Rocket propellants energy efficiency

Although modern chemistry allows development of even more effective rocket propellants, energy efficiency is not the only consideration factor. For example, fluorine and its derivatives arc better oxidizers than oxygen, but their extreme toxicity make them environmentally dangerous. The same concerns prevent the use of beryllium hydride—an excellent fuel that combines high density with the energy efficiency comparable to liquid hydrogen. 

The latent energy of the peroxide was used to propel the V-l and V-2 rockets. As an efficient accumulator of oxygen it was also used for the combustion of fuels (tetrahydronaphtalene or a mixture of methanol and hydrazine hydrate)... 

The experimental discovery of Ns" salt stimulated a number of theoretical studies. Bartlett and colleagues [136] studied the stability of salt. It represents a potential solid nitrogen rocket fuel that would be much more efficient than currently rocket propellant. Unfortunately, due to the unavailability of Ns", a direct experimental test of this ion pair is not feasible. The stability of another ion pair, Ns s", has been investigated by Kortus et al. [137]. Unlike Ns s" for which a stability minimum was predicted as two-ion-pair clusters, the Ns" N3" ion pair can spontaneous isomerize to azidopentazole with lower energy and the latter will decay to molecular N2 spontaneously [137]. More recently, using ab initio molecular orbital theory, Dixon et al. [138] predicted that neither the Ns s" nor the N5" 3" ion pair are stable both should decompose spontaneously into N3 radicals and N2. 

---