ABSTRACT
An important strategy for improvement of propulsion system performance is
utilization of fuels and propellants that have signicantly enhanced energy den-
sity compared to normal hydrocarbons. For liquid-fueled applications, strained
hydrocarbons are a particularly appealing class of candidate fuel molecules,
because they should work in conventional combustors and fuel systems with
minimal modication. Their high-energy densities result mainly from increased
density compared to normal hydrocarbons; however, they can have up to
140 kcal/mole of strain energy built into the molecular framework in the
form of distorted bond angles. While this does not greatly increase the heat of
combustion, the strain energy changes the pyrolysis behavior of the molecules
substantially, which should make it possible to tune the ignition/combustion
Figure 4.1 Strained hydrocar-
bon molecules discussed in the pa-
per: (a) quadricyclane, (b) norbor-
nadiene, (c) cubane, (d) 1-azo-3-
ethylbicyclo[1.1.0]butane
ior might be substantially improved by
generation of reactive species early in the
combustion process or by micro-
explosions in fuel droplets. A few simple
strained molecules are shown in Fig. 4.1.
