Interesting news - according to Sukhoi's insider Pavel Plunsky (co-author of splendid Ildar Bedretdinov's two-volume Su-27 history), SR-10 is not your ordinary startup aerospace company design, but, actually, Sukhoi Su-52 (S-52).
S-52 was a jet trainer proposal from the 1997-2001 timeframe, moving force behind this project was Andrey Manzheliy, who was working under the direction of Mikhail Simonov and Boris Rakitin. After 2001 project didn't gain momentum, and, as a result, Manzheliy has moved to SAP, where continues work on what now being called SR-10.
Sorry for the bad translation with a little help of OCR and AI. Maybe our Russian members will provide a better summery sometime soon.Sukhoi Design Bureau - 85th anniversary said:The Su-52 jet trainer project began in 1996 after the completion of the Su-49 piston training aircraft. Initially called SX, it was based on the RU19A-300 engine, originally created for the Yak-30 jet VTS. The project was shown to General Designer M.Ts. Simonov, who supported it, and B.V. Rakitin was appointed as the main constructor.
The Su-52 project aligned with the concept of training pilots and included three types of training complexes:
1. Initial training based on a piston VTC.
2. Basic training with a single-engine trainer using a turboprop engine.
3. Advanced training based on the MiG-AT and Yak-130 projects.
The Su-52 featured an original aerodynamic layout with a swept-back wing, allowing for a wider range of attack angles. Initially, it used the RU19A-300 engine and SKS-94 ejection seats, but these were later replaced with the AI-25TL engine and K-93 ejection seats.
In 1998, the first version of the project with the AI-25TL engine was launched, leading to a full-fledged preliminary project by 2000. However, after the completion of the preliminary project, further development within the Sukhoi Design Bureau did not continue.
In 2010, a private investor showed interest in this type of aircraft, leading to the creation of the SR-10 aircraft by the private design bureau BIM. The SR-10, unlike the Su-52, was a purely aerobatic aircraft without the complex on-board equipment necessary for training aircraft. The SR-10 was built and flown in 2015.