Complex sentence: In the initial development period the CL.20 exhibited over sensitive lateral control and was unable to exceed a height of 300ft,as a result a more powerful Niagra engine was fitted but this made little difference.
Split into simpler sentences: In the initial development period the CL.20 exhibited over sensitive lateral control and was unable to exceed a height of 300ft. To improve lift a more powerful Niagra engine was fitted but this made little difference.