Complex sentence: The Royal Aircraft Establishment was notably sceptical of Petter's swept wing concepts however, following the first flight of the SB.5 on 2 December 1952, the trials performed demonstrated the choice of a tailplane and a 60 degree wingsweep proved the design principles to be effective.
Split into simpler sentences: The Royal Aircraft Establishment was notably sceptical of Petter's swept wing concepts. However, following the first flight of the SB.5 on 2 December 1952, the trials demonstrated the choice of a tailplane and a 60 degree wingsweep and proved the design principles to be effective.