View source for Polikarpov I-180

{{Short description|Soviet aircraft prototype}}
{{Infobox aircraft
  |name =  I-180
  |image =I-180.jpg
  |caption = I-180-3 prototype
  |type = Fighter
  |manufacturer = [[Polikarpov]]
  |designer = [[Nikolai Nikolaevich Polikarpov]]
  |first_flight = 15 December 1938
  |introduction =
  |retired =
  |status = Cancelled
  |primary_user = [[Soviet Air Forces]]
  |more_users =
  |produced = 1938–1940
  |number_built = 10 production + 3 prototypes
  |unit cost =
  |developed_from = [[Polikarpov I-16]]
  |variants =
  |developed_into=[[Polikarpov I-185]]
}}

The '''Polikarpov I-180''' ({{langx|ru|И-180}}) was a 1938 [[Soviet Union|Soviet]] [[fighter aircraft|fighter]] prototype. It was the last attempt to extract performance from the basic [[Polikarpov I-16]] design.<ref name= "Green">Green 1973, p. 165.</ref> The development cycle was plagued with problems,<ref>Abanshin and Gut 1994, p. 52.</ref><ref>Gordon and Khazanov 1998, p. 111.</ref> especially with the death of the star Soviet test pilot [[Valery Chkalov]] in one of the prototypes.

==Design and development==
The I-180 represented a further development of the basic [[Polikarpov I-16|I-16]] design in order to take advantage of the new [[radial engine]]s coming into service. It was designed to meet a requirement of the [[Soviet Air Force]] of January 1938 for a new [[interceptor aircraft]] with a radial engine. It was preceded by a series of projected I-16 variants with a more powerful [[Tumansky M-88]] two-row radial engine: I-161, I-162, I-163, I-164, I-165, I-166 and I-167.

The I-180 was a single-engine, low-wing monoplane aircraft of mixed construction with a [[duraluminum]] frame covered in [[plywood]] and fabric. The pilot sat near the tailfin in an open cockpit with a windshield similar to the I-16. The landing gear was retracted pneumatically, including the tail wheel. The main visual difference between the I-180 and I-16 was a new wing with a perpendicular straight leading edge, and an aerodynamically refined fuselage with a longer slim engine [[cowling]].<ref name= "Green"/> The new fighter was to be powered by an 820&nbsp;kW (1,100&nbsp;hp) M-88 engine, a development of the license-built [[Gnome-Rhône Mistral Major]] (known as M-85 in the [[USSR]]), and represented the next step in evolution from the 1937 I-165-11 prototype. The proposed armament consisted of four 7.62&nbsp;mm (0.3&nbsp;in) [[ShKAS machine gun]]s and 200&nbsp;kg (440&nbsp;lb) of bombs. [[Dmitri Lyudvigovich Tomashevich|Dmitriy Tomashevich]] was assigned as the lead designer.

The ill-fated development of the I-180 started early on. The only version of the M-88 available at the time used reduction gear requiring a very large propeller, at least {{convert|3.2|m|ftin|sp=us}} in diameter – massive for an aircraft that in layout and dimensions resembled an I-16 with an elongated nose. Even before leaving the drawing board, the fighter had to be redesigned for an M-88R engine with reduction gear and a [[constant-speed propeller]]. The projected top speed fell from 572&nbsp;km/h (355&nbsp;mph) to 557&nbsp;km/h (345&nbsp;mph). The first prototype, however, was eventually fitted with a similar M-87 950&nbsp;hp engine, because the M-88R was not ready.<ref name=maslov>Maslov 2003</ref> The prototype was built at Number 156 Factory in Moscow.

==Testing and evaluation==
The VISh-23Ye propeller was delayed, and early test runs were conducted using a different propeller with manual pitch control (VISh-3Ye). Consequently, the engine was prone to overheating, and to compensate for this the cowling flaps restricting airflow around the engine were removed. Despite these problems, and the fact that the prototype had not completed all ground tests, the authorities were demanding a test flight as soon as possible. Polikarpov himself objected to flying the prototype before it would be ready, around February 1939, but he could not stop it. The series of events which took place on 15 December 1938, while not entirely clear, are tragic. Neither Polikarpov nor Tomashevich approved the initial flight, and no one had signed the form releasing the prototype from the factory. The famous Soviet test pilot [[Valery Chkalov]] took off and made a low-altitude circuit around the airfield. For the second circuit, Chkalov flew farther away, climbing to over 2,000 m (6,560&nbsp;ft), even though the flight plan specifically forbade exceeding 600 m (1,970&nbsp;ft). Chkalov apparently miscalculated his landing approach and came in short of the airfield but, when he attempted to correct, the engine stalled. The pilot was able to avoid several buildings but crashed into a power line. Chkalov was thrown from the cockpit, badly injured, and died two hours later.

The official government investigation concluded that the engine stalled because it became too cold in the absence of the cowl flaps. Others hypothesized that Chkalov rapidly advanced the throttle and flooded the engine. As the result of the crash, Tomashevich and several other officials, including Arms Industry Department director S. Belyakin, who urged the first flight, were immediately arrested. Years later, fellow test pilot [[Mikhail Gromov (aviator)|M.M. Gromov]] blamed the designers for flawed engine cooling and Chkalov himself for deviating from the flight plan. Chkalov's son also claimed that a plot to assassinate his father had been brewing in the months preceding his death, but the circumstances of the crash make foul play unlikely. Regardless, with Chkalov's death Polikarpov's reputation with [[Joseph Stalin]] suffered a blow from which he would never recover.

Nevertheless, work on the I-180 continued. The second prototype '''I-180-2''' with a bigger wingspan of 10.09 m (33&nbsp;ft 1 in) and M-87A engine flew on 27 April 1939,<ref name=maslov/> and participated in the [[May Day]] parade a few days later. Later, the engine was changed to the M-87B and the wing construction was strengthened. The prototype demonstrated a top speed of 540&nbsp;km/h (335&nbsp;mph) and was recommended for mass production with the M-88 engine. Then, on 5 September 1939, I-180-2 piloted by [[Tomas Suzi]] crashed during high-altitude testing, killing the pilot. Again, the exact circumstances of the crash were unclear. According to eyewitnesses, the aircraft dove steeply (others claimed it fell in a spin) to 3,000 m (9,840 ft) where it leveled out, then entered a spin again, leveling out once more at 300&nbsp;m (985&nbsp;ft). The pilot then abandoned the aircraft but did not use his parachute. No definite explanation was ever given but hypotheses include blinding of the pilot by oil from a leaking oil cooler, a heart attack, or loss of consciousness due to the failure of oxygen equipment.

Preparations were carried out in 1940 to produce the first batch of 10 aircraft at Factory No.21 in [[Nizhny Novgorod|Gorki]], engaged in manufacturing the I-16. However, their production was extremely slow, without much attention of the aviation authorities, with the first 10 aircraft taking more than eight months. One of the reasons for this was that the local [[OKB]] led by [[M.M. Pashinin]] was designing their own I-16 based fighter, the [[Pashinin I-21]] and factory management had devoted all of their resources to the hometown favorite, with only six brand new engineers assigned to production of the I-180.{{Citation needed|date=May 2008}} While this was being investigated, the third prototype '''I-180-3''', powered by a more powerful M-88R engine and fitted with a stressed skin wing (replacing the I-16 type wing structure of the previous prototypes) was completed, flying on 10 February 1940.<ref name="Gunston Russian p307">Gunston 1995, p. 307.</ref> It was armed with two 12.7&nbsp;mm [[Berezin BS]]
and two 7.62&nbsp;mm [[ShKAS]] machine guns on a common gunbed over the engine.

<!-- Deleted image removed: [[File:I-180S crash.jpg|thumb|left|The second Polikarpov I-180S (production series) crashed at [[Khodynka Aerodrome]] on 26 May 1940]] -->
Finally in April 1940, three aircraft designated '''I-180S''' were completed, these being similar to the I-180-3, but reverting to an open cockpit and the I-16 type wing structure.<ref name="Gunston Russian p308">Gunston 1995, p. 308.</ref> Their test flights were favorable. The new fighter resembled I-16 in agility but was more stable. Top speed was 575&nbsp;km/h (357&nbsp;mph). Major criticisms included the open canopy and poor build quality. It was believed that fixing these defects would raise the top speed to 600&nbsp;km/h (373&nbsp;mph). However, the I-180-3 prototype crashed on 6 July 1940, when it entered an inverted spin due to pilot error.<ref name=maslov/> The pilot was able to safely bail out. In preparation for production, Polikarpov produced the definitive '''I-180-5''' with several modifications and '''M-88A''' engine without reduction gear. The aircraft could also accept the new '''M-89''' engine with 1,007&nbsp;kW (1,350&nbsp;hp) (up to 1,165&nbsp;kW (1,560&nbsp;hp) with fuel injection) which would raise its top speed to over 650&nbsp;km/h (404&nbsp;mph). There was also a proposal for the '''I-180Sh''' with improved main landing gear.

Then, near the end of 1940, Polikarpov was suddenly informed that the I-180 was being cancelled, and that Factory no.21 would manufacture [[LaGG-3]] fighters instead. The reason for this was a misconception of the Ministry of Aviation Industry, that radial engines in [[NACA cowling]]s were poorly suited for aircraft with top speeds of over 500&nbsp;km/h (310&nbsp;mph), owing to high drag. Former government officials later admitted that the fascination with liquid-cooled engines stemmed in part from attempts to imitate the then state-of-the-art [[Messerschmitt Bf 109]]. Stalin's dislike for Polikarpov after Chkalov's death probably also played a role.

According to some recent historians, such as Mikhail Maslov, the cancellation of the I-180 was caused by personal and non content-related reasons and might be considered an error.<ref name=maslov/><ref>Guglya and Ivanov</ref> Especially after Chkalov's death, the Soviet authorities started to promote young designers, in preference to Polikarpov, despite the fact that the I-180 was the best performing Soviet fighter at the time of its cancellation and that it was faster than the Bf 109. One prototype series I-180 developed a speed of 585&nbsp;km/h that could be improved after projected changes, such as adding a closed canopy. The next best fighter, Yakovlev's '''I-26''' ([[Yak-1]] prototype), suffered from a troublesome and protracted development cycle, but [[Alexander Sergeyevich Yakovlev]] was one of Stalin's favorites, which most probably saved his design. In addition, the I-180 could have been available much earlier than the Yak-1 and LaGG-3 types, and producing it with a temporary M-87 engine, until the M-88 could be improved, was a possibility. Crashes of I-180 prototypes were mostly accidental, and should not be regarded as disqualifying the design. Moreover, the I-180 showed much fewer "teething problems" than its counterparts, especially the Yak-1, confirming Polikarpov's competence in aircraft design. Another advantage was that the construction of the I-180 was similar to the I-16, which was familiar to the Soviet industry and pilots, but handling of the I-180 was even easier and it was more stable.<ref name=maslov/> The same situation recurred with Polikarpov's next design, the advanced [[Polikarpov I-185|I-185]], based on the I-180 design.

==Operators==
==={{USSR}}===
* [[Soviet Air Force]]

==Specifications (I-180S)==
{{Aircraft specs
|ref=Fighting Polikarpov, Eagles of the East No.2<ref>Abanshin and Gut 1994</ref>
|prime units?=met
<!--
        General characteristics
-->
|crew=1
|length m=7
|length note=
|span m=10.09
|span note=
|height m=2.45
|height note=
|wing area sqm=16.11
|wing area note=
|aspect ratio=<!-- sailplanes -->
|airfoil= [[Clark YH]]<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=1815
|empty weight note=
|gross weight kg=2429
|gross weight note=
|max takeoff weight kg=2650
|max takeoff weight note=
|fuel capacity=
|more general=
<!--
        Powerplant
-->
|eng1 number=1
|eng1 name=[[Tumansky M-88R]]
|eng1 type=14-cylinder twin-row air-cooled radial piston engine
|eng1 kw=820
|eng1 note=
|prop blade number=3
|prop name=constant-speed propeller
|prop dia m=<!-- propeller aircraft -->
|prop dia note=
<!--
        Performance
-->
|max speed kmh=585
|max speed note=at altitude
|cruise speed kmh=
|cruise speed note=
|stall speed kmh=
|stall speed note=
|never exceed speed kmh=
|never exceed speed note=
|range km=900
|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=16.7
|climb rate note=
|time to altitude=
|wing loading kg/m2=151
|wing loading note=
|fuel consumption kg/km=
|power/mass={{cvt|0.34|kW/kg}}
|more performance=<!--
* '''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=<br>
:* 2 × 12.7mm [[Berezin BS]] machine guns
:* 2 × 7.62mm [[ShKAS machine gun]]s
|bombs=<br>
:* 200 kg (440 lb) of bombs
}}

==See also==
{{aircontent|
|related=
* [[Polikarpov I-185]]
|similar aircraft=
* [[Bloch MB.152]]
* [[Fiat G.50]]
* [[Focke-Wulf Fw 190]]
* [[IAR 80]]
* [[Lavochkin LaGG-3]]
* [[Macchi C.200]]
* [[MÁVAG Héja]]
* [[Messerschmitt Bf 109]]E
* [[Mitsubishi A6M]]
* [[PZL.50]]
* [[Weiss Manfréd WM-23 Ezüst Nyíl]]
* [[Yakovlev Yak-1]]
|lists=
* [[List of military aircraft of the Soviet Union and the CIS]]
* [[List of fighter aircraft]]
|see also=
}}

==References==

===Notes===
{{Reflist}}

===Bibliography===
* Abanshin, Michael E. and Nina Gut. ''Fighting Polikarpov, Eagles of the East No. 2''. Lynnwood, WA: Aviation International, 1994. {{ISBN|1-884909-01-9}}.
* Gordon, Yefim and Dmitri Khazanov. ''Soviet Combat Aircraft of the Second World War, Volume One: Single-Engined Fighters''. Earl Shilton, Leicester, UK: Midland Publishing, 1998. {{ISBN|1-85780-083-4}}.
* Gordon, Yefim and Keith Dexter. ''Polikarpov's I-16 Fighter: Its Forerunners and Progeny (Red Star, vol.3)''. Earl Shilton, Leicester, UK: Midland Publishing, 2002. {{ISBN|1-85780-131-8}}.
* Green, William. ''Warplanes of the Second World War, Volume Three: Fighters''. London: Macdonald & Co. (Publishers), 1961. {{ISBN|0-356-01447-9}}.
* Green, William and Gordon Swanborough. ''WW2 Aircraft Fact Files: Soviet Air Force Fighters, Part 2''. London: Macdonald and Jane's Publishers, 1978. {{ISBN|0-354-01088-3}}.
* Guglya, Yu.A. and V.P. Ivanov (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 Encyclopedia of Russian Aircraft 1975–1995''. London: Osprey, 1995. {{ISBN|1-85532-405-9}}.
* Kopenhagen, W., ed. ''Das große Flugzeug-Typenbuch'' (in German). Stuttgart, Germany: Transpress, 1987. {{ISBN|3-344-00162-0}}.
* Léonard, Herbert. ''Les avions de chasse Polikarpov'' (in French). Rennes, France: Editions Ouest-France, 1981. {{ISBN|2-85882-322-7}}.
* Léonard, Herbert. ''Les chasseurs Polikarpov'' (in French). Clichy, France: Éditions Larivière, 2004. {{ISBN|2-914205-07-4}}.
* Maslov, Mikhail (Маслов, Михаил). ''И-180 / И-185 (I-180/I-185)'' {{in lang|ru}}. Moscow: Tekhnika-molodezhi; Vostochnyi gorizont, 2003.

==External links==
{{commons category|Polikarpov I-180}}
* [http://www.airwar.ru/enc/fww2/i180.html Photos and drawings] {{in lang|ru}}

{{Polikarpov aircraft}}
{{WWIIUSSRAF}}

[[Category:1930s Soviet fighter aircraft]]
[[Category:Polikarpov aircraft|I-180]]
[[Category:Single-engined tractor aircraft]]
[[Category:Low-wing aircraft]]
[[Category:Aircraft first flown in 1938]]
[[Category:Aircraft with retractable conventional landing gear]]
[[Category:Single-engined piston aircraft]]