SAVOIA MARCHETTI SM.79
Talking about a famous aircraft like the Savoia Marchetti SM.79 isn't easy, a lot has been written about it and, more or less, everything has already been said. To do it in an article is even more difficult since it’s very complex to summarize the very rich and exciting history of such a legendary aircraft. Nonetheless the development history of the SM.79 looks rather simple, a handful of well defined steps brought about, in a natural way, changes in aircraft production and evolutions in its service.
HISTORY
he origin of this project came from
the necessity of reaching locations at
considerable distances while transporting
10 passengers at faster speeds than the other
transport planes of the time. Speed was
key, when engineer Alessandro Marchetti in
February of 1933 completed the first drawings,
the aircraft designated SM.79, already had its
trimotor elegant profile. Many structural and
aerodynamic characteristics promised great
performance, retractable landing gears, three
radial engines Isotta-Fraschini “750” Asso of
800 hp and Handley Page slots connected to
the flaps were some of them. In the spring of
1934 the aircraft, now ready, was given the
civilian code I
-
MAGO which means “wizard” in
Italian, a sign of things to come.
owever the first couple of flights were
rather disappointing, the speed, just
over 350km/h, was nowhere near what it was
supposed to be. The cause of the problem was
quickly identified in the engines,which just
weren’t powerful enough and were not ideal
for high performance. The solution was to
turn to Alfa Romeo, in particular to the Alfa
125 RC.35 which were license built Bristol
Pegasus.. The designation of the engine is
important,explaining the motivations of the
change. "R" stands for Radial, so an engine
with 9 cylinders in a star shape, "C" stands
for Compressor which means that the engine
had a single speed compressor, that would
enter in action only at a certain altitude in
order to rebalance power. With higher altitude
the progressive lack of oxygen causes
a substantial loss of power in the engines and
the compressor is needed to counter that loss,
compressing air and fuel thus injected in the
cylinders with higher pressure and energy.
Finally "35" (3500 meters) was the altitude
at which the compressor started working,
allowing the aircraft to keep its performance
even above this altitude. With the new engines
things changed quickly, the SM.79P broke
handily the 400km/h speed, a new record that
no other transport plane had ever achieved.
he aircraft was subject of numerous
tests from pilots of Roma-Guidonia then
started to be used for flights towards West
and East Africa as VIP transport. Those flights
were major records, completed without any
issues and at an impressive rate. Meanwhile,
military clashes were brewing in Somalia
and Eritrea, so these very promising outlooks
persuaded the SIAI to develop a military
version which had an increased autonomy and
military payloads such as bombs and machine
guns. Just as the first military versions came
out of the factory there was another change
in the engine, adopting the new Alfa 126 RC.34
which would go on to become the main engine
of the aircraft until the end of the war. By the
end of 1935 the aircraft had already completed
all the tests and real bombing runs, while,
sadly, the political and military situation in
Spain was worsening, turning into a civil war.
AVOIA MARCHETTI
S
M.79
FROM TRANSPORT PLANE
TO DARING TORPEDO MISSIONS
Maurizio Di Terlizzi
Talking about a famous aircraft like the Savoia Marchetti SM.79 isn't easy, a lot has
been written about it and, more or less, everything has already been said. To do it
in an article is even more difficult since it’s very complex to summarize the very
rich and exciting history of such a legendary aircraft. Nonetheless the development
history of the SM.79 looks rather simple, a handful of well defined steps brought
about, in a natural way, changes in aircraft production and evolutions in its service.
T
T
H
INFO Eduard18
February 2024