Boron containing propellants for ramjets - an area of great current interest

In future air-to-air missiles for the Swedish defence, ramjet engines with solid boron propellants are a very probable motor alternative. It is important to collect as much relevant information as possible and to up-date our knowledge in this field of great currency. This report is based on information from the open literature. It gives a short background to the use of boron propellants in ramjets and is meant to be an aid for evaluating different propellants. Basic data as well as basic relationships have been summarised. Recent research in the area has been reviewed. Boron is a highly energetic fuel and has a high potential as a performance-increasing additive in ramjet fuels. It has, however, shown to be difficult to prepare useful boron propellants. Boron involves problems at manufacturing, initiation and combustion. Granulation of the boron particles seems to be an efficient way to reduce these problems. A simple analysis shows that ramjets with solid boron propellants, described in the literature, have a considerably lower regulating range of fuel, compared to ordinary hydrocarbon-fuelled liquid ramjets.