Editing Rolls-Royce Merlin (section)

=====Carburettor developments=====
[[File:Cavanaugh Flight Museum-2008-10-29-027 (4270566340).jpg|thumb|Preserved Merlin 63 showing [[intercooler]] radiator, [[supercharger]] and [[carburettor]]]]
The use of [[Carburetor|carburettors]] was calculated to give a higher [[Power density|specific power]] output, due to the lower temperature, hence greater density, of the fuel/air mixture compared to injected systems.<ref>Hooker 1984, p. 62.</ref> Initially Merlins were fitted with float controlled carburettors. However, during the Battle of Britain it was found that if [[Supermarine Spitfire|Spitfires]] or [[Hawker Hurricane|Hurricanes]] were to [[Flight dynamics (aircraft)|pitch]] nose down into a steep dive, negative [[g-force|''g''-force]] (''g'') produced temporary fuel starvation causing the engine to cut-out momentarily. By comparison, the contemporary [[Messerschmitt Bf 109|Bf 109E]], which had [[Gasoline direct injection#Early systems|direct fuel injection]], could "bunt" straight into a high-power dive to escape attack. RAF fighter pilots soon learned to avoid this with a "half-roll" of their aircraft before diving in pursuit.<ref>McKinstry 2007, p. 205.</ref> A restrictor in the fuel supply line together with a diaphragm fitted in the float chamber, jocularly nicknamed "[[Miss Shilling's orifice]]",{{#tag:ref|Invented in March 1941 by [[Beatrice Shilling]], an engineer at the [[Royal Aircraft Establishment]], Farnborough.|group=nb}} after its inventor, went some way towards curing fuel starvation in a dive by containing fuel under negative G; however, at less than maximum power a fuel-rich mixture still resulted. Another improvement was made by moving the fuel outlet from the bottom of the [[SU carburetor|S.U. carburettor]] to exactly halfway up the side, which allowed the fuel to flow equally well under negative or positive g.<ref>Smallwood 1996, p. 135.</ref>

Further improvements were introduced throughout the Merlin range: 1943 saw the introduction of a [[Bendix Corporation|Bendix-Stromberg]] [[pressure carburetor|pressure carburettor]] that injected fuel at 5 [[pounds per square inch]] (34&nbsp;[[kilopascal|kPa]]; 0.34 [[Bar (unit)|bar]]) through a nozzle directly into the supercharger, and was fitted to Merlin 66, 70, 76, 77 and 85 variants. The final development, which was fitted to the 100-series Merlins, was an S.U. [[Fuel injection#Throttle body injection|injection carburettor]] that injected fuel into the supercharger using a fuel pump driven as a function of crankshaft speed and engine pressures.<ref>Lumsden 2003, p. 212.</ref>