Editing Turbojet (section)

== Cycle improvements ==
The operation of a turbojet is modelled approximately by the [[Brayton cycle]].

The efficiency of a gas turbine is increased by raising the overall pressure ratio, requiring higher-temperature compressor materials, and raising the turbine entry temperature, requiring better turbine materials and/or improved vane/blade cooling. It is also increased by reducing the losses as the flow progresses from the intake to the propelling nozzle. These losses are quantified by compressor and turbine efficiencies and ducting pressure losses. 
When used in a turbojet application, where the output from the gas turbine is used in a propelling nozzle, raising the turbine temperature increases the jet velocity. At normal subsonic speeds this reduces the propulsive efficiency, giving an overall loss, as reflected by the higher fuel consumption, or SFC.<ref>{{cite book | last1=Cohen | first1=Henry | last2=Rogers | first2=Gordon Frederick Crichton | last3=Saravanamuttoo | first3=H. I. H. | title=Gas Turbine Theory | publisher=Longman | publication-place=London | date=1972 | isbn=0-582-44927-8 | at=pp. 72-73, fig 3.11}}</ref> However, for supersonic aircraft this can be beneficial, and is part of the reason why the Concorde employed turbojets.
Turbojet systems are complex systems therefore to secure optimal function of such system, there is a call for the newer models being developed to advance its control systems to implement the newest knowledge from the areas of automation, so increase its safety and effectiveness.<ref>{{cite conference | last1=Andoga | first1=R. | last2=Fozo | first2=L. | last3=Madarasz | first3=L. | last4=Judicak | first4=J. | title=2010 IEEE 8th International Symposium on Applied Machine Intelligence and Informatics (SAMI) | chapter=Advanced methods of turbojet engines' control | publisher=IEEE | date=2010 | page= | isbn=978-1-4244-6422-7 | doi=10.1109/SAMI.2010.5423749 | chapter-url=https://ieeexplore.ieee.org/document/5423749 | pages=141–144}}
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