Sukhoi P Prototype
In January 1948 the Soviet air force issued a requirement for an all-weather interceptor, and among the several designs submitted was one from Sukhoi. This was developed as the Aircraft P prototype with 35 degree swept flying surfaces and the same tandem arrangement of engines as used in the competing La-200 and I-320. Sukhoi was the first of the competing bureau to get a prototype into the air, in January 1949. The prototype revealed good performance, but suffered from problems and when the aeroplane was lost as a result of flutter- induced structural failure the programme for a possible Su-15 production model was cancelled.