From Yugoslavia,
M.Mitrovich MMS.3 :twin boom light transport aircraft.
More Info from my files,
in
the 1930s, the Kingdom of Yugoslavia was not one of the world's major aircraft manufacturers, but despite this, several unusual and very interesting designs
were created in the country. In 1934, engineer Milenko Mitrović-Spirta,
technical director of the small Yugoslav aviation company Aeroput AD,
began designing a light four-seater passenger plane that could be used
for business, tourist, courier, mail transport flights, and also as a passenger
plane on short, rarely used routes.
The aircraft designed by Mitrović, designated
MMS-3 after the designer's
initials , was a twin-engine high-wing monoplane with an unconventional
twin-fuselage layout with a central fuselage gondola suspended under the
wing and two thin tail booms, which were extensions of the engine nacelles
placed on the wing. The ends of the tail booms were connected by a
horizontal stabilizer, on the center of which a single vertical stabilizer was
mounted. This aerodynamic layout was tested in detail by Mitrović in March
1934 in the Eiffel wind tunnel in Paris. The designer then tried several configurations, including those with inline and radial engines, without cowlings
and with cowlings, placed at different distances from the fuselage gondola.
The ultimately selected layout was characterized by an aerodynamic
perfection of about 12, at that time achieved only by very good gliders.
The aircraft had an all-wooden structure, covered with plywood and canvas.
The richly glazed cabin, housing the pilot's and three passenger seats, was
located in the central fuselage gondola. The passenger seats could be
removed, and in their place various loads could be carried. The aircraft
was eventually powered by lightweight British Pobjoy "Niagara" radial engines
with an output of 66 kW (90 hp), covered with NACA covers. The engines were characterized by low fuel consumption and very quiet operation, which
ensured great comfort for passengers. The fuel tanks were placed inside
the fuselage parts of the wings, between the central fuselage gondola and
the tail booms. The tricycle landing gear with a tail wheel was fixed, with
the main wheels supported by the central fuselage gondola and engine
nacelles, and the movable tail wheel was placed under the rear part of the
fuselage gondola. The main wheels were covered with fairings, but the plane
often flew without them.
Work on the construction of the MMS-3 prototype began in mid-1934 and
was completed only at the end of 1935. The aircraft was built at the Aeroput company's own expense in Zemun near Belgrade. The aircraft's first flight
was carried out at the end of January 1936 by Aeroput's chief pilot Vladimir Strizhevski. Flight tests confirmed the initial design assumptions - the aircraft
had good performance and was very stable in flight throughout the entire
speed range, even with one engine switched off. In the summer of 1936, the aircraft received a certificate of airworthiness and the YU-SAR registration.
From that moment on, the aircraft began to be used in the Aeroput colours for transporting mail, press and business flights on routes to Sarajevo, Podgorica, Skopje, and many other smaller cities. During one such flight on the Belgrade-Podujevo-Skopje route on September 15, 1936, the plane suffered an engine failure and pilot Rodoljub Milovanović had to make a forced landing. The
slightly damaged machine was quickly repaired and by the end of 1937 it
had spent a total of 65 hours in the air, in 1938 - 79 hours, and in 1939 - 102
hours.
In 1940, the MMS-3 was used for testing the nose wheel landing gear. At that
time, Eng. Mitrović and Prof. Dr. Eng. Miroslav Nenadović were working on a project for a twin-engine light bomber and reconnaissance aircraft provisionally called
NEMI , which was to have a similar aerodynamic system to that used in
the MMS-3, but a three-wheel landing gear with a nose wheel. However, this project was never implemented.
In March 1941, in view of the tense international situation around Yugoslavia,
the MMS-3 aircraft was taken over by the Yugoslav Air Force JKRV and incorporated into the 603. Pomocne Eskadrile (auxiliary squadron), where it
was to perform liaison, dispatch and courier tasks. Its further fate after the
German attack on Yugoslavia in April 1941 is not known in detail. However, according to eyewitness accounts, the aircraft was destroyed by its own
crew on a landing field near the village of Divac in the Valjevo region.
Before the outbreak of the war, the MMS-3 aircraft had aroused considerable interest in various countries, including France, Great Britain, Germany, and Czechoslovakia. There were even preliminary talks about selling a license for
the MMS-3 by Aeroput, but nothing came of these plans either. Ultimately,
only a single prototype remained in existence.
