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National Advisory Committee for Aeronautics, Technical Notes - Is There Any Available Source of Heat Energy Lighter gas Gasoline?

The weight of gasoline consumed, plus the weight of the tanks,
reaches the weight of the engine itself inabout five hours' flight
with a fixed engine, or in a much shorter period with a rotary en—
gine. Any reduction in the weight of the fuel is, therefore, bound_
to prove advantageous. The possibility of reducing the consump—
tion per HP—hour will not be considered, but merely the possibil—
ity of finding lighter sources of heat energy.

Of the hitherto exclusively employed fuels, which burn by com—
bining with atmospheric oxygen, gasoline appears to be the best,
since benzol has a lower calorific value. From the technical point
of View, the chemical composition of gasoline is about 85% C and
}5% H. This gives, as a conservative estimate of the heat value,
81 x 85 + 287 x 15 = 11190 kilocalories. The composition of refin—r
ed petroleum (kerosine) does not differ much from that of gasoline.
Benzol is 92% G and'8% H, which gives a heat value of

81 x 92 + 237 x 8 = 9748 kilocalories.l
The heat values of both, as determined by calorimetry, are some:
what lower; for gasoline about 10000, for kerosine about 10800,
and for benzol about 9590(kilocalories or greater calories). This
difference, in comparison with the heat values calculated on the

basis of the chemical combination of the elements, permits the
* From Technische Berichte,V8llIII, No.3, pp. 74—75. (1918),
conclusion that there are exothermic compounds in these hydrocar-
bons.

From the details of the calculation, it is seen that hydrogen
with 387 k—cal per 0.01 kg is of greater significance than carbon
' with 81 k-cal, suggesting at once that we must adhere to compounds
rich in hydrogen, or look for endothermic compounds in Which, when
the atoms are separated by combustion, the heat absorbed in combie
nation is given off at the same time. The possible effeofi 0f the
latter circumstance is illustrated by acetylene (CZHQ) which:
with the same proportional composition as benzol (CSHS), has a
heat value of 11600 cal. It is in fact, raccqmpcund capable 0f
disrupting explosively.