The final development of this straight-winged series was the La-174TK, which first flew January 1948 as a research type for the investigation of very thin, straight wings as an alternative to swept wings in overcoming compressibility problems.
The wing possessed a thickness ratio of only 6% (the "TK" suffix indicating Tonkoye Krylo, or Thin Wing) which the Lavochkin bureau believed might offer most of the advantages of a thicker sweptback wing while avoiding some of its disadvantages. The 6 per cent thickness/chord ratio was the smallest in the world at that time, and yielded performance benefits over the La-56. The basic configuration of the La-174TK reverted to that of the earlier La-152 series fighters, although the relationship was confined to a common design origin, with the single 1590kg NII-1 (RD-500) turbojet exhausting under the rear fuselage. Armament comprised three 23mm NS-23 cannon and flight testing commenced early 1948. Although lighter than the La-172, the La-174TK demonstrated inferior handling and performance characteristics, further development being discontinued.
The La-174TK was intended only for research and no production was ever planned.
Engine: 1590kg NII-1 (RD-500) turbojet
Wingspan: 8.64 m / 28 ft 4 in
Length: 9.41 m / 30 ft 10 in
Wing area: 13.52 sq.m / 145.53 sq ft
Max take-off weight: 3315 kg / 7308 lb
Empty weight: 2310 kg / 5093 lb
Max. speed: 970 km/h / 603 mph
Range: 960 km / 597 miles