The Soviets experimented with radial powered Yaks near the end of World War II because of overheating issues with the V12s they used up until then, but as mentioned above, this is a modern aircraft built to the same basic design.
Various models of the excellent World War II Russian fighter, including the Yak 3, were flown at the show.
Steadfast was made in Romania in 2005 and is based on the Soviet World War II Yak 3. It is powered by a Pratt and Whitney R-2000 radial engine, producing about 1750 hp. It set the world record speed for a piston powered aircraft under 3000 kg in weight at 655 km/h, and has unofficially reached 670 km/h.
The twin smoke generators on the wing tips provided a really effective smoke trail which tended to break into interesting patterns in the wind, including smoke rings.
The more standard, V12 powered Yak has quite different lines to Steadfast. These are popular aircraft and appear at many air shows.
Use the controller to watch a movie of the Yak flying past at the air show. This movie requires a modern browser supporting HTML5 (using the MP4 codec) and is fairly large (about 1.2 MB).
Sources: Wikipedia: Yak 3, Air and Space, Classic Fighters Omaka 2017 Programme.