FIRST STEPS TOWARD SPACE - Smithsonian Institution Libraries

NUMBER 10 225
the first attempt failed on 10 May 1931, it was
launched on 14 May 1931, and climbed to an altitude
of 60 m. Thus, two months after Winkler's
rocket had been launched, a second successful
launch of a liquid rocket in Europe took place and
demonstrated the flying capability of the Repulsor.
As to the cooling, a few problems still remained.
Ley described the situation in Manner der Rakete:
". . . The rocket took off well, but immediately hit
some trouble . . . and made several loops in the
air. The cooling water ran out of the container,
which was open on top, and the engine burnt
through." 17
Up to June 1931, three models of the Zweistab-
Repulsor were tested and launched; they did not
differ much from one another.
In August 1931, the first launch of an improved
model, the "Einstab-Repulsor" (one-stick thruster),
took place. The rocket reached a height of 1000 m
on the first launch. It resembled a four-pronged fork
with prongs placed upward and the handle formed
by the lox tank. Two of the prongs were propellant
lines and the other two were braces. The fuel tank
was arranged in line with and below the lox tank.
Under it, near the tail fins, was the container for
the parachute. Mounted on top and supported by
the four prongs was the old engine surrounded by a
jacket filled with non-circulating cooling water.
The tests with the Einstab-Repulsor were extremely
successful.
The May 1932 edition of the journal Raketenflug
included the proud announcement: "Up to May
1932, the Berlin Rocket Field can claim 220 static
tests and 85 launches of liquid-propellant rockets.'
In spite of these impressive figures, the activities on
the Rocket Field had reached a climax with the
deevlopment of the Repulsor; during 1932, the crew
began to disperse. Johannes Winkler and his first
assistant, Rudolf Engel, were the first to transfer
to the newly founded Raketenforschungsinstitut-
Dessau (Dessau Rocket Research Institute). A few
months later, on 1 October 1932, Wernher von
Braun accepted employment with the Heereswaffenamt
(Army Ordnance Department) which asked
him to carry out experimental work in their Sub-
Office for Rocket Development under the direction
of Walter Dornberger.
Work on the Rocket Field under Nebel and
Riedel still continued. Besides flight tests of various
Repulsor models, the design and development of a
larger rocket engine with 64-kg thrust were started
in April 1931. To distinguish it from the smaller
egg-shaped Repulsor engine, Ley called it the
"Aepyornis-Ei" (Giant Ostrich Egg). Tests of this
engine, using 0.8 liter of gasoline and 3 liters of lox,
were unsatisfactory with respect both to thrust and
cooling. Again, static cooling had been applied, but
was not sufficient for these much bigger engines.
The decision was made to develop an engine for
250-750 kg of thrust with regenerative cooling, using
fuel as coolant. Also with respect to the fuels, variations
were tested. In winter 1931 Riedel had already
thought of using a water-alcohol mixture which
Oberth had proposed. He hoped to maintain tolerable
chamber temperatures without too greatly
diminishing the performance, as is the case when
gasoline is burned oxygen-rich. Preliminary tests
were run between August 1932 and March 1933
with gasoline and also with alcohol-water mixtures
of 40 to 90 percent alcohol. Construction of the
engine began, according to a report by Herbert
Schaefer, a colleague at the Rocket Field, about
Christmas 1932. 18 On 9 March 1933 the new engine
was tested for the first time on a provisional test
rack. During March and April 1933, a new test
stand for 1000-kg-thrust rocket engines was finished,
and a series of tests with eight models was started.
On March 25 and April 3, the first and second
models, respectively, exploded immediately after
ignition. During April about 20 additional tests
were run and produced good results, providing
thrusts of 150 to 200 kg.
In autumn 1933, Riedel and Nebel applied for
a patent on their method of regenerative dynamic
surface cooling. The application was declared secret
and filed under the No. 32,827 I 46 g. It could not
be determined whether national security, political,
or objective reasons prevented their being granted a
patent. But it is a fact that their inventive idea was
not new when the application was filed. In 1928,
Konstantin Eduardovitch Tsiolkovskiy had already
published a proposal for such a method of
dynamic regenerative cooling, and in Manner der
Rakete (1933) Tsiolkovskiy reported: "... Figure
34 shows a rocket motor of my own design that
was published in Technische Rundschau [Technical
Review], 1928, no. 31. The principle of pre-heating
the propellant in a cooling jacket surrounding the
chamber was used for this motor." 19 Moreover, in
1929, Alexander Boris Scherschevsky, a Russian stu-