Editing Dewoitine D.520 (section)

===Engine===
The [[Hispano-Suiza 12Y]]-45 engine was an underpowered, older design, with {{cvt|850|CV|kW hp}} at takeoff at 2,400 rpm, or {{cvt|935|CV|kW hp}} emergency power at 2,520 rpm and at a height of {{cvt|1900|m}}.<ref>Danel and Cuny 1966, p. 248.</ref> The Hispano engine had some advantages over some later engines; for example, its weight was only {{cvt|515|kg}}, compared to the {{cvt|620|kg}} of the [[Rolls-Royce Merlin]] III. Development of the engine had not been straightforward, and had delayed production.<ref name="Danel 5 6"/> According to an aviation author, it was alleged by American aviator [[Charles Lindbergh]] that secret negotiations were conducted between Dewoitine and [[Daimler-Benz]] during 1939 to obtain the DB.601 engine for the D.520, but that these did not come to fruition due to the war.<ref name="Danel 5"/>

Fuel was fed via six [[Solex Carburetor|Solex]] S.V. 56 carburettors mounted on an inlet manifold which directed compressed air from the supercharger to the engine cylinders; the 12Y-45 and -49s fitted to production D.520s used either [[octane rating|92 or 100 octane]] fuel.<ref>Danel and Cuny 1966, pp. 72, 245, 303.</ref> The -45 drove an electrically operated [[Ratier Type 1606M]] three-bladed, {{convert|3|m|ft|-diameter|adj=mid}}, variable-pitch propeller, while D.520s from No. 351 were fitted with the 12Y-49 {{cvt|960|CV|kW hp}} engine driving a [[Chauvière type 3918]] pneumatically operated propeller, {{cvt|3|m}} in diameter.<ref>Danel and Cuny 1966, pp. 227, 228.</ref>

By 1940 a version of the 520D was flying with a Rolls-Royce Merlin X engine. [[Ernest Hives]] stated that agreement had been reached with the French Government for the manufacture of the Merlin in France. ("The Merlin in perspective" - A Harvey-Bailey -Rolls-Royce Heritage Trust, p130)