Editing Polikarpov I-16 (section)

==Operational history==
Initial service experience revealed that the [[ShKAS machine gun]]s had a tendency to jam. This was the result of the guns being installed in the wings upside-down to facilitate the fit. The problem was addressed in later modifications. Evaluations from pilots confirmed the experience with prototypes. Controls were light and very sensitive, abrupt maneuvers resulted in spins, and spin behavior was excellent.  An aileron roll could be performed in under 1.5 seconds (roll rate over 240&nbsp;degrees/second).  The machine guns were fired via a cable and the required effort, coupled with sensitive controls, made precision aiming difficult.  The rear weight bias made the I-16 easy to handle on unprepared airfields because the aircraft was rather unlikely to flip over the nose even if the front wheels dug in.

The I-16 was a difficult fighter to fly.  The pilots had poor visibility,<ref name="Jackson p. 148">Jackson 2003 p. 148.</ref> the canopy tended to become fouled with engine oil, and the moving portion was prone to slamming shut during hard maneuvers, which caused many pilots to fix it in the open position.  The front section of the fuselage, with the engine, was too close to the [[centre of gravity]], and the pilot's [[cockpit]] too far to the rear. The Polikarpov had insufficient longitudinal stability and it was impossible to fly the aircraft "hands off".<ref name="Jackson p. 147">Jackson 2003, p. 147.</ref>

[[File:Polikarpov I-16-Mosca.jpg|thumb|I-16 in Spanish Republican colors with "[[Popeye]] mascot"]]

===Spanish Civil War===
At the start of the [[Spanish Civil War]] in 1936, Republican forces pleaded for fighter aircraft. After receiving payment in gold, [[Joseph Stalin]] dispatched around 475<ref name = "Gunston p. 85">Gunston 2003, p. 85.</ref> I-16 Type 5s and Type 6s. The first I-16s appeared in Spanish skies in November 1936.<ref name= "Maslov p.25">Maslov 2010, p. 25.</ref> The Polikarpov monoplanes had their baptism of fire on 13 November 1936, when twelve I-16s intercepted a Nationalist bombing raid on Madrid. Soviet pilots claimed four air victories and two German [[Heinkel He 51]] pilots were killed.  But the Soviets suffered losses too; the group commander collided with an enemy aircraft and another I-16 pilot crash landed.<ref name="Maslov p.26">Maslov 2010, p. 26.</ref> The Polikarpovs immediately began dominating the enemy Heinkel He 51 and [[Arado Ar 68]] biplanes{{Citation needed |date=September 2011}} and remained unchallenged until the introduction of the [[Messerschmitt Bf 109]].  The arrival of the newest Bf 109Bs and the overwhelming numerical superiority of Nationalist fighters were the primary cause of the heavy I-15 and I-16 combat losses suffered throughout 1937.<ref name = "Maslov p.30">Maslov 2010, p. 30.</ref> A number of aviation publications called the new Soviet fighter a "Boeing" due to the incorrect assumption that it was based on the [[Boeing P-26]]'s design.  The Nationalists nicknamed the stubby fighter ''Rata'' (Rat), while the Republicans affectionately called it ''Mosca'' (Fly).

Combat experience showed that the I-16 had deficiencies; several aircraft were lost after structural failure of the wings, which was quickly remedied by reinforced structures. Heavy machine gun bullets could sometimes penetrate the armored backrest, and fuel tanks occasionally caught fire in spite of being protected. The hot Spanish summers required the addition of oil radiators, and dust adversely affected the life of the engines. Although some aircraft accumulated up to 400 hours of flying time, the average life of an I-16 was 87 days, of which one sixth was spent on maintenance. The biggest complaint in service was the light armament of only two 7.62&nbsp;mm (0.30&nbsp;in) [[machine gun]]s. This was urgently addressed with the '''Type 6''' which added a third ShKAS in the bottom of the fuselage. The four-gun '''Type 10''' was nicknamed "Super Mosca" or simply "Super".
The total number of I-16s delivered to Spain from 1936 to 1938 amounted to 276. When the war ended on 1 April 1939, 187 ''Ratas'' had been lost in Spain: 112 lost in combat, one shot down by anti-aircraft fire, eleven destroyed on the ground, one force-landed and 62 lost in accidents.<ref name="Maslov p.32">Maslov 2010, p. 32.</ref>

===China, the Far East, and battles at Khalkhin Gol===
[[File:Soviet volunteer.jpg|thumb|I-16 Type 5 with Chinese insignia, flown by Chinese pilots and Soviet volunteers]]
Between October 1937 and September 1939 the USSR delivered 885 aircraft (rising to 1,250 by 1941), including 216 Polikarpov I-16s, predominately '''Type 5s and Type 10s'''. At first the Soviet pilots would have to fly the aircraft over 1,500 miles across China to get them to their destination of [[Lanzhou]], however this was a risky journey and so future batches of aircraft would be disassembled and transported to Hami (closer to Lanzhou), before final assembly and delivery to Lanzhou. The first I-16s were delivered in November 1937, however rushed training of the Chinese pilots meant many were lost to crashes. In Chinese service the I-16 became known as the "Lastochka" or "Swallow". In the early years of the war the I-16 was a capable fighter, however from 1939 onwards its performance was deemed to be lacking in comparison to newer fighters.<ref>{{Cite web |last=osprey.com |title=Polikarpov I-15, I-16 and I-153 Aces |url=https://www.ospreypublishing.com/ca/polikarpov-i15-i16-and-i153-aces-9781846039829/ |access-date=2024-06-17 |website=Osprey Publishing |language=en}}</ref><ref>{{Cite web |title=Major General Liu Chi-Sheng |url=http://www.century-of-flight.freeola.com/Aviation%20history/WW2/aces/Liu%20Chi-Sheng.htm |access-date=2024-06-17 |website=www.century-of-flight.freeola.com}}</ref>

A number Chinese aces flew the I-16; among them Lo Ying-Teh who in 1938 shot down Japanese unit leader Lt Ryohei Ushioda's A5M2 in his I-16 Type 5. .Another ace to fly the I-16 was Liu Chi-Sheng who achieved 3 of his 10 kills while flying the I-16 Type 5, along with another shared kill.<ref>{{Cite book |last=Cheung |first=Raymond |url=https://books.google.com/books?id=y4uHCwAAQBAJ |title=Aces of the Republic of China Air Force |date=2015-05-20 |publisher=Bloomsbury Publishing |isbn=978-1-4728-0563-8 |language=en}}</ref>

Another 250 '''I-16 Type 10s''' were supplied to China. This model added a second set of 7.62&nbsp;mm (0.30&nbsp;in) [[ShKAS machine gun|ShKAS]] machine guns, armor behind the pilot, and had a slightly upgraded 560&nbsp;kW (750&nbsp;hp) M-25 engine. In 1939, of the 500 I-16s<ref>Kotelnikov p. 109</ref> deployed to the fighting at [[Nomonhan]], approximately 112 were lost during the [[battles of Khalkhin Gol]], of which 88 were destroyed in aerial combat, primarily against the all-metal [[Nakajima Ki-27]] Japanese fighters.<ref>Nedialkov 2011, p. 141.</ref> During test trials in Russia of a captured Ki-27, the aircraft proved superior to the Soviet I-152 (I-15bis), [[I-153]], and the I-16 in aerial combat, as well as having a faster take-off and lower landing speed, requiring shorter airstrips than the I-16, which needed 270 meters to stop and 380 meters for take-off.<ref>Nedialkov p. 24, 25, 148</ref>

Further attempts were made to upgrade the firepower of the aircraft using 20&nbsp;mm (0.79&nbsp;in) [[ShVAK cannon]]s, making the I-16 one of the most heavily armed fighters of the period,<ref>Price 1975, p. 78.</ref> able to fire 28 rounds of ammunition in three seconds. Pilots loved the results, but the cannons were in short supply, and only a small number of the '''I-16 Type 12''', '''17''', '''27,''' and '''28''' were built. The Chung 28 is an unlicensed I-16 built from the spare parts of I-16s provided to the Nationalists, delivered in 1941 and did not include upgraded cannons. The cannons adversely affected performance, with 360° turn time increasing from fifteen seconds in the Type 5 to eighteen seconds. The '''Type 24''' replaced the skid with a tailwheel and featured the much more powerful 670&nbsp;kW (900&nbsp;hp) [[Shvetsov M-63]] engine. The '''Type 29''' replaced two of the ShKAS guns with a single 12.7&nbsp;mm (.50&nbsp;in) [[Berezin UB|UBS]]. Ten '''Type 17''' fighters were supplied to the [[Republic of China Air Force|Chinese Air Force]] where on 20 May 1940, they effectively shot down a [[Mitsubishi Ki-15|C5M scout-attack]] plane and three [[Mitsubishi G3M|G3M]] bombers during the [[Bombing of Chongqing|Battle of Chongqing]].<ref>{{Cite web|last=红岩春秋|first=唐学锋|date=2019-01-17|title=当年设施简陋的梁山机场, 没想到却是中国空军保卫重庆的第一道空中防线! - 上游新闻·汇聚向上的力量|url=https://www.cqcb.com/wenshi2/hongyanchunqiu/2019-01-17/1386817.html|archive-url=|archive-date=|access-date=2021-01-15|website=www.cqcb.com|quote="5•20"梁山空战, 我空军击落日机7架, 这是当时新闻媒体报道的数字, 难免有些夸大.根据南京的中国第二历史档案馆保存的《空军战斗要报》记载: 此役, 我空军一共击落敌轰炸机3架、侦察机1架.其大致情况如下: 1、第24队队长李文庠, 分队长张光蕴、王文骅、队员彭均、李廷凯等5员, 在梁山上空合力击落敌重轰炸机1架(残骸在寻觅中).2、队员陈少成在忠县上空击落敌侦察机1架, 该敌机在忠县汝溪焚毁, 番号为258, 敌乘员3人全毙.3、队员伍国培在梁山上空击落敌重轰炸机1架, 该机在忠县马家祠损毁, 番号为4528, 敌乘员6人全毙.4、分队长韩参在开县击落敌重轰炸机1架, 敌机残骸正寻觅中.从当天中国空军的战斗要报记载来看, 被击落的4架日机, 只有两架是查明了具体坠落的地点, 并找到了残骸, 而另外两架的残骸还在"寻觅"中.}}</ref><ref>Cheung, 2015, pp. 67-68. The 24th PS/4th PG received a small number of the ShVAK 20mm cannon-armed I-16 Type 17 fighters from the Soviets, and were used to good effect intercepting 24 G3Ms and a Ki-15 (C5M) on 20 May 1940</ref>

Types 18, 24, 27, 28, and 29 could be fitted to carry [[RS-82]] unguided rockets. The first successful use of air-to-air missiles in air combat was on August 20, 1939. A Ki-27 was hit by an RS-82 rocket launched from a distance of about a kilometer. The shot was fired by Captain N. Zvonarev.<ref>{{Cite book |url=https://books.google.com/books?id=zVEjAAAAMAAJ&pg=RA1-PA30 |title=NASA Technical Translation |date=1959 |publisher=National Aeronautics and Space Administration |language=en}}</ref>

A 1939 government study found the I-16 had exhausted its performance potential. The addition of armor, radio, battery, and flaps during the aircraft's evolution exacerbated the rear weight distribution problems to the point where the aircraft required considerable forward pressure on the stick to maintain level flight and at the same time developed a tendency to enter uncontrolled dives. Extension and retraction of the landing flaps caused a dramatic change in the aircraft's attitude. Accurate gunfire was difficult.

===Soviet Union===
[[File:Khalkhin Gol Soviet pilots august 1939.jpg|thumb|[[Soviet Air Force|VVS]] pilots at [[Khalkhyn Gol]] in front of their I-16 in August 1939.]]
The pilots nicknamed the aircraft ''Ishak'' (Russian: ''Ишак'', ''Donkey''/''[[Hinny]]'') because it was similar to the Russian pronunciation of "I-16" ("ee-shestnadtset"). When [[Operation Barbarossa]] erupted on 22 June 1941, 1,635 of 4,226 [[Soviet Air Force|VVS]] aircraft were I-16s of all variants, fielded by 57 fighter regiments in frontier areas.<ref name="Maslov p.68">Maslov 2010, p. 68.</ref> The main assault delivered by the Luftwaffe's ''Luftflotte'' 2 (in support of [[Wehrmacht]] Army Group Centre) was directed against the Soviet Western Special Military District, that deployed 361 (424 according to other sources) I-16s.<ref name="Maslov pp.68-69">Maslov 2010, pp. 68–69.</ref> During the early phase of the campaign the I-16 bases were the main targets for the German aircraft and after 48 hours of combat, of the 1,635 Polikarpov monoplanes in service on 21 June 1941, only 937 were left.<ref name ="Maslov p.69">Maslov 2010, p. 69.</ref> By 30 June the number of I-16s in western front line units had dropped to 873, including 99 that required repairs.<ref name="Maslov p.72">Maslov 2010, p. 72.</ref> To stem the Luftwaffe aerial assault several I-16 pilots adopted the ''[[Aerial ramming|taran]]'' tactic and sacrificed their lives, ramming German aircraft.<ref name="Maslov p.72" />

Its main opponent in the sky in 1941 was the German [[Messerschmitt Bf 109]].<ref name="Drabkin p.142">Drabkin 2007, p. 142.</ref> The I-16 was slightly more maneuverable than the early Bf 109s and could fight the Messerschmitt Bf 109E, or ''Emil'', on equal terms in turns. Skilled Soviet pilots took advantage of the Polikarpov's superior horizontal [[maneuverability]] and liked it enough to resist the switch to more modern fighters. The German aircraft, however, outclassed its Soviet opponent in service ceiling, rate of climb, acceleration and, crucially, in horizontal and diving speed, due to better aerodynamics and a more powerful engine. The main versions of the I-16 had a maximum speed of 450–470&nbsp;km/h (279–291&nbsp;mph), while the Bf 109E had a maximum speed of 560–570&nbsp;km/h (347–353&nbsp;mph), the more streamlined Bf 109F ''Friedrich'' could hit 615–630&nbsp;km/h (372-390plus&nbsp;mph). So German pilots held the initiative and could decide if they wanted to chase their opponents, could attack them from above and behind and then gain altitude for a new attack. Meanwhile, Polikarpovs could only defend each other by forming a defensive circle or via horizontal maneuverability.<ref name="Drabkin p.142" />

Moreover, in terms of armament, Messerschmitts had a slight edge on the I-16. The ''Emil'' carried two wing-mounted 20mm [[MG FF]] cannons and two synchronized 7.92&nbsp;mm [[MG 17 machine gun|MG-17s]] with a weight of a one-second [[salvo]] of 2.37&nbsp;kg, while the most common version of the I-16—armed with just two synchronized and two wing-mounted 7.62 ShKAS—could deliver 1.43&nbsp;kg of bullets each second.<ref name = "Drabkin pp.142-143">Drabkin 2007, pp. 142–43.</ref> Finally, the ammunition storage on a Messerschmitt exceeded that of the I-16, carrying 1,000 rounds for each machine gun (plus sixty [[Drum magazine|drum]]-housed rounds for each cannon), while the Polikarpov carried just 450 rounds for each ShKAS gun.<ref name="Drabkin p.143">Drabkin 2007, p. 143.</ref>

Around half of all produced I-16s were still in service in 1943, when they were finally replaced.{{Citation needed|date=May 2020}}

Specially modified I-16s were used in the [[Zveno project|Zveno]] [[parasite aircraft]] experiments using the [[Tupolev TB-3]] as a mothership. These I-16s carried two 250&nbsp;kg bombs for dive bombing. This was more than double the bomb load an I-16 could take off with under its own power. Once the bombs were dropped, they could perform as normal I-16s, and could re-attach to the TB-3 for the return journey.<ref name="Shavrov 1985"/>

The [[Luftwaffe]] was known to have captured some I-16 and UTI-4 two-seat trainers (two of which were marked with the ''Stammkennzeichen'' codes DM+HC and DM+HD) and flown from the [[Rechlin-Lärz Airfield|''Erprobungstelle Rechlin'']] central Luftwaffe test facility by [[Kampfgeschwader 200]] (KG 200).<ref>Thomas 2004, p. 80.</ref> The Luftwaffe was not the only air force able to test its fighters against the I-16; the Japanese captured a few I-16s as well,<ref name="Liss 1966, p. 10"/> and the Romanian Air Force also got one when a Soviet pilot defected.<ref>Stapfer 1996, p. 46.</ref> The Finnish Air Force (FAF) captured some I-16s (along with several other Soviet types). During the [[Winter War]] and the [[Continuation War]], the Finns captured six I-16s and one I-16UTI. Two of the captured I-16s and I-16UTIs were put back into flying condition and flight tested.<ref>Perttula, Pentti. [http://www.saunalahti.fi/~ambush/faf/fafincolor.html "FAF in Color."]{{dead link|date=January 2018 |bot=InternetArchiveBot |fix-attempted=yes }} ''saunalahti.fi''. Retrieved: 6 September 2009.</ref>