Lavochkin-Gorbunov-Gudkov LaGG-3, part five. Prototypes and experimental variants

 

There were also some prototypes and experimental variants based on the LaGG-3. Those were the following:

• LaGG-3 M-107: In order to improve LaGG-3's performance and keep it under production Lavochkin fitted a Klimov M-107 engine rated at 1.300 hp at 5.000 m (16.400 ft) to a LaGG-3. Test flights were cut short due to an overheating problem and, as it gave no serious advantage over the LaGG-3 powered with the Klimov M-105P engine, it was discarded.
• Gudkov Gu-82: This was a single-engine low-wing fighter developed by Mihail I. Gudkov. It was initially a radial-powered variant of the LaGG-3 fighter.
  Lavochkin Gorbunov and Gudkov, who were the designers of the original LaGG-3, believed that almost all flaws of their fighter could be solved by fitting a new engine, the Shvetsov ASh-82 (AKA M-82) radial engine rated at 1.330 hp of power. This new engine developed more power than the Klimov M-105 in the LaGG-3, with the expense of a slightly higher frontal area. It had also the advantage that it could still work if one of the cylinders was shot out. 
  On 25th August 1941 Gudkov was allocated an engine and he began to set it up into a LaGG-3 together with additional firepower; namely two 12,7 mm (0.50 in) Berezin UB machine guns plus two 20 mm (0.787 in) ShVAK cannons. 
  The aircraft, with the official designation of Gu-82, flew successfully for the first time on 11th September 1942 and it was found that its maximum speed of 573 km/h (356 mph) was slightly higher than its predecessor and it was also more agile. Gudkov presented the results to the Commissariat of the People for Aviation Industry (NKAP) and pushed for mass producing the type. His pleads were received with enthusiasm by the pilots who were looking forward to have better fighter aircraft to fight off their German foes. However, Lavochkin had developed another variant of the LaGG-3 with a radial engine, the Lavochkin La-5, which proved to be much better and therefore the Gu-82 was cancelled.
• Gorbunov Gu-105: During May 1943 a new variant of the LaGG-3 designed by Gorbunov was designated as Gorbunov Gu-105. This variant introduced many new improvements and features such as better streamlining, lighter weight, cut down rear fuselage and a new canopy to improve rear vision. Emphasis was made in the type being streamlined while still powered by the Klimov M-105PF engine with data supplied from the Yakovlev Yak-1M. 
  This variant was lighter than the Series 66 of the LaGG-3 and was also significantly faster. It had also better rate of climb and maneuverability. In spite of not having wing slats, like the LaGG-3 had, the test pilot reported that the Gu-105 was superior to all Messerschmitt variants in terms of trouble free handling and maneuverability. 
  In February 1944 a second prototype powered by a Klimov M-105PF-2 rated at 1.300 hp, was completed. This, named as Gorbunov Gu-105-2 was armed with one 23 mm (0.905 in) VYa-23 cannon. 
  When tested in May and June 1944 the test pilot said that both in maximum speed and climb rate the Gu-105-2 was inferior to the Yakovlev Yak-1M tested by the NII (Scientific Research Institute) in October 1943. Furthermore, oil and water overheating problems meant that speed could only be sustained for during three or four minutes. 
  Despite having a more powerful engine, performance wasn't good enough and it was decided to concentrate production efforts on the Yakovlev Yak-3 and the Lavochkin La-5 instead. 

Sources:

1. https://en.wikipedia.org/wiki/Lavochkin-Gorbunov-Gudkov_LaGG-3
2. https://en.wikipedia.org/wiki/Gudkov_Gu-82
3. Signal Squadron - Aircraft In action 163 - LaGG Fighters in Action

4. https://massimotessitori.altervista.org/sovietwarplanes/pages/lagg3/lagg3.html

5. https://www.valka.cz/Lavockin-LaGG-3-t41330