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The Lazarov Laz-7 was a Bulgarian two-seater liaison and trainer aircraft of the immediate post-war era.
Its inception can be traced to April 1946 when Yugoslavia invited Bulgarian aircraft designers, namely those belonging to DAR (the main Bulgarian airplane manufacturer back then) to take part in a design contest for a new two-seater aircraft powered by a light engine water-cooled engine capable of yielding 140-160 hp of power.
Designed by Tsvetan Lazarov, chief engineer of DAR, in Yugoslavia, the Laz-7 was a cantilever monoplane with a low wing, a fixed-undercarriage and a two-seat glazed cockpit with the pilot and the trainee/passenger/observer sitting in tandem. It was equipped with double controls and was almost entirely made out of wood, with the exception of the engine.
It was powered by a single Czechoslovak-made Walter-Minor 6-III water-cooled engine, rated at 160hp of power.
On 20th August 1947 a production order was put and it wasn't until 10th June 1948 that the first prototype, Lazarov Laz-7.1 flew for the first time, with eng. Popganchev (a famous Bulgarian test pilot of the time) at the controls.
It was powered by a single Czechoslovak-made Walter-Minor 6-III water-cooled engine, rated at 160hp of power.
On 20th August 1947 a production order was put and it wasn't until 10th June 1948 that the first prototype, Lazarov Laz-7.1 flew for the first time, with eng. Popganchev (a famous Bulgarian test pilot of the time) at the controls.
After satisfactory flight-tests, the Laz-7.1 was sent to Belgrade, to honour the terms of the contest, and work on an improved variant, called Laz-7.2. This Laz-7.2 was equipped with an improved (and heavier) wing and was flight tested at the city of Karlovo, with almost identical results to those of the Laz-7.1. Those flights caught the attention of the Bulgarian Air Army and in August 1948 an order was placed for a two-seater trainer. However, as DAR was busy with another project, derived from the Laz-7, the Lazarov Laz-8, work on the Laz-7.3 (the production variant of the Laz-7) was delayed until May 1949, which made production runs to not be ready until September.
The Laz-7.3 had every improvement the Laz-7.2 had and was equipped with a backwards retractable landing gear. When retracted, half of the wheel was left uncovered, feature which turned to be very useful in case of a belly landing. Unlike both Laz-7.1 and 7.2, where main pilot sat at the rear and the trainee at the front, in the Laz-7.3 the main pilot sat at the front, so he could have a better firing angle, as the Laz-7.3 was the first variant to be equipped with weapons. These consisted in two 7,7 mm M-30 machine guns mounted in the wings or one 7,92 mm T6-200 machine gun. It could also carry up to 120 kg (265 lb) of underwing bombs. The increased weight of the armament, spoiled flight characteristics, however, not enough to be rejected, so in June 1949 the Bulgarian Air Army ordered the mass production of the type.
The initial batches of the Laz-7.3 were still equipped with a fixed landing gear, but from the third production run onwards, the retractable landing gear was standardized. Some machines in the late production batches featured mechanical bomb release mechanisms, while others were equipped with pneumatic ones. Some very late models featured a different propeller, thanks to which higher altitudes could be attained.
A total of just 160 serial Laz-7 were manufactured between 1949 and 1950 and served through the 1950s with the Bulgarian Air Force School and some other flight clubs. Some night light bomber regiments equipped the type too, mimicking Soviet night bomber regiments, typically equipped with the Polikarpov Po-2.
The Laz-7.3 had every improvement the Laz-7.2 had and was equipped with a backwards retractable landing gear. When retracted, half of the wheel was left uncovered, feature which turned to be very useful in case of a belly landing. Unlike both Laz-7.1 and 7.2, where main pilot sat at the rear and the trainee at the front, in the Laz-7.3 the main pilot sat at the front, so he could have a better firing angle, as the Laz-7.3 was the first variant to be equipped with weapons. These consisted in two 7,7 mm M-30 machine guns mounted in the wings or one 7,92 mm T6-200 machine gun. It could also carry up to 120 kg (265 lb) of underwing bombs. The increased weight of the armament, spoiled flight characteristics, however, not enough to be rejected, so in June 1949 the Bulgarian Air Army ordered the mass production of the type.
The initial batches of the Laz-7.3 were still equipped with a fixed landing gear, but from the third production run onwards, the retractable landing gear was standardized. Some machines in the late production batches featured mechanical bomb release mechanisms, while others were equipped with pneumatic ones. Some very late models featured a different propeller, thanks to which higher altitudes could be attained.
A total of just 160 serial Laz-7 were manufactured between 1949 and 1950 and served through the 1950s with the Bulgarian Air Force School and some other flight clubs. Some night light bomber regiments equipped the type too, mimicking Soviet night bomber regiments, typically equipped with the Polikarpov Po-2.
Sources:
1st http://www.airwar.ru/enc/other/laz7m.html (translated)
2nd http://www.aeroflight.co.uk/waf/bulgaria/af/types/lazarov.htm
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