Complex sentence: Experimental engines were developed as alternatives for high performance aircraft such as the H-24 configuration Rolls-Royce Eagle 22, the 2-stroke Rolls-Royce Crecy and the Rolls-Royce Pennine and Rolls-Royce Exe.
Split into simpler sentences: Experimental engines were developed as alternatives for high performance aircraft. The H-24 configuration Rolls-Royce Eagle 22, the 2-stroke Rolls-Royce Crecy and the Rolls-Royce Pennine and Rolls-Royce Exe.