Yak-1 M-105PA winter variant, A.S.Yakovlev

General Information
Type Yak-1
Function Fighter (winter)
Year 1941
Crew 1
Powerplant
Type M-105PA
Power at 0m 1020hp
Takeoff Power 1100hp
Size
Length 8.48m
Height ?m
Wingspan 10.0m
Wing area 17.15m2
Weights and loads
Empty 2475kg
Loaded 2985kg
Wing Load (kg/m2) 174
Power load (kg/hp) 2.82
Speed
at 0m 441km/h
at 5100m 533km/h
Landing 144km/h
Maneuverability
Turn time 19.5sec
Roll
Landing 500m
Takeoff 360m
Range
Practical 550km
Ceiling
Ceiling 10400m
Climb
5000m 5.9min
Combat turn 900m
Payload
Fuel 305kg
Gun TypeAmmo
1*20mm ShVAK 120
2*7.62mm ShKAS 2*750
Salvo (kg/sec) 1.73
On some aircraft:
Bombs up to 2*100kg
or Rockets 6*RS-82
Yak-1 on skis
(75k) Yak-1 on skis from "Soviet Combat Aircraft of the Second World War" by Yefim Gordon and Dmitri Khazanov, Vol.1
Courtesy of Thomas Heinz

Yak-1 M-105PA was built in special variant during winter season 1941- 1942. Harsh conditions of Russian Winter are very demanding not only on troops, but on any type of equipment, and special measures are to be taken to keep aircraft in high combat readiness and allow to perform service in open field conditions. Foreseeing those problems already in Summer 1941, the GKO (August 14) ordered the NKAP to design, produce and present to the VVS universal (except the top side fairing) ski design suitable for LaGG-3, MiG-3 and Yak-1. All had to be done in two weeks timeframe.

Corresponding order from NKAP followed next day to A.S.Yakovlev for a good reason: Yakovlev's first prototype I-26-1 passed the factory trials on snow covered field, equipped with skis.

Main ski, designed at Yakovlev KB was of 2-spar design, 62x165cm2 size. Weight of a pair was 123kg. Tail ski was also retractable, same for all types of fighters. Weight - 6kg.

Yak-1 on skis
27k Yak-1 on skis from "Soviet Combat Aircraft of the Second World War" by Yefim Gordon and Dmitri Khazanov, Vol.1
Courtesy of Thomas Heinz

Winter variant of Yak-1 was a series production aircraft with changes to landing gear and powerplant, painted with winter camouflage. Analysis of those changes is presented below:

Landing Gear: wheels were replaced by retractable skis. Despite original fighter design was developed without such a conversion in ming, modification was performed without major airframe changes. Even the leg and retraction system remained unchanged. During retraction, skis were raised tight to the ex-wheels wells, proturbing 600mm in front of the wing leading edge. This part of the ski had special fairing, providing smooth match with the wing surface.

Positive resultsNegative results
  • Ski-fitted Yak-1 could operate from snow-covered fields without special cleaning or rolling the landing strip.
  • Lowered center of gravity (heavy skis!) made landing much easier and safer - Yak-1 trend to noseover was temporary cured.
  • Landing gear weight was increased by 50kg.
  • Skis themselves as well as the gaps between ski and wing created extra drag, decreasing aircraft speed by 20 to 30km/h.
  • Large traction increased takeoff run of the aircraft.
  • During continuous parking, snow sticks to the ski surface.
  • Ski undersurface lasted only for 70 to 80 takeoff/landing cycles.

    • Powerplant: oil and water system elements (tubes, tanks, filters) under the engine cowling were provided with heat-preserving wrapping. Special system was responsible for liquefying the oil using the gasoline. Water was replaced by antifreeze, capable to handle frigid winter temperatures. Aircraft was supplied to airforce with set of cotton-filled blankets and plugs ('pillows'), specially shaped to cower the propeller spinner, engine, radiators and air intakes.

    Positive resultsNegative results
  • Engine could be quickly started 'cold' under any temperature conditions;
  • Engine could stay warm for a long time without necessity to run it frequently;
    		•
  • 20kg of takeoff weight added;

    • Camouflage: Winter Variant of Yak-1 was painted with white glue-based washable paint right over the standard summer camouflage.

    Positive resultsNegative results
  • Parked aircraft became almost undetectable from the air.
    		•
  • 4 to 5kg of takeoff weight added;
  • Rough paint surface consumed 7 to 10km/h of speed. But some sanding of the surface allowed to reclaim this loss easily.

    • Flight technic of the ski-fitted Yak-1 did not differ from the standard aircraft. But combat use of ski-equipped fighters proved to be a failure. Luftwaffe operated their fighters on wheels all the year around, and speed losses of Soviet fighters did not compensate for some airfield advantages.

    Some 830 Yak-1's were fitted with ski landing gear in period from September 1941 to February 25, 1942, when the concept was finally disregarded. Since 1942 ski-fitted fighters saw only limited service with the North Front regiments.

    Rejection of the ski undercarriage put stricter demands on the airfield preparation and increased workload on the BAO. Special tools had to be developed and produced, but it was necessary to return combat performance to the combat planes.

    Yak-1 on takeoff skis
    40k b/w Yak-1 ready for 'takeoff-skis', "History of aircraft construction in the USSR", Vol.2 p.300

    Different concept surfaced later, when test-pilot of NII VVS B.K.Kondratiev proposed so called 'takeoff skis'. Those skis were not attached to the aircraft and did not help during landing. This solution found limited use only, mostly to transport damaged aircraft within airfield or from the scene of emergency landing.

    PredecessorsModifications
    series Yak-1 with M-105P
    Yak-1 M-105P/PA    		 None
    ReferencesLinks
  • "Yak fighters of the Great Patriotic War period" by A.T.Stepanets
    		•
  • Accurate Miniatures Yak-1 on Skis - not a historic thing, but very good for modellers
    • Created April 28, 2000 Back to
    Main Gate