1-224 / 4A

Considering its external layout and structure, the fourth offspring of the A family was not very different from the first, the 1-220, except that the heat exchanger bath was markedly larger. The 1-224 (4A) was pow­ered by an AM-39B engine that offered 1,288 kW (1,750 ch) at takeoff and 1,052 kW (1,430 ch) at 13,100 m (42,970 feet). It was fitted with an exhaust-driven TK-300B turbo-supercharger on the right side and drove a four-bladed AV-9L-22B propeller 3.5 m (11 feet, 5.8 inches) in diameter. (“Four-paddled” is probably more accurate: the blade chord was 400 mm [15.75 inches] at its maximum breadth.) For the first time, the pressurized cockpit was constructed of welded dural sheet. It was also air-conditioned and fitted with an inflatable seal bead. Air for the cockpit was tapped from the supercharger compressor; the cockpit overpressure was 0.3 kg/cm2 (4.27 psi). Air from the engine radiator was evacuated through four funnel-shaped variable exhausts on the upper surface of the wing. The armament was composed of two 20- mm ShVAK cannons (100 rpg) flanking the engine.

The 1-224 rolled out in September 1944, and A. P. Yakimov took it for its first flight on 20 October. Its speed at high altitudes was excellent, but its range (400 km [248 miles] shorter than expected) and its ceiling (400 m [1,310 feet] below that of the 1-222) were both disappointments.

Specifications

Span, 13 m (42 ft 7.8 in); length, 9.51 m (30 ft 0.2 in); height, 3.60 m (11 ft 9.7 in); wing area, 22.44 m2 (242 sq ft); empty weight, 3,105 kg (6,843 lb); takeoff weight, 3,780 kg (8,330 lb); max takeoff weight, 3,921 kg (8,642 lb); fuel, 476 kg (1,049 lb); wing loading, 168.5/174.7 kg/m2 (34.5/35.8 lb/sq ft); max operating limit load factor, 8.

Performance

Max speed, 693 km/h at 13,100 m (374 kt at 42,970 ft); max ground speed according to TOW, 574-601 km/h (310-325 kt); climb to 5,000

The 1-224 is quite similar to the basic aircraft of the family, the 1-220. The exhaust-driv­en turbo-supercharger was moved to the right side of the engine, and the heat exchanger was enlarged The sizable outlets for the engine radiator on the wing’s upper surface are quite noticeable

m (16,400 ft) in 4.8 min; service ceiling, 14,100 m (46,250 ft); landing speed, 127 km/h (69 kt); range, 1,000 km (620 mi); takeoff roll, 440 m (1,445 ft).