FIRST STEPS TOWARD SPACE - Smithsonian Institution Libraries

38 SMITHSONIAN ANNALS OF FLIGHT
FIGURE 6.—Large fin-stabilized rockets, which used three tubular propellant grains.
isolated suite of two rooms which was assigned to
these tests at the Stabilimento di Costruzione
Aeronautiche (SCA), then on Viale Giulio Cesare.
There, assisted by Signor Laghi, an excellent technician
of the old school, I first carried out a series
of tests in the chamber shown in Figure 1, used as
a constant volume chamber by closing the nozzle.
iil^i^Y,
=0=t=^=ft
irlr\ XI
FICURE 7.—Test chamber for larger rockets.
I compared the performance of tubular charges of
the cordite used to that time, with a new doublebase
powder used by the Navy, the so-called Cpowder,
the composition of which is as follows:
Nitroglycerin
Nitrocellulose
Vaseline
Sodium Bicarbonate
Total
23.5
70.5
5.0
1.0
HJOlT
The first advantage I expected from the change in
propellant was related to the higher regularity of
the grain dimensions, a consequence of the different
manufacturing process. The manufacture of cordite
requires the evaporation of a solvent which must
be added to reach the necessary plasticity. During
the drying process the grain shrinks, with resulting
roughness of the surface and irregularity of the
dimensions. In the case of the C-powder the necessary
plasticity is attained by performing the operations
at 100°C without solvent; the surface of the
finished product remains quite smooth and the
dimensions quite regular. The second advantage I