocket of missile, with such structure comprising one of, for example, a nozzle thereof or the body thereof. The invention struct may be projected either internally of the nozzle or externally of the missile body, as desired. Projection and retraction of the strut are accomplished through use of fluid actuation means, the fluid mode of means of which comprises coolant which is also directed in various locations on the inventive strut assembly to cool the strut assembly and to protect it and adjacent structures from particulate impaction, heat and thermal damage, etc.