Sopwith Aviation Company
Mahl was born in Twickenham in Middlesex, England on 28 October 1889. By 1911 he was a motor engineer and he became the Chief Engineer to the Sopwith Aviation Company. Mahl married Winifred Day in 1912 in Wolverhampton. He worked as Howard Pixton's engineer when he won the 1914 Schneider Trophy.