Group shot of Bulgarian airmen in front of KB-5 No.18 parked on the concrete at Balchik airfield in Southern Dobruja. The life vests denote that the aircraft was assigned to reconnaissance duty along the Black Sea coast at the time this shot was taken in 1941. Note the Luftwaffe He 111 and Ju 88 in the background.

KB-4 No.19 in pro-Allies markings, in effect from early September 1944. They consisted of a white rear fuselage ring and wingtips on the top surface of the upper wing and bottom surface of the lower wing.

Two KB-4s during service with the VNVV training unit in 1939. Chuchuliga IIs were the first SFBK-made aircraft delivered with full military markings.

The first KB-11 prototype presented a mid-wing configuration and a robust undercarriage. Due to its peculiar appearance, the aircraft was unofficially named 'Quasimodo'.

Второй опытный экземпляр КБ-11
The second KB-11 prototype featured a high-wing configuration, as well as a largely redesigned cockpit and undercarriage. Depicted is the last unit of the small series, No.7, delivered in 1941.

КБ-11А 2-й серии с мотором "Пегасус" XXI
The final version of the KB-11 featured redesigned fuselage glazing and was fitted with yet another powerplant, driving a two-blade wooden propeller. No.25 has a well-worn appearance, except for the engine cowling and tail surfaces, freshly repainted possibly to cover the outdated pro-Axis yellow recognition marks.

Fifth production KB-6, No.5, handed over to the VNVV in the spring of 1941, as denoted by the wrap-around yellow engine cowling - a mandatory Axis recognition feature during the attack on Yugoslavia and Greece.

Most ambitious project of the Balgarski Kaproni Works was the KB-6 twin-engined transport and light bomber.

LZ-CEA, the first of six KB-2As manufactured at Kazanlak, depicted soon after it rolled off the production line in 1936.

Aviation 'meetings' were popular events in Bulgaria of the 1930s. KB-2UT LZ-CTD participating in one such show, held over Kazanlak - home of the SFBK works. Note the white-green-red coloured ribbons attached to the outboard wing struts.

Factory photograph of the first KB-3, LZ-CIA. Note the characteristic 'hump' protruding between the two cockpits, added to the airframe to protect both airmen in case of a nose-over.

Close-up of the ’hump' introduced on the Chuchuliga I series.

A KB-2A, possibly LZ-CEC, caught during maintenance work in late 1930s. The engine's Townend ring had been removed. The name, Chuchuliga (Lark), is painted in white on the base of the fin.

Line-up of six factory-fresh KB-2UTs on the landing ground at Kazanlak, prior to the official handover ceremony in 1934.

KB-2UTs LZ-COF and LZ-COH parked near a lodge in the Sredna Gora (Middle Mountains), in Central Bulgaria. For operational service, wheel spats were usually removed to allow KB-2UTs to operate from rugged terrain.

First product of SFBK at Kazanlak was the KB-1 Peperuda (Butterfly), a distant relative of the DH.60 Moth. Illustrated is the KB-1 prototype LZ-COA.

Since the main task of Butterflies was basic training, there were frequent accidents. The lower wing's larger span is clearly visible on capsized LZ-COD.