The Airco DH.9A was a British single-engine light bomber designed and first used shortly before the end of the First World War.
It was a development of the unsuccessful Airco DH.9 bomber, featuring a strengthened structure and,
crucially, replacing the under-powered and unreliable inline 6-cylinder Siddeley Puma engine of the DH.9
with the American V-12 Liberty engine. Wikipedia.