Complex sentence: Radlett Aerodrome was opened in 1929 as a grass aerodrome for Handley Page Civil Aircraft, the runway was extended in 1939 to enable production of Halifax bombers.
Split into simpler sentences: Radlett Aerodrome was opened in 1929 as a grass aerodrome for Handley Page Civil Aircraft. Its runway was extended in 1939 to enable production of Halifax bombers.