Unofficially dubbed Balalaika thanks to its resemblance in shape to the sound box of that musical instrument, the T-3 initiated the series of missile-armed single-seat tailed-delta interceptor fighters developed by Pavel Sukhoi's OKB. Evolved in parallel with the S-1 "frontal" fighter and first flown on 26 May 1956, the T-3 possessed 57° of wing leading-edge sweepback, was intended to be armed with two K-8 or K-9 missiles and was to have had an Almaz (Diamond) search-and-track radar. The elements of the Almaz were to have been housed within a broad elliptical radome above, and a circular housing on, the intake splitter plate. Powered initially by an unaugmented Lyulka AL-7 turbojet - which was to give place to an AL-7F rated at 6500kg boosted to 9060kg with afterburning - the T-3 was demonstrated over Tushino on 24 June 1956.
TsAGI wind tunnel testing of the efficiency of air intake/radar housing combinations being inconclusive, two further prototypes, the PT-7 and PT-8, were completed with different arrangements. The former, flown in September 1956, retained the chin intake position and superimposed elliptical radome, but with a variable-angle lower wedge to produce a two-dimensional intake. The PT-8, which joined the test programme two months later, featured a lengthened - by approximately 1.25m - nose with circular air intake and conical translating centrebody. The T-3 and its PT variations provided the basis for the further T-4 series from which the first production Sukhoi tailed-delta fighters were to be derived.
