Complex sentence: Despite the engine problems, the Siskin displayed good performance and handling, and it was decided to fit an alternative engine, the Siddeley Jaguar, the Jaguar-powered Siskin first flying on 20 March 1921.
Split into simpler sentences: Despite the engine problems, the Siskin displayed good performance and handling, and it was decided to fit an alternative engine. The engine chosen was the Siddeley Jaguar, the Jaguar-powered Siskin first flying on 20 March 1921.