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Before any decision was taken as to which fighter should succeed the I-3 on the production lines it was decided in the 1928 Experimental Aircraft Plan to build the I-5 with a radial engine and mixed wood and metal construction for comparison with the all-wood I-6. Whilst speed was a major consideration, there were two other factors for the designers to take into account; the first was to maximise manoeuvrability and the second, to ensure the fighter's adaptability to mass production methods. The original instructions stipulated that the I-6 prototype be ready by 1st August and the I-5 by 1st September 1929 but neither of these deadlines was met. This double failure may have provided the excuse for the OGPU (Soviet Secret Police) to incarcerate Polikarpov on grounds of industrial sabotage rather than to attribute it to inefficiency.
Design work on what was to become the I-5 had been started by Pavel O. Sukhoi under the supervision of Andrey N. Tupolev where the prototype was to have been designated ANT-12, the letters being Tupolev's initials. The formation of 'internal prison' design teams by the OGPU meant that someone more powerful even than Tupolev was now influencing the choice of chief designer. It is not known for certain why the internal prison design bureau (KB 'VT') was finally given the job of designing the I-5 but the most plausible explanation for this decision is the influence of the OGPU.
An alternative suggestion was that Tupolev preferred to concentrate on the development of heavy bombers and did not press the case for his bureau to keep the I-5 project. At the KB 'VT' Dmitriy P. Grigorovich was chosen as chief designer, but Polikarpov soon convinced Goriyanov of the OGPU, who was nominally in charge of the KB, that his fighter concept was superior to that of Grigorovich. Polikarpov was accordingly placed in charge of the design team which in early 1930 moved to hangar No.7 at factory 39.
The full-scale mock-up was approved on 28th March 1930. Just a month later the first prototype, designated VT-11, was completed and delivered to Moscow's Central Airfield (Khodynka) for testing.
It was a single-bay sesquiplane powered by an imported 450-hp (336-kW) supercharged Bristol Jupiter VII engine with a helmeted cowl and a 2.9-m (9.5-ft) propeller. The aircraft exterior was finished in silver dope with a red cheat line and adorned by a red 'VT' logo inserted in the red star on the rudder. Its first flight took place on 29th April 1930 with V. L. Bukhgolts at the controls.
A second prototype, known as VT-12, was built with an unsupercharged Bristol Jupiter VI engine, larger rubber shock absorbers on the main undercarriage legs and a shorter vertical tail with a more rounded top. The aircraft was doped green, with the dedication 'Klim Voroshilov' emblazoned in large white letters on the sides of the fuselage.
Both these prototypes had large spinners and each engine cylinder head was fully covered by a helmet-cowling but the third prototype, aircraft VT-13, which first flew on 1st July 1930 had no spinner and a NACA cowling fully covering the cylinder heads of a locally manufactured 600-hp (448-kW) M-15 engine.
Radiator slats gave improved cooling and the rear fuselage from behind the cockpit was built up to enhance the aerodynamics and give the pilot better protection. This latest aircraft was again doped silver with a red rudder and was given a large red pennant bearing the dedication 'A gift to the 16th Congress of the [Communist] Party.’ Such 'gifts' were common practice in the Soviet Union.
During the month between 13th July and 13th August 1931 the second prototype successfully underwent its State Acceptance Trials and on 13th September 1931 was formally ordered into production at factory No. 21 named after Sergo Ordzhonikidze in Gorkiy (now Nizhniy Novgorod) and factory 1 at Khodynka.
One fault noted in the State Acceptance Trials was the tendency of the aircraft to execute an uncontrolled 180 degree turn when landing in light wind conditions. Compensating with rudder movement broke the outer wheel on the turn, causing the fighter to stand on its nose or flip over. Even experienced pilots, such as the Commander-in-Chief of the Armed Forces Yakov I. Alksnis, experienced this problem. I. F. Petrov, an engineer from Army Scientific Research Unit, suggested shortening the undercarriage by 15 cm (5.9 in.) and positioning it 12 cm (4.75 in.) further forward. This was tried and found to be effective, as Alksnis himself confirmed. All existing and future production aircraft were given this undercarriage design and Petrov was awarded the Order of the Red Star for his ingenuity.
In the expectation of improving manoeuvrability a small number of aircraft had experimental streamlined leading wing struts which swivelled about their vertical axis in conjunction with rudder movement. This was not a success.
To reduce the number of accidents that had resulted from pilots being unable to control a spinning aircraft a spin test programme was carried out at Soviet Air Force Research Unit. Test pilots Piotr M. Stefanovsky, A. I. Filin and P. M. Stepanchonok were involved and it was during this programme that Stepanchonok was forced to bail out when he lost control in an inverted spin. It was as a direct consequence of the bravery of the test pilots that a set of safe spin recovery procedures could be issued. An interesting sequel was the formation of the first Soviet aerobatic demonstration team under the leadership of Stepanchonok.
New aircraft deliveries to the Armed Forces started in late 1931 and by the time that 1932 drew to a close the I-5 comprised 20% of its fighter force, a percentage which grew to 40% by the end of 1933, making the I-5 the most numerous fighter then in service. The Leningrad, Ukraine and Trans-Baikal Military Districts were the first to receive them, followed shortly after by the Far East, Belarusian and Moscow Military Districts. The resources of the last mentioned were strengthened in 1933 when the 10th lAB (Fighter Brigade) based at Lyubertsy and lvanovo began re-equipping with the I-5. By the end of 1934 most of the I-3 and I-4 fighters in the Soviet Air Forces had been replaced and deliveries of the I-5 had commenced to units of the Navy.
The I-5 was a demanding aeroplane to fly, and there were other peculiarities into the bargain. This is how the late Mark L. Gallai, the famous Soviet test pilot, described it in his book My Flight Log:
After flying it I was convinced that the I-5 is quite a handful, a capricious aircraft. However, if you are careful with the controls and do not offend the machine with rough actions, it will not depart from controlled flight. What annoyed me a lot more was the absolutely revolting smell it emitted. The M-22 engine was lubricated with castor oil. I hope you never had to smell burnt castor oil... During my long aviation career I never had a more disgusting job than to scrape off dead locusts that had become stuck to the underside of the I-5's wings. Locust fried in castor oil sure is a dish to make you faint.
Many new and innovative weapons were tested, using the I-5 as a carrier. Small 8-kg (17.6-lb) anti-aircraft bombs were dropped on a towed target drogue by an I-5 of the 5th lAB in Kiev during the summer of 1934. A primitive unguided rocket known as the Flute was carried in clusters of five under each lower wing of an I-5 and test-fired. Another interesting experiment was the ground testing of 82-mm (3.2-in.) RS-82 rockets (raketnyy snaryad - rocket projectile) fired from a triple under-wing launcher attached to both inner and outer portions of the lower wings with the aircraft securely attached to a firm base. In this way the accuracy of the rocket could be accurately assessed. Later, six rockets were fired at both aerial and ground targets from each of two airborne I-5s. Altogether 692 RS-82 rockets were expended in these trials and the weapon was used successfully in World War Two.
Aircraft development accelerated during the 1930s and the realization of how far it had advanced in Western Europe was brought home to the Soviets in the summer of 1934 during a visit by Pierre Cotte, the French Minister for Aviation. After his arrival at Kiev in a Caudron C.635 Simoun four-seat monoplane he was given an honorary escort of I-5 fighters for the next leg of his journey. Unfortunately the escorting I-5s were not fast enough to keep up with the Simoun and were compelled to turn back.
Aggressive Japanese tactics in Mongolia during 1937 resulted in squadron number 21, with both interceptor and ground attack flights, being deployed to Tamar-Bulak for border patrols. This apparent show of strength did not deter the Japanese because they had on hand a strong force of Kawasaki Ki-10, Army Type 92 biplanes and Nakajima Army Type 91 parasol monoplanes. No evidence of confrontation between these types of Soviet and Japanese aeroplanes has been found, which was opportune because the Japanese biplane was more manoeuvrable than the I-5 and their monoplane faster.
When Vladimir S. Vakhmistrov started his Zveno (flight, as a tactical unit) experiments in 1933 the I-5 was involved. To protect long-range bombers from enemy fighters an I-4, later replaced by an I-5, was carried under each wing of a Tupolev TB-1 twin-engined bomber piloted by Piotr M. Stefanovskiy. Flying the parasite fighters were I. F. Grozd and Vladimir K. Kokkinaki. Further trials were conducted with Zveno-2, using the four-engined TB-3 with two I-5s on top of the wings and a third on the fuselage. At an air display which took place at Monino in November 1935, a six-aircraft Zveno was displayed: a TB-3 carried two I-5s on top of the wings, two I-16s underneath and a Grigorovich I-Z which flew onto an under-fuselage trapeze. All five fighters were then safely released. (Whilst this concept is basically flawed in that the extra drag of the 'parasites' reduced the speed of the escorted bomber force to an unacceptable level, it was successfully used for a low-level bombing attack by a combat unit known as Zveno-SPB in which a TB-3 carried two I-16 type 5 fighters armed with bombs (these were known as SPB, fast dive-bomber). Its moment of glory was the destruction of a key railway bridge over the Danube at Chernovod, Romania, on 25th August 1941 and a number of other operations were also completed from bases in the Crimea.)
A fighter-bomber version of the I-5 was developed at Piotr I. Grokhovskiy's bureau. Beam-type bomb racks were designed for installation under the lower wings to carry two 250-kg (550-lb) bombs. One of the tests involved the aircraft diving down close to the target - the first time dive-bombing had been tried in the Soviet Union. Unfortunately the extra weight and drag of the bombs adversely affected performance to the extent that the I-5 fighter-bomber concept was rejected at the time, although it was resurrected during World War Two after the Luftwaffe had proved its effectiveness.
As new and more potent fighters such as the I-15 and I-16 entered service with the Soviet Air Force, the I-5 was increasingly used as a fighter transition trainer; pupils starting on the Polikarpov U-2 moved on to the Yakovlev UT-2, followed by a stint on the I-5 before graduating to the I-15 or I-16. The Air Force Academy named after Nikolay Zhukovskiy received eight I-5s in 1933 but more were transferred to other flying schools in large numbers, starting in 1936 at Borisoglebsk and Kacha. By the end of 1937 all I-5 aircraft had been phased out of service with first-line units.
Enormous losses of aircraft in the opening attacks of the German invasion of the Soviet Union and later the disruption of aircraft production led to use of this obsolete fighter as a ground attack aircraft and night bomber. This would be the first time the type had been used in action. Many of the surviving I-5s were given an additional pair of machine-guns during the war as an alternative to carrying bombs. Possibly the most desperate time for the USSR was at the end of 1941 and the beginning of 1942 when the shortage of aircraft was so acute that almost anything that could fly was pressed into service and there are records of 605th and 606th lAPs (fighter regiments) using the I-5 on night bomber operations in the Battle for Moscow. Based at Bykovo, Pushkino and Klin, they continued in service until replaced by a more modern type in February 1942. In September 1941 the 2nd ShAP (attack air regiment) was formed from Crimean Front Air Force reserve personnel and equipped with 32 I-5s for ground attack. These aircraft were found in flying schools and returned to airworthy condition by the regiment for use in the Crimea, soldiering on until January 1942 when the regiment was withdrawn to Chapayevsk for conversion to the lIyushin IL-2 and redesignated the 766th ShAP.
The Black Sea Fleet Air Arm used refurbished I-5 fighters and in November 1941 they represented half of its entire fighter inventory which in total was only 44. One regiment was the 11th ShAP commanded by Major I. M. Rassoodkov which covered the Red Army's retreat to Sevastopol. Captain N. T. Khrustalyov led 20 I-5s in ground attacks against enemy troops and armour in the Belbek Valley and deliberately dived his blazing plane onto them when it was certain that he could not avoid crashing.
Regrettably no I-5 fighters are still in existence, but a 3/4 scale replica powered by a 36-hp flat-twin engine from a Dnepr MT-1 0-36 motorcycle was built in 1989 by the Ivanovo-based company NPO Antares. It was shown at Moscow-Khodynka in August 1989 and in the static line at the 1993 Moscow Air Show. The aircraft was painted to represent the I-5 flown by Russian Civil War hero I. U. Pavlov.
Y. Gordon and K. Dexter
