FIRST STEPS TOWARD SPACE - Smithsonian Institution Libraries

NUMBER 10 15
FIGURE 11.—Experimental facility at Satory for static-test firing of rocket engines.
Figure 12 shows the system for cooling the nozzle
by circulation of the liquid oxygen before its introduction
into the thrust chamber. The latter was
made of duraluminum and contained a block of
pure copper into which were screwed six pure
copper premixing chambers. The latter were
equipped with four rings of jet holes.
The nozzle was made entirely of pure copper, and
its outer surface had longitudinal 30° grooves
which, while doubling the surface wetted by the
oxygen, provided sufficient passage for the latter
even in the case that the nozzle, when expanding
to regulate the thickness of the cooling sheet of
liquid oxygen would touch the outer ring (A).
The fuel arrived under pressure at B and, passing
through the circular feeder (C), escaped by
290 small triangular slits cut 0.5 mm into the
upper part of ring D, and wet the external surface
of the nozzle. The flow around the nozzle is controlled
by ring A, whose cylindrical bore was
threaded so as to provide a rough surface that ensured
a constant pressure drop. The dimensions of
the oxygen passages, that is, the relative positions
of the nozzle and rings A and D, had been previously
adjusted according to the results of water-flow
tests.
None of the three tests was successful, and REP
abandoned the idea of cooling by liquid oxygen.
The reason for his efforts to cool the nozzles in this
way was that he feared it would not be possible to
operate without cooling.
6. Uncooled refractory nozzles.—At the end of
1936, REP began to work on nozzles made of ultrarefractory
materials. For this purpose he built an
electric furnace of his own design. After many difficulties
due to the outdated equipment he was
obliged to use because of lack of money, and after
many experiments 64 he managed to make convergent
parts of nozzles to the following dimensions:
a cylinder 50 mm in diameter and 20 mm
thick having, along its axis, a hole of which the
diameter converged from 35 mm at the entrance to
17 mm at the throat. At that time his tests normally
lasted 60 seconds. In order to fabricate with
this furnace the nozzles needed, he had in vain
asked the Caisse Nationale des Recherches Scienti-