RAMAC in subdetonative propulsion mode: State of the ISL studies

Abstract

The RAMAC is an aerothermochemical launcher aimed at accelerating a projectile up to hypersonic velocities under smooth conditions. In most cases, the ram tube is a smooth cylindrical bore, filled with a dense gaseous reactive mixture in which is injected a supersonic under-calibrated projectile. The mixture composition and projectile shape are two key-elements for the success of the ram process. Composed preferably by an axisymmetric biconical body guided by fins, the projectile shape has been designed in order to control the flow expansion once it has been compressed at the nose, to trigger the combustion and control its appropriate location at the rear of the projectile in the thermally choked propulsion mode, also referred to as subdetonative propulsion mode. Two smooth-bore experimental tools, a RAMAC 30 and a RAMAC 90, in 30 and 90 mm caliber respectively, are alternately used with the same gas handling, gas chromatography and data acquisition system in order principally to study the scaling effects. These two ram facilities recently received some important modifications among which the installation of new preaccelerators allowing enhanced RAMAC entrance performances, i. e. the launching of higher masses at the same initial velocity of about 1340 m/s.