Today’s wikisurfing led to this remarkable piece of information:
Early in its development, the Merlin engine’s lack of direct fuel injection meant that both Spitfires and Hurricanes, unlike the Bf 109E, were unable to simply nose down into a steep dive. This meant a Luftwaffe fighter could simply “bunt” into a high-power dive to escape an attack, leaving the Spitfire sputtering behind, as its fuel was forced by negative “g” out of the carburettor. RAF fighter pilots soon learned to “half-roll” their aircraft before diving to pursue their opponents. The use of carburettors was calculated to give a higher specific power output, due to the lower temperature, and hence the greater density, of the fuel/air mixture fed into the motor, compared to injected systems. In March 1941, a metal diaphragm with a hole in it was fitted across the float chambers. It partly cured the problem of fuel starvation in a dive, and became known as “Miss Shilling’s orifice” as it was invented by a female engineer, Beatrice “Tilly” Shilling.