To meet a requirement for a lighter "frontal fighter" powered by the Rolls-Royce Derwent turbojet, the Lavochkin bureau evolved two designs, the La-172 and the La-174TK.
The La-172 was powered by an NII-1 turbojet (as the pre-series Soviet version of the Derwent was designated) rated at 1600kg, and entered flight test early in 1948, with armament comprising three 23-mm NS-23 cannon. Early in the test programme, while being flown by I Ye Fedorov, the La-172 suffered uncontrollable flutter at 8000m and entered a flat spin. Recovery was effected at 3000m, but the prototype was heavily damaged in a subsequent crash landing. Nevertheless, development was continued via the La-174D to result in the La-15.
Max take-off weight: 3708 kg / 8175 lb
Empty weight: 2433 kg / 5364 lb
Wingspan: 8.83 m / 28 ft 12 in
Length: 9.56 m / 31 ft 4 in
Wing area: 16.16 sq.m / 173.94 sq ft
Max. speed: 1040 km/h / 646 mph
Range: 1300 km / 808 miles