The maiden flight of the T-49 prototype took place in January 1960, after various rolling tests in October 1959.

Since this also gave the plane a larger diameter than the Su-11, it was no longer possible to accommodate the radar antenna in the shock cone of the air inlet.

This also simplified the operation of the radar, since its antenna was now firmly installed in the aircraft nose and the forward and backward movements of the engine shock cone no longer had to be compensated for.

[2] The flight tests with the T-49 were promising but showed that the twin-engined project T-58 had a greater potential.

In the air intakes, this helped the T-58 gain a development advantage over the competing design of the Yak-28-64.