FIRST STEPS TOWARD SPACE - Smithsonian Institution Libraries

266 SMITHSONIAN ANNALS OF FLIGHT
ing to information of questionable accuracy given
to Unge by Krupp.
After the unlucky affairs with Krupp, Unge continued
his experiments with lifesaving rockets,
which had begun in 1907. The work was based
upon two patents, one for a new ignition system
and the other for "improvements in or relating to
the means for connecting lines, cables or the like to
rotatory projectiles for conveying them through the
air" (Swedish patent 26,991, received in 1908). Test
launchings were made not only in Sweden but also
in England for the Board of Trade, and Unge managed
to sell some of these life-saving rockets (Figure
10) to England, India, Australia, and Greece. The
weight of the system, including one rocket (based
upon the 10-cm rocket), 400 m of line (400 yd), lineholder,
and the transportation box with launch
barrel was 105 kg (230 lb). The usable range was 300
m (900 ft) with very good accuracy, even in storms.
The price for a set-up was 80 to 100 dollars.
Unge spent a lot of effort on improving manufacturing
methods. A way to make a more inexpensive
rocket body was introduced in 1912. The
cartouches, the turbine, and the forward wall of the
combustion chamber were pressed together into the
final form of the propellant charge by means of a
hydraulic press, and then a steel band was wrapped
around the propellant and fastened at the ends to
the turbine and to the forward wall by screws.
Another idea, tried with great success, was the
manufacturing of a very inexpensive turbine out of
clay. Most of the smaller rockets tested after 1912
were produced with the clay turbine. The turbine
was also modified to provide greater thrust by
means of a conical hole in the central portions of
the turbine. The dimensions of the 10-cm rocket
FIGURE 10.—Complete lifesaving rocket system, manufactured by the Mars Company. Photo from
Armemuseum Archives, Sweden.