FIRST STEPS TOWARD SPACE - Smithsonian Institution Libraries

14 SMITHSONIAN ANNALS OF FLIGHT
FIGURE 8.—Vibrating volumetric feed regulator.
3. Constant pressure drop jet.—This jet was
intended to ensure a correct mixture ratio with constant
pressure drop whatever the liquid viscosity.
Figure 9 shows the inner surface of the jet, which
is grooved. When the depth (b) of these grooves is
equal to the distance (a) between them, the flow is
independent of the viscosity of the fluid. Naturally,
this arrangement increases the pressure drop between
the tank and the combustion chamber.
4. Means of lightening tanks.—Light alloys
W
77/
FIGURE 9.—Inner surface of injector, showing grooves.
proved to be particularly good material for liquid
oxygen tanks because their mechanical characteristics
are better at very low temperatures. Since it
was not possible at this time to weld such alloys,
REP designed tanks of duralumin, using thin
rolled-up sheets and bonding successive layers together
(Figure 10). Because of the low quality of
the available adhesives, he did not continue his
efforts to perfect this method at the time, but the
idea was adopted very much later in other countries.
5. Firing tests at Satory.—A test stand was built
at Satory in 1932. It was used for engines delivering
thrusts up to 100 kg and later up to 300 kg. Exhaust
velocities of 2400 m/sec were attained in 1936.
Figure 11 shows this apparatus in detail. The
compartment on the left housed the petroleum
ether tank; that in the center, the engine being
tested; and that on the right, the liquid-oxygen
tank.
Each of the tanks was mounted on a recording
balance. The engine, with its jet directed downward,
was suspended from a dynamometer having a powerful
vibration damper that from the beginning
worked as REP had calculated. The successive tests
enabled the measurement of the time, the propellant
flow, the tank pressures, combustion chamber
pressure, pressure at the nozzle throat, the
engine thrust, and the inlet and outlet coolant
temperatures. These measurements were executed
automatically in the proper sequence by a mechanical
timer invented by REP. It should be noted that
this assembly worked correctly from the beginning.
It was necessary to add only an electric heater in
order to pressurize the oxygen tank. For cooling
REP at first used water.
A study of cooling by liquid oxygen was undertaken
next and tests were conducted on 15 October,
3 and 16 December 1936. 53
FIGURE 10.—Rolled and adhesive-bonded sheets for the
manufacture of tanks.