Cubic fuels?

The cubic molecules C4O4, N-8, and Si8R8 are considered as possible high-en ergy propellants. The potential energy surface minimum for C4O4 is found to be incapable of supporting any bound vibrational levels. N-8's decompositi on to 4 N-2 is mapped in detail, but the initial barrier of its rather comp licated dissociation is too modest to allow hope for its handling in bulk q uantity. Si8H8 is found to be the most promising additive among the four R' s considered, but simulation of its combustion in an LH2/LOX rocket gives o nly a 6-s specific impulse enhancement. (C) 2000 John Wiley & Sons, Inc.