|Year||1942||April 1942||Sept. 1942|
|Type||M-105 PA||M-105 PA modified||M-105 PF|
|Power at 0m (hp)||1020||?||1210|
|Power at altitude||see engine page|
|Weights and loads|
|Wing Load (kg/m2)||170||170||170|
|Power load (kg/hp)||2.78||?||2.43|
|at ()m||559 (4450)||? (?)||571 (3650)|
|Turn time (sec)||20.0||19.0||19.0|
|Rate at 0m (m/sec)||12.2||15.5||?|
|Bombs||See a story of the Yak-1 in fighter-bomber role|
In April 1942 an effort was made to boost the M-105PA engine in the field conditions. Joint brigade from Moscow Engine Plant and NII VVS (lead by military engineer B.K.Nikitin) modified seven aircraft of the 236thIAP (West Front, under command of P.A.Antonets). The air pressure (in carburetor?) was increased to 1050mm.Hg. Importantly, the engine could be modified by airfield technicians without interrupts in the combat operations.
Aircraft performance improved, and pilots flew modified planes with enthusiasm for some time. Perspective of effective low-cost modification appeared very bright, but...
More scrupulous analysis of modified powerplant revealed number of drawbacks. Even at normal Summer temperatures 18...23°C horizontal flight with full power was possible for only 2 to 3 minutes. After this oil and water temperatures exceeded allowed maximum. Engine also overheated during climb, and it was necessary to level aircraft every 2500 to 3000m. Overheating resulted in increased oil leaks. Oil spills contaminated radiator surface and the windshield, forcing the pilot to fly with open canopy (15km/h speed penalty).
When those controversial results reached VVS command, two modified Yak-1s were ferried to the NII VVS for systematic study. Full-scale flight evaluation program confirmed gains in performance, as well as the fact that overheating problems do not allow to utilize those advantages during desired time intervals. Based on trials result, the NKAP ordered the engine modifications together with cooling system changes to be introduced on the series Yaks.
Since May 1, 1942 M-105PA was replaced on production lines (Engine Factory N°26) by M-105PF with air pressure boosted to 1050mm.Hg and modified carburetor. This engine was soon renamed VK-105PF for its chief designer V.Klimov. On May 29 1942 GKO ordered production of Yak-1 with VK-105PF engine, and since June 4 all Yak-1s rolled out with new engine and OP-352 oil cooler with increased cooling surface.
First production Yak-1 with boosted engine passed trials at NII VVS in September 1942 by pilot V.I.Khomiakov. Comparison with standard M-105PA-powered Yak-1 satisfied all expectations. At the same time increased engine power 'sharpened' the tendency of Yak-1 to 'raise the tail' even during the engine testing. Ground crew had to hold the tail to prevent sudden noseover. Also aircraft became more demanding to careful wheel brakes use during landing and taxi.
|Created May 15, 2000||Back to|