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{{Short description|Soviet fighter aircraft designed in 1940}}
{{good article}}
{{Infobox aircraft
 | name=Polikarpov I-185
 | image=Polikarpov I-185 (M-71).jpg
 | caption=Side view of the I-185 with a M-71 engine
 | type=[[fighter aircraft|Fighter]]
 | national_origin=[[Soviet Union]]
 | manufacturer=[[Polikarpov]]
 | designer=
 | first_flight=11 January 1941
 | introduction=
 | retired=
 | status=Cancelled
 | primary_user=
 | number_built=4
 | developed_from=[[Polikarpov I-180]] 
 | variants=
}}
The '''Polikarpov I-185''' was a [[Soviet Union|Soviet]] [[fighter aircraft]] designed in 1940. It was flown with three engines but all of them were either insufficiently developed for service use or their full production was reserved for other fighters already in production. The I-185 program was cancelled on 27 January 1943. Engines used with the I-185 included the Shvetsov M-71, which was more prominent and the Shvetsov M-82, which was also used on [[Lavochkin La-5]] fighters. Only a few M-82 variants were produced.

==Design and development==
The I-185, designed in early [[1940 in aviation|1940]], was based on the [[Polikarpov I-180|I-180]], which was itself a development of the [[Polikarpov I-16|I-16]], but was virtually a new design. The [[monocoque]] fuselage was similarly built of 'shpon', molded birch plywood, and also had an integral fin, but it was considerably longer than that of the I-180. The two-[[spar (aviation)|spar]], all-metal wing was smaller and thinner than the I-180's wing, nearly as thin as that of the [[Supermarine Spitfire]]'s wing at 13% at the root and tapered to 8% at the wing tip.<ref>Gordon and Dexter, pp. 94–95</ref> The wing had a NACA-230 profile and was skinned in [[duralumin]]. Pneumatically powered split [[flap (aircraft)|flap]]s and [[leading edge slat]]s were fitted. The outer wing panels had 3° of [[dihedral (aircraft)|dihedral]]. The fabric-covered control surfaces were framed in duralumin. The protected {{convert|540|L|0|adj=on}} fuel tanks were mounted between the wing center section spars. The I-185 used a [[conventional undercarriage]] with a retractable tailwheel. The unproven 1,492&nbsp;kW (2,000&nbsp;hp) 18-cylinder, two-row [[Tumansky M-90]] [[radial engine]] was carried on welded steel tubes. It was fitted with a ducted spinner to improve cooling with the air expelled through gills as in the I-180 to provide additional thrust.<ref>Gunston, p. 308</ref> The synchronized armament was mounted in the fuselage: two {{convert|7.62|mm|abbr=on}} [[ShKAS machine gun]]s and two {{convert|12.7|mm|abbr=on}} [[Berezin UB]]S [[machine gun]]s. A {{convert|500|kg|adj=on}} bomb could be carried under overload conditions. The first prototype was completed in May 1940, but the only available example of the M-90 did not provide enough power for take-off. The prototype was modified to use another experimental engine, the {{convert|895|kW|adj=on}} [[Shvetsov M-81]] radial, but this was not nearly powerful enough for flight tests. The I-185 (M-81) finally took to the air on January 11, 1941, but it was decided not to waste further development and await a more powerful engine which was fortunate as the M-81 was cancelled in May 1941.<ref name=gd5>Gordon and Dexter, p. 95</ref>

A second prototype was completed at the end of 1940 with a 14-cylinder, 1,268&nbsp;kW (1,700&nbsp;hp) [[Shvetsov M-82]]A radial engine. The forward fuselage had to be redesigned to accommodate the slimmer engine and the armament was revised to three synchronized {{convert|20|mm|abbr=on}} [[ShVAK cannon]]. The drawings for this engine installation was passed to [[Lavochkin]] and [[Yakovlev]] where they proved very useful in designing their own fighters using the M-82 engine, notably the [[Lavochkin La-5]]. A third prototype was also built that used the larger and heavier [[Shvetsov M-71]] radial engine of 1,492&nbsp;kW (2,000&nbsp;hp). The flight tests of both of the latter versions were interrupted by the [[Operation Barbarossa|German invasion]] in June 1941 and all three prototypes, along with the entire [[Polikarpov]] design bureau, were evacuated to [[Novosibirsk]].<ref>Gordon and Dexter, pp. 95–96</ref>

Flight testing resumed in early 1942 and the M-71-powered versions, which now included the re-engined first prototype, proved to be faster than the [[Messerschmitt Bf 109]]F by {{convert|47|km/h|abbr=on}} at sea level and {{convert|20|km/h|abbr=on}} at {{convert|6000|m|0}} with a top speed of {{convert|630|km/h|abbr=on}} at that altitude.<ref>Gordon and Dexter, pp. 96, 100</ref> It was recommended for immediate production, even before it began combat trials in November 1942. All three aircraft were assigned to the 728th Fighter Aviation Regiment of the [[3rd Air Army]] of the [[Kalinin Front]] and were tightly controlled to prevent the loss of the prototypes. For example, all sorties had to be flown over Soviet-controlled territory and required the express permission of the 3rd Air Army staff to fly.<ref>Gordon and Dexter, p. 100</ref> Pilots' reports were quite enthusiastic; the 728th's commander, Captain Vasilyaka wrote: "The I-185 outclasses both Soviet and foreign aircraft in level speed. It performs aerobatic maneuvers easily, rapidly and vigorously. The I-185 is the best current fighter from the point of control simplicity, speed, maneuverability (especially in climb), armament and survivability."<ref>Gordon, p. 275</ref>

Based on the glowing report by the NII VVS (''Nauchno-Issledovatel'skiy Institut Voyenno-Vozdushnykh Sil''—Air Force Scientific Test Institute) in early 1942 preparations began to put the I-185 (M-71) into production. A 'production standard setter (etalon)' aircraft was built in April 1942 with a redesigned engine cowling. Its gross weight increased by {{convert|144|kg|abbr=on}} over the earlier prototypes, but the reduction in drag from the new cowling was significant and the top speed increased to {{convert|650|km/h|abbr=on}} at 5000 meters. It underwent manufacturer's tests between June and October and was submitted for the State acceptance tests on 18 November. However, flight testing was interrupted by the need to replace the engine between 17 December 1942 and 26 January 1943. The new engine failed the next day and the aircraft crashed on 27 January. Flight tests were ordered to be continued with the original prototypes to validate the range figures, but the first prototype crashed on 5 April, killing the pilot as he attempted a dead-stick landing.<ref>Gordon, pp. 275–76</ref>

Following a conversation between Yakovlev and Stalin where Yakovlev refuted the performance data, all work to put the I-185 into production was cancelled, even with the M-82 engine, as they were all required for the La-5 fighter. Another reason cited was that the La-5 used the fuselage of the [[Lavochkin-Gorbunov-Goudkov LaGG-3]] which was already in production in three plants and would involve less disruption of the production lines. Another factor may have been that the La-5 required less duralumin to build, something in short supply at the time.<ref>Gordon and Dexter, p. 101</ref>

==Variants==
Polikarpov began preliminary design of two updated versions of the I-185 design in February 1943. The I-187 had a M-71F engine of 1,640&nbsp;kW (2,200&nbsp;hp), a [[bubble canopy]], four 20&nbsp;mm cannons, eight [[RS-82 rocket]]s and an estimated maximum speed of 710&nbsp;km/h (441&nbsp;mph). The I-188 used an improved M-90 engine with 1,552&nbsp;kW (2,080&nbsp;hp) and used the same armament as the I-187, although the fuselage was slimmer than that of the I-187 because of the slimmer engine.<ref>Gordon, p. 277</ref>

==Specifications (I-185 (M-71 etalon))==
{{Aircraft specs
|ref={{citation needed|date=October 2019}}
|prime units?=met
<!--
        General characteristics
-->
|crew=1
|length m=7.77
|length note=
|span m=9.8
|span note=
|height m=2.5
|height note=
|wing area sqm=15.53
|wing area note=
|aspect ratio=<!-- sailplanes -->
|airfoil='''root:''' [[NACA airfoil|NACA 23014]]; '''tip:''' [[NACA airfoil|NACA 23008]]<ref name="Selig">{{cite web |last1=Lednicer |first1=David |title=The Incomplete Guide to Airfoil Usage |url=https://m-selig.ae.illinois.edu/ads/aircraft.html |website=m-selig.ae.illinois.edu |access-date=16 April 2019}}</ref>
|empty weight kg=2654
|empty weight note=
|gross weight kg=3500
|gross weight note=
|max takeoff weight kg=
|max takeoff weight note=
|fuel capacity=
|more general=
<!--
        Powerplant
-->
|eng1 number=1
|eng1 name=[[Shvetsov M-71]]
|eng1 type=18-cylinder air-cooled radial piston engine
|eng1 kw=1492
|eng1 note=

|prop blade number=3
|prop name=constant-speed propeller
|prop dia m=<!-- propeller aircraft -->
|prop dia note=
<!--
        Performance
-->
|max speed kmh=680
|max speed note=
|cruise speed kmh=
|cruise speed note=
|stall speed kmh=
|stall speed note=
|never exceed speed kmh=
|never exceed speed note=
|minimum control speed kmh=
|minimum control speed note=
|range km=835
|range note=
|combat range km=
|combat range note=
|ferry range km=
|ferry range note=
|endurance=<!-- if range unknown -->
|ceiling m=11000
|ceiling note=
|g limits=<!-- aerobatic -->
|roll rate=<!-- aerobatic -->
|climb rate ms=18.5
|climb rate note=
|time to altitude=
|wing loading kg/m2=
|wing loading note=
|disk loading kg/m2=
|disk loading note=
|fuel consumption kg/km=
|power/mass={{cvt|0.430|kW/kg}}
|more performance=<!--<br />
*'''Take-off run:''' {{cvt||m|0}}
*'''Take-off run to {{cvt|15|m|0}}:''' {{cvt||m|0}}
*'''Landing run:''' {{cvt||m|0}}
*'''Landing run from {{cvt|15|m|0}}:''' {{cvt||m|0}}-->
<!--
        Armament
-->
|guns=3 × 20 mm [[ShVAK]] cannon
|bombs=Up to 500 kg (1,100 lb) of bombs (2 × 250 kg (551 lb) or 4 × 100 kg (220 lb))
|rockets=  8 × [[RS-82 rocket]]s
|avionics=
}}

==See also==
{{aircontent|
|related=
*[[Polikarpov I-180]]
|similar aircraft=
*[[Yakovlev Yak-7]]
*[[Mikoyan-Gurevich I-210]]
*[[Bloch MB.155]]
*[[Focke-Wulf Fw 190]]
*[[Kawasaki Ki-60]]
*[[Macchi C.202 Folgore]]
*[[Nakajima Ki-44]]
*[[Reggiane Re.2002 Ariete]]
*[[Vultee P-66 Vanguard]]
*[[North American P-51 Mustang]]
*[[Grumman F6F Hellcat]]
*[[Hawker Typhoon]]
}}

==References==

===Notes===
{{Reflist|30em}}

===Bibliography===
{{commons category|Polikarpov I-185}}
* Abanshin, Michael E. and Gut, Nina. ''Fighting Polikarpov, Eagles of the East No. 2''. Lynnwood, WA: Aviation International, 1994. {{ISBN|1-884909-01-9}}.
* Gordon, Yefim and Dexter, Keith. ''Polikarpov's Biplane Fighters'' (Red Star, vol. 6). Earl Shilton, Leicester, UK: Midland Publishing, 2002. {{ISBN|1-85780-141-5}}
* Green, William and Swanborough, Gordon. ''The Complete Book of Fighters''. New York: Smithmark Publishers, 1994. {{ISBN|0-8317-3939-8}}.
* Gordon, Yefim. ''Soviet Airpower in World War 2''. Hinckley, England: Midland Publishing, 2008 {{ISBN|978-1-85780-304-4}}
* Guglya, Yu. A. and Ivanov, V.P. (Гугля, Ю.А., Иванов, В.П.) "Rokovoi I-180" ("Роковой И-180") ("The Fatal I-180") {{in lang|ru}}. ''Aerohobbi'' nr.1/94, 1994.
* [[Bill Gunston|Gunston, Bill]]. ''The Osprey Encyclopaedia of Russian Aircraft 1875–1995''. London, Osprey, 1995 {{ISBN|1-85532-405-9}}
* Kopenhagen, W. (ed.) ''Das große Flugzeug-Typenbuch''. Transpress, 1987. {{ISBN|3-344-00162-0}}.
* Léonard, Herbert. ''Les avions de chasse Polikarpov''. Rennes, France: Éditions Ouest-France, 1981. {{ISBN|2-85882-322-7}}. (French)
* Léonard, Herbert. ''Les chasseurs Polikarpov''. Clichy, France: Éditions Larivière, 2004. {{ISBN|2-914205-07-4}}. (French)
* Maslov, Mikhail (Маслов, Михаил). ''И-180 / И-185 (I-180/I-185)'' {{in lang|ru}}. Moscow: Tekhnika-molodezhi; Vostochnyi gorizont, 2003.

{{Polikarpov aircraft}}
{{WWIIUSSRAF}}

[[Category:1940s Soviet fighter aircraft]]
[[Category:Polikarpov aircraft|I-185]]
[[Category:Single-engined tractor aircraft]]
[[Category:Aircraft first flown in 1941]]