9th February 2021 10:37 am 9th February 2021 10:37 am Beatrice Shilling’s engineering fix to a major design flaw in World War Two Hurricane and Spitfire fighter plane engines contributed to the eventual outcome of the Battle of Britain. Written by Nick Smith It was only a brass washer in the shape of a thimble. But it stopped Britain’s Merlin engine carburettors flooding in temporary negative-g manoeuvres such as a nosedive or inverted flight. While the RAF toiled over a long-term solution to their engines cutting out in combat, an engineer by the name of Beatrice Shilling pulled a rabbit out of the hat in the form of an ingenious workaround. Her ‘RAE Restrictor’ had been designed to allow just enough fuel to maintain power while preventing flooding, and crucially, the device could be fitted without removing planes from operation. RAF pilots referred to the innovation as ‘Mrs Shilling’s Orifice’, a ribaldry that has amused engineering students of a certain mindset for more than half a century. Saddled with the unflattering nickname of Tilly – ‘tillies’ were ‘utilitarian’ vehicles used in the armed forces – Shilling rose above the inevitable sexism that accompanied women engineers in a male dominated profession, not only to do her bit for the war effort, but also to become a ‘flaming pathfinder of Women’s Lib’, as well as a leading motorbike racer (and one of the few women to be awarded the Brooklands Gold Star).