 The first of two Yak-30 prototypes was given callsign "42", and the number "5" painted on the rudder.This aircraft was successfully test-flown on 4 September 1948 by pilot Anokhin, who continued test-flying the aircraft until 16 December 1948.The second prototype, the Yak-30D, which joined the flight test programme early in 1949, had a 38 cm (15 in) section inserted in the aft fuselage, revised mainwheel doors forming a large section of the fuselage skinning, Fowler-type flaps in place of split flaps, increased fuel and ammunition capacity, and changes to the oxygen system and radio equipment.