I-185 M-71 etalon
First flight: June 1942
Delivery into squadron service: Never
Number built: 1
Power plant: Shvetsov M-71
Armament: Three synchronized 20 mm ShVAK cannons (total of 500 rounds)
Dimensions: Wingspan - 32' 13/4";
Length - 26' 5"
Wing area: 15.53 m2 (167.1 ft2)
Empty weight: 3,130 kg (6,900 lbs)
Loaded weight: 3,735 kg (8,234 lbs)
Top speed at sea level: 600 kph (372.8 mph)
Top speed at altitude: 680 kph (422.5 mph) at 6,100 m (20,013 ft)
Time to climb to 5,000 m (16,404 m): 4.7 minutes
Service Ceiling: 11,000 m (36,089 ft)
Virage Time: 22.5 seconds
History
Produced in April of 1942, the I-185 etalon (or 'standard settler') was the version of the Polikarpov I-185 that was designated to become the final production variant of the I-185. This I-185 underwent manufacturer's flight tests in June-October and was submitted for State acceptance trials at NII VVS on the 18th of November.
The aircraft weighed in at a total of 3,629 kg, 144 kg more than the the 1941 produced prototype of the I-185 M-71, but it differed from all the other I-185s in having the engine cowling's external and internal aerodynamics improved, resulting in a substantial reduction in drag.
The aircraft was found to be extremely maneuverable, and at the time of testing, surpassed all other Soviet and German designs in overall performance. However, the design was certainly not without its flaws.
From the 17th of December 1942 to the 26th of January 1943, testing on the aircraft was interrupted by the need to replace the M-71 engine, owing to frequent failures. Shortly afterwards, the new engine failed after less than 24 hours of running. On January 27th, the fighter crashed due to an in-flight engine failure. Then, on April 5th, the aircraft suffered another in-flight engine failure, and the prominent test pilot Vasiliy Stepanchonok was killed when when attempting a deadstick landing.
It was later decided to stop production of the I-185 because of its unreliable engine. like the aircraft's 1941 produced prototypes, this version of the I-185 never got to see use in service tests with the 728th
Sources:
Soviet Air Power in World War 2 - Yefim Gordon
https://forum.warthunder.com/index....5-m-71-etalon-39standard-settler39-in-detail/