The Yakovlev Yak-141, also known as the Yak-41, is a Soviet supersonic vertical takeoff/landing (VTOL) fighter aircraft designed by Yakovlev. Intended as a replacement for the Yak-38, it was designed as a supersonic fleet defence fighter capable of STOVL/VTOL operating from Soviet carriers.
source/image: Found And Explained
One key problem was designing an aircraft with both vectoring thrust and an afterburner, which was essential for sustained supersonic speeds. A twin-engine design was considered, but abandoned as the loss of an engine on landing would result in an immediate roll to the side.
Eventually it was decided that the best arrangement was a single vectoring nozzle located just behind the center of gravity, as well as dedicated vertical thrust jets positioned just behind the cockpit.Parts subject to excessive heat from the engines during landing were manufactured of titanium, and no less than 26% of the overall aircraft was to be manufactured of graphite or composite material.
The main engine was served by four side-mounted ducts as well as a row of large louvers along the upper surface to allow air to enter the engine during full power hovering. This engine was the R-79V-300, a two-shaft augmented turbofan with a bypass ratio of 1. Maximum thrust was 14,000 kg (30,864 lb). The rear nozzle could rotate from 0 degrees to 95 degrees for VTOL landing and hovering. The two lift engines were the RD-41 design, a simple single-shaft engine made mostly of titanium. Each had a thrust of 4,100 kg.