FIRST STEPS TOWARD SPACE - Smithsonian Institution Libraries

232 SMITHSONIAN ANNALS OF FLIGHT
throat. For the initial development it would be satisfactory
if the liner lasted for one flight (principle of ablation cooling)
and be replaced each time thereafter. ... A complete
combustion chamber wall with graphite liner can be built
according to the following scheme [a drawing showing a wall
section]. The porous graphite liner can also be replaced by
a porous carbon liner of higher mechanical strength and
another high-temperature chemically resistant material, such
as magnesium oxide, thorium oxide or the like. . One
should also investigate whether the wear of the combustion
chamber wall could be reduced by a fuel additive (perhaps
iron carbonyl, asphalt, etc.) which burns and leaves deposits
on the wall, as for example in internal combustion engines,
and thus regenerates the chamber liner. . . . Finally, methods
for cooling the chamber walls and nozzle throat have to
be developed. From the previous discussions it follows that
only the propellants qualify as coolants. Of these, liquid
oxygen must initially be eliminated; prior to its evaporation
it cannot absorb any additional heat, and evaporation must
not occur since only as a liquid can it be fed into the combustion
chamber at a tolerable power consumption. However,
one could take advantage of the fact that an increase in
pressure raises the saturation of the liquid oxygen and
results in a temperature difference which would permit the
liquid oxygen to absorb a certain amount of heat; the liquid
oxygen, only after its discharge from the pumps, could be
passed through the cooling jacket of the thrust chamber, but
this method would necessitate extremely thick cooling-jacket
walls. . . .
The report also proposes three test series, the first
involving "small thrust devices producing 10 to 20
kilograms of thrust." Suggested test objectives of
the first series are:
1. Find suitable high-temperature-resistant materials for lining
combustion chamber and nozzle throat.
2. Determine magnitude of exhaust velocity and its dependence
on combustion pressure and mixture ratio.
3. Determine allowable ratio of propellant mass flow to combustion
chamber volume.
4. Find suitable configurations and structural materials for
building the nozzle.
5. Gather experience on auxiliary equipment.
As to the hardware of the first test series, the following
ground rules apply: weight does not matter; tapwater is used
to cool the combustion chamber, thus the chamber material
need not be a highly effective thermal insulator; external
energy drives the propellant pumps, etc.—or briefly, let test
objectives predominate.
In these initial proposals for methodical rocket
propulsion research, Sanger suggested that details
of the propellant coolant loop and the feed-pump
drive system be clarified only during the second test
series.
In December 1933, Sanger submitted to the
Austrian Defense Department a revised version of
his development plan, augmented by the preliminary
design of a liquid-oxygen-cooled rocket propulsion
system SR-2 which he described as follows:
The principle is that the diesel fuel flows from the tank
through the pump into the combustion chamber as a liquid,
whereas the oxygen passes as a liquid from the tank through
the pump, is forced (while evaporating) through the cooling
jacket passages, and enters the combustion chamber as a gas
of approximately 100° C. Thus the thermal stresses across
the injector elements are reduced and about 55% of the fuel
caloric value can be absorbed by the coolant.
This concept combined cooling by storing heat in
the liner with independent external cooling by
tapwater and forced regenerative cooling (oxygen
coolant channels).
By the way, shortly after the release of the development
plan in October 1933, the Viennese
journal Radio-Welt (Radio World), (No. 43, 22
October 1933) published for the first time for wide
distribution a design sketch of a rocket engine by
Sanger. The sketch did not contain any new items
on cooling methods or propellant feeding beyond
the original proposal of 5 January 1933, but instead
of a conical chamber it showed a spherical combustion
chamber with a Laval-type nozzle attached.
The first version of the research proposal
prompted Professor Rinagl to make available for
the first test runs some unoccupied buildings located
in the old "Bauhof," on Dreihufeisengasse near the
Electrotechnical Institute, which were modified in a
makeshift fashion to provide a test area open to the
outside and some sort of an adjoining operations
and observation bunker. Sanger also gained the
support of two of Rinagl's assistants, the Sztatecsny
brothers Friedrich and Stefan. With them he
founded a cooperative association which truly endured
the upcoming tough and critical months.
The trio proudly called the old shed in the Bauhof
"Deutsche Raketenflugwerft" (German Rocket
Flight Yard).
Less successful was Sanger's second version of the
research proposal submitted to the Austrian Department
of Defense, through Dr. Leitner, Superintendent
General. In early February 1934, the manuscript
was returned to Sanger with the following
reply:
Concerning your letter of December 26, 1933, you are informed
herewith that after evaluation of your rocket development
proposal the Department of Defense does not intend
to pursue this matter any further since the basic design
concept (use of liquid hydrocarbons and liquid oxygen)