Description

An uprated Merlin engine was dropped in an Mk.I Spitfire in 1939. This 1,175 horsepower beast allowed the Spitfire to climb and fly faster while carrying heavier loads. Merlin-engined Mk.IIs went into full-rate production at a shadow factory near Birmingham in 1939. The advantage these new engines gave, though small, was exactly the kind of edge the RAF needed in the bloody days of the Battle of Britain.