Editing Rolls-Royce Merlin (section)

=====Ejector exhausts=====
[[File:SpitEjectors.JPG|thumb|alt=The right side of an uncowled, installed aircraft engine, with details of the exhaust system|Merlin 55 ejector exhaust detail, Spitfire LF.VB, ''EP120'']]
The Merlin consumed an enormous volume of air at full power (equivalent to the volume of a [[single-decker bus]] per minute), and with the exhaust gases exiting at {{convert|1,300|mph|km/h|abbr=on}} it was realised that useful [[thrust]] could be gained simply by angling the gases backwards instead of venting sideways.

During tests, 70 [[pounds-force]] (310 [[newton (unit)|N]]; 32&nbsp;[[kilogram-force|kgf]]) thrust at {{convert|300|mph|kph|abbr=on}}, or roughly {{convert|70|hp|kW|abbr=on}} was obtained, which increased the level maximum speed of the Spitfire by {{convert|10|mph|kph|abbr=on}} to {{convert|360|mph|kph|abbr=on}}.<ref>Price 1982, p. 51.</ref> The first versions of the ejector exhausts featured round outlets, while subsequent versions of the system used "fishtail" style outlets, which marginally increased thrust and reduced exhaust glare for night flying.

In September 1937 the Spitfire prototype, ''[[Supermarine Spitfire (early Merlin powered variants)#Prototype K5054 (Supermarine Type 300)|K5054]],'' was fitted with ejector type exhausts. Later marks of the Spitfire used a variation of this exhaust system fitted with forward-facing intake ducts to distribute hot air out to the wing-mounted guns to prevent freezing and stoppages at high altitudes, replacing an earlier system that used heated air from the engine coolant radiator. The latter system had become ineffective due to improvements to the Merlin itself which allowed higher operating altitudes where air [[Lapse rate|temperatures are lower]].<ref>Tanner 1981, A.P.1565E, Vol.1, Section II.</ref> Ejector exhausts were also fitted to other Merlin-powered aircraft.