Kerosene, hydrogen or methane? Trade-off analysis of ballistic design efficiency of fuels for launch vehicles of limitary volume

Based on an unsolicited trade-off analysis conducted by RSC Energia specialists of statistical data on characteristics of a large number of existing rocket stages for domestic and foreign medium, heavy, and super-heavy launch vehicles (LV) that use oxygen oxidizer, the paper presents comparative estimates of ballistic efficiency of various types of fuels for rockets of a limitary volume, that is, for rockets that have their structures limited by dimensional envelopes. These estimates demonstrate that for medium LVs of the Zenit LV type hydrogen is significantly inferior to kerosene in terms of ballistic efficiency. Methane is close to kerosene in ballistic efficiency, but is considerably behind high-energy hydrocarbon fuels (such as Boctan or the earlier Syntin). The analysis conducted for the US Delta 4 Heavy LV running on oxygen oxidizer and using hydrogen as its fuel (due to the fact that US does not have powerful and efficient oxygen-kerosene engines), showed that the use of hydrogen was not optimal from ballistic standpoint.