Bulgarski Kaproni KB 309 Papagal (Parrot)
The KB 309 was basically a license built aircraft at the Kazastak factory of the Italian Ca 309.The original Ca 309 aptly named Ghibli (desert wind), 78 of which were built between 1936-1938 for use in Libya. There were two civil examples and 165 built for the Regia Aeronautica during the war years. Two were supplied to Paraguay in 1938. When Italy entered the war in 1940 there were seven squadrons equipped with the Ghibli.
The Bulgarian built version, the KB 309 started its test flight on the 28th November 1940. The original features of the Italian Caproni were retained. These comprised mixed construction and fixed landing gear. The principal difference on the KB 309 was the power plants. The original low power Alfa 115 was replaced by the German Argus AS 10C. This was a 240 hp air-cooled 8 cylinder inverted ‘V’ engine, which was identical power plant used on the FW-58 B/E. The Papagal KB 309, was also commonly known or the KB-6 and was the only twin engine type to be made in Bulgaria. The new power plant increased the power by about 30% which resulted in improved performance such as rate of climb, and also increase in service ceiling of 21,325 ft, being attained as against 13,945 ft with the original Italian engines.
The KB 309 had a cabin for six passengers and fitted with windows on both sides. Other minor modifications included a 10 cm longer fuselage, a reduced lower fuselage tail end which involved a small reduction in the lower fin and rudder area. There were minor changes to the leading edge at the wing root area, removal of fairings on the main landing gear, and a redesigned nose with transparent glazing. Nine examples were built having serial numbers 1/7024 to 9/7024. The Papagal remained in service for seven years up to the late 1940s during which it was used as a trainer, ambulance plane, and liaison duties and on occasions also as a light bomber where it was armed with a 7.7mm machine gun, two of which were fixed in the wing root and could carry a bomb load of 660 Lb. The recce version was equipped with a camera in the nose.
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There is only one known kit of the Caproni 309 at the scale of 1/72, which is now hard to find and was released by LF Models, a resin kit. In the understanding that the Ca 313 evolved from the earlier Ca 309 and Ca 310 variants, a study of scale plans of the two aircraft types gave good indications that the Italeri kit of the Ca 313 could be used to produce the Bulgarian KB 309 which was a direct development of the Ca 309. More recently the Caproni 310 by Azure also appeared on the market and can be an alternative model to use for the conversion into a 309. The KB 309 was not the type that mainstream kit manufacturers, or those from the cottage industry could ever throw their efforts to produce since the type was moderately successful, poorly armed and therefore not so known in combat service and few were built to the Bulgarian Air
Force. Yet no Bulgarian Air Force collection will be complete without presence of the KB 309.
The 1/72 scale model of the Ca313 by Italeri is a good quality product and was used as the scale model to produce the KB 309 with necessary modifications. The Italeri kit is well molded with good surface detail. The principal difference concerns rebuilding the forward fuselage, modifying tail fin and rudder, altering the in line engines, changes to the upper fuselage, building a new undercarriage, fixed type; new main cabin interior arrangement and other minor alterations to the cabin glass house.
It had an equally capacious fuselage and careful study showed the slight variation in fuselage side glazing. The pilot / crew office were assembled as indicated in the instruction sheet. The interior bomb racks were removed, ventral gun positions blanked and the interior rebuilt to accommodate seats for the 6 passengers mounted on a new floor made out of plastic card. The interior and bulkheads were painted green, seats were brown. A new landing gear was constructed from stretch sprue with a fork type end to hold the undercarriage wheels. A metal spring detail was added to upper part of struts resembling that of the full size aircraft. These are left to be cemented in place at a later stage. The forward fuselage was partly shaped out of balsa wood and partly from moulded Perspex to bring out the nose
glazing. These required frequent checking with scale plans produced from reference sources until the graceful characteristic of a semi solid fuselage was produced. A custom made camera was inserted into the nose. The engines were reshaped, as were also the exhaust stacks.
The assembly of the wings to the fuselage was a rather unique one in that the slots are incorporated in the wings with the tabs on the fuselage. The rear fuselage was reshaped and rebuilt with filler until the final shape of the KB 309 emerged. Smooth sanding of the area (with the glazing being adequately masked) followed this. Small detail as the antenna at upper fin and at mid fuselage were added at this stage and rigged wires added to vertical fin to forward fuselage. For this I have used invisible thread that was anchored to a tiny hole at mid fuselage. With the cockpit painted to the interior, I added the canopy to fit in place.
Color and markings
In conformity with other aircraft serving with the Bulgarian AF at the time a two-colour camouflage was applied. This consisted of Dark green RLM 70 to all upper surfaces and RLM 65 light blue to all under surfaces. Identification yellow was applied to under wing tips and mid fuselage band, and also to the vertical rudder. The yellow areas were first applied over an undercoat of white. These were then masked and the light blue underside was then airbrushed. Allowing several hours to dry, a 3/8-inch roll length of plasticine was applied to the fuselage side and the lower areas masked with paper and tape. The plasticine was to provide a feathered edge between the upper green and lower l blue. The upper were then airbrushed in RLM 70 dark green. After adequate drying time the masking was carefully removed and the kit was given a coat of
‘X’ style Bulgarian markings were acquired from decals that came with the Heller kit of the Me-108 which were exactly the correct size. Black outline was applied to the white square markings as this was missing from the Heller decals. (These were correct for the 108). With clear Perspex areas masked again, the kit was given a clear coat of semi matt Lacquer.
This kit builds into a pleasing replica of an unusual subject, which is not as well known or documented, as it may deserve to be. It will certainly make an interesting talking point when seen at exhibitions. There are good pictures of the Caproni 309 at the Plovdiv aviation museum that I happened to visit in June 2013.
Carmel J. Attard
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