The Study of Fuels

1957 March,

Except(s) from the paper “On the study of fuel storage in space and practical engineering concerns”

Since the purpose is increase the understanding of how fuels and tanks react in space, it is necessary to study the four primary fuel mixtures. These being Aerozine/NTO, UDM/NTO, Kerosene/Ox and H/Ox, especially the latter, as there are few 3 example of actual use. This is especially due to the boil off problems encountered, when the engines where first developed in 1955. Given just how good these hydrolox engines can be, its a primary objective to test, if these can be used effectively in some manner.

The final probe design had with two rings of 6 individual tanks. The tanks had an identical volume, but different weights. Some included extra features such as insulation, or active cooling. The first ring was dedicated to the three currently used fuels, and the second ring was dedicated towards different H/Ox setups.

Study of Fuels.png
Colorized picture of fuel study mission. The color/texture indicates tank type.

The first probe failed during circulation for reason unknown, but several smaller explosions where detected prior to the probe crashing back down into the atmosphere. The second probe did manage to reach a safe orbit mostly intact, two tanks exploded during ascent or shortly after reaching orbit. The reason is still not understood.

One hour after reaching space, we took a first snapshot of all data, we measured the following data:

Fuel Type Dry Mass Wet Mass Result (1h)
Aerozine/NTO Ballon 0,2136kg  14,97kg No loss
UDM/NTO Ballon 0,2136kg 15,01kg No loss
Kerosene/Ox ServiceModule 1,3610kg 14,25kg 0,25% O2 lost
Kerosene/Ox Default 0,3680kg 13,25kg All O2 lost
Kerosene/Ox BallonCryo 0,2072kg 13,10kg 1,24% O2 lost
Kerosene/Ox Cryogenic 0,3831kg 13,27kg 1,00% O2 lost
H/Ox Ballon 0,07615kg 4,396kg Exploded in orbit
H/Ox Ballon + Rad* 0,07615kg 4,396kg No loss
H/Ox Cryogenic 0,2896kg 4,609kg  11,32% H2 lost
H/Ox Cryogenic + Rad* 0,2896kg 4,609kg No loss
H/Ox BallonCryo 0,1137kg 4,433kg Exploded during ascent
H/Ox ServiceModule 1,2570k 5,577kg 2,56% H2 lost
0,0?% O2 lost

Rad* = Large flat radiator linked directly to the relevant tank.



Note from 1.2.2 (updated on 3/10 2017, Real Earth)
This study now no longer represents the game reality… Cryogenic tanks no longer work, however ServiceModule is almost evaporation proof. Sigh.



One comment

  1. This matches my initial tests, although they haven’t been done with quite as many tanks. Also, protecting them behind a fairing during the ascent should make them less prone to RUD.

    Cryo-tank plus radiator is required, otherwise something evaporates. Oddly enough, I also concluded that LOx only evaporates if there is no LH present.

    Further engine tests have so far also indicated that LH-LOx engines don’t seem to suffer from ullage issues?

    Same tests as the engine ones done on LEO probes also indicated that the rate of loss slowed as the tank became more and more empty?


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