Polikarpov TIS

Polikarpov TIS

Picture - The second prototype (MA) of the TIS

Role: Heavy fighter
National origin: Soviet Union
Manufacturer: Polikarpov OKB
Designed by: Mikhail Yangel
First flight: September 1941
Status: canceled
Number built: 2

The Polkarpov TIS was a Soviet heavy fighter designed during World War II. Only two aircraft were built because its intended engine proved to be too unreliable to be placed into production. The program was canceled after the death of Nikolai Nikolaevich Polikarpov, the chief designer of the OKB, in 1944.

Design and development

The original request for proposals for a heavy escort fighter (Tyazholyy Istrebitel' Soprovozhdeniya) was received at the Polikarpov OKB in November 1938, but the press of work with the I-180 and SPB prototypes prevented any significant design work until the third quarter of 1940. Mikhail Yangel was appointed head designer, but his work was complicated by multiple changes in role from escort fighter to interceptor, dive bomber and to reconnaissance.

The prototype, internally designated as aircraft or TIS "A", was a low-wing, all-metal, cantilever monoplane with two Mikulin AM-37 engines and a twin tail. The monocoque fuselage had four 7.62 mm (0.300 in) ShKAS machine guns in the nose, each with 1,000 rounds. The pilot and the gunner/radio-operator were seated back-to-back, separated by an armor plate, under sliding canopies. The gunner had a dorsal ShKAS on a TSS-1 mount with 750 rounds that could be used once his canopy was slid forward. He also had a ventral ShKAS mounted below the armored floor which he could access by raising a hatch in the floor and kneeling down to fire the machine guns. The ventral gun was provided with 500 rounds of ammunition. A 12.7 mm (0.50 in) UBK machine gun with 400 rounds and a 20 mm (0.79 in) ShVAK cannon with 350 rounds was mounted in each wing root. Underneath the wings were two racks capable of carrying a single 500 kg (1,100 lb) FAB-500 bomb each. The wing had automatic leading edge slats and four split flaps separated by the engine nacelles. The single wheel landing gear retracted into the rear part of the nacelles, as did the tailwheel into the fuselage.

The 'A' prototype first flew in September 1941 and reached a speed of 555 km/h (345 mph) at 5,800 m (19,000 ft) altitude. It suffered from a lack of directional stability and the engines were unreliable and vibrated above 5,000 m (16,000 ft). Factory No. 51 attempted to fix the stability problem in late September by increasing the area of the rear fins, but was unsuccessful. Flight testing continued in October in Novosibirsk, where the LII (Russian: Лётно-исследовательский институт-Flight Research Institute) had been evacuated to. Eliminating the stability problem took until March 1942, although the engines remained as unreliable as ever.

By the summer of 1942 it was clear that the Mikulin OKB lacked the resources to fix the problems with the AM-37 and that the TIS would need a new engine, but the OKB's resources were fully utilized on the I-185 and ITP programs and the TIS program was put on hold. Work did not resume on the TIS until the second half of 1943, after the I-185 had been canceled, and the Mikulin AM-39 engine was selected. A new prototype was built, internally called the "MA", with a totally revised armament. Two ShVAK cannon replaced the nose ShKAS machine guns and a UBT machine gun in a VUB-1 mount replaced the dorsal ShKAS while the ventral machine gun was removed entirely. Two 37 mm (1.5 in) Shpitalny Sh-37 or 45 mm (1.8 in) 111P cannon replaced the wing root guns. The intended AM-39s were unavailable so two Mikulin AM-38Fs were used as a temporary expedient. The engine radiators were moved from the nacelles into the wings. They were fed by inlets in the leading edge and outlets on the undersurface of the wing.

Operational history

The "MA" was flight tested from June to September 1944 and generally met its expected performance figures. The engines were optimized for low altitudes and could only reach a maximum speed of 535 km/h (332 mph) and a ceiling of only 6,600 metres (21,700 ft). However it did have an initial climb rate of 13.5 m/s (44 ft/s) and, on the basis of the flight tests, it was concluded that it would be capable reaching 650 km/h (400 mph) at 7,150 m (23,460 ft) and would take 6.4 minutes to reach 5,000 metres (16,404 ft) once the AM-39s were fitted. A brake failure on 29 June damaged the "MA" which required a month to repair, but a crash-landing on 16 September caused by the failure of the undercarriage to extend proved to be the death knell for the TIS program as the OKB was being shut down after Polikarpov's death at the end of June and there was no one willing to champion the TIS.

Specifications (TIS (A))

Data from Gunston, The Osprey Encyclopedia of Russian Aircraft 1875-1995

General characteristics

Crew: 2
Length: 11.7 m (38 ft 5 in)
Wingspan: 15.5 m (50 ft 10 in)
Height: 3.73 m (12 ft 3 in)
Wing area: 34.8 m (375 sq ft)
Airfoil: NACA-230
Empty weight: 5,800 kg (12,787 lb)
Gross weight: 7,840 kg (17,284 lb)
Fuel capacity: 2,430 l (530 imp gal; 640 US gal)
Powerplant: 2 x� Mikulin AM-37 liquid-cooled V12 engines, 1,044 kW (1,400 hp) each
Propellers: 3-bladed VISh-61SF

Performance

Maximum speed: 555 km/h (345 mph; 300 kn)
Range: 1,720 km (1,069 mi; 929 nmi)
Service ceiling: 10,250 m (33,629 ft)
Time to altitude: 7.3 minutes to 5,000 m (16,404 ft)

Armament

Guns: 2 x 20 mm ShVAK cannon (wing roots)
2 x 12.7 mm UBK machine guns (wing roots)
4 x 7.62 mm ShKAS machine guns (nose)
Bombs: up to 1,000 kg (2,200 lb)

Comparable aircraft

Messerschmitt Bf 110
Messerschmitt Me 210
Mikoyan-Gurevich DIS
Petlyakov Pe-2
Westland Whirlwind

Bibliography

Gordon, Yefim. Soviet Airpower in World War 2. Hinckley, UK: Midland Publishing, 2008. ISBN 978-1-85780-304-4.
Gunston, Bill. The Osprey Encyclopedia of Russian Aircraft 1875-1995. London: Osprey, 1995. ISBN 1-85532-405-9.
Townend, David R. Clipped Wings - World War Two Edition. Markham, Ontario: Aerofile Publications, 2010. ISBN 978-0-9732020-1-4.

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Source: WikiPedia