FIRST STEPS TOWARD SPACE - Smithsonian Institution Libraries

228 SMITHSONIAN ANNALS OF FLIGHT
The first test, on 21 December 1932, was a failure.
The engine and test rack burnt out after a detonation.
A smaller version of the 300-kg combustion chamber
had already been ordered in 1931 from the
Heylandtwerke, according to Dornberger's account.
Cylinder-shaped, it had been designed for a thrust
of 20 kg, with double iron walls for cooling purposes;
thus, most likely, the first combustion chamber
with regenerative surface cooling was built in
1931 by Heylandt. Toward the end of 1933, after a
series of significant modifications but without
fundamental changes in the cooling system, the
300-kg engine finally operated and developed exhaust
velocities up to 1800 m/sec in static testing.
For the rockets following the A-l with its 16-sec
burning time, engines with longer operation times,
higher performance, and better cooling systems had
to be built. The 1000 kg engine of the A-2 rocket,
however, that reached altitudes of more than 2000
m during the first launches in December 1934, did
not show any significant modifications compared to
the A-l.
Subsequently, between the groundbreaking ceremony
for the new test facilities in Peenemuende in
August 1936 and the first test firing of the A-3 from
the new test area in December 1937, the new A-3
rocket with a height of 6.5 m and take-off weight of
0.75 tons was developed; there also was developed
by Wernher von Braun, Walter Dornberger, Walter
Riedel, and Walter Thiel, in close cooperation, a
new and considerably improved engine developing
a thrust of 1500 kg. The modifications included an
improved injection system with centrifugal injection
nozzles, a mixing chamber between injection head
and combustion zone, and improved gas flow
through conical form of the lower part of the
combustion chamber. But, again, cooling problems
increased with improvements in performance and
rise of combustion chamber temperature in the
1500-kg engine.
During the development and construction of the
next prototype, a 4500-kg engine, using an assembly
of three injection heads from the 1500-kg engine in
one combustion chamber, one of Thiel's associates,
Wilhelm Poehlmann, suggested a decisive innovation.
Dornberger described this event as follows:
Yet the motors still burned through, from time to time, at
points along the wall or at the throat of the nozzle. Dr.
Thiel's engineer colleague, Poehlmann, made a useful suggestion:
How would it be if a sort of insulating layer were
formed between the heat of the combustion gas and the
wall? If we sprayed the inner wall of the chamber with
alcohol, it would of course evaporate and burn, but the
temperature of this layer could never equal that inside the
chamber. Such was the origin of film-cooling. A large number
of small perforations at the endangered sections admitted
alcohol to the motor and especially to the exhaust nozzle
under slight differential pressure. The holes in the wall were
filled, after drilling, with Wood's metal, which melted as
soon as the flame formed, thus allowing the cooling alcohol
to enter. 2 4
The first large 25-ton engines which were tested
in spring 1939 on test stand 1 at Peenemuende,
used this new cooling process. Thus, after 15 years,
in 1938, an idea first proposed by Oberth in his
famous book Die Rakete zu den Planetenrdumen,
had finally been realized. On 3 October 1942, the
first successful launch of an A-4 rocket provided the
climax of this development and represented an
important milestone.
Work of Eugen Sanger in Vienna
In a curriculum vitae presented in 1934, Eugen
Sanger wrote:
During physics classes in high school we were at times
introduced to the field of rocketry. After 1926, when the use
of rocket propulsion for very fast stratosphere airplanes had
been recognized as feasible, I began to study this problem
more seriously.
In August 1931, Sanger started to summarize his
occasional studies and their results in the form of a
book published by R. Oldenbourg, Munich, in the
spring of 1933 under the title Raketenflugtechnik
(Technology of Rocket Flight). Having temporarily
completed his preliminary theoretical studies,
Sanger began in 1933 to conduct experiments at the
Technische Versuchsanstalt (Technical Research
Institute) regarding the selection of materials for a
reaction motor. In autumn of 1933, he proposed to
the Verband der Freunde der Technischen Hochschule
Wien (Society of Friends of the Technical
University of Vienna), a brief, well-defined program
for "Model Tests with Uniform-Pressure Rocket
Engines." In addition, a program for the practical
development of rocket flights was set up and presented
to the public. Actually, the true inspiration
for Sanger's work in the field of spaceflight and
rocketry had been a science fiction novel that he had
received on 7 February 1919, at the age of 13, as a
gift from his physics teacher, Dr. Gustav Schwarzer.
It was the book Auf zwei Planeten (On Two