Editing Napier Nomad (section)

===Nomad II===
[[File:Napier Nomad ¾ front view.jpg|thumb|Front three-quarter view of a Nomad II]]
[[File:Napier Nomad Plan view.jpg|thumb|Topside view]] 
Even before the Nomad I was running, its successor, the '''Nomad II''' (E.145) Nomad 6, had already been designed. In this version an extra stage was added to the axial compressor/supercharger, eliminating the separate centrifugal part and the intercooler. The turbine (which also received an additional stage) was now only used to drive the compressor, and feed back any excess power to the main shaft using a [[Beier variable-ratio gear]];{{sfnp|''Flight'' (30 April 1954)|page=549}} the separate propeller from the turbine was deleted, just as the whole of the "[[afterburner]]" system with its valves etc. So the system was now like a combination of a mechanical [[supercharger]], and a [[turbocharger]] without any need for bypass. The result was smaller and considerably simpler: a single engine driving a single propeller.{{sfnp|Lumsden|2003|page=171}} Overall weight reduction was {{convert|1000|lb|abbr=on}}. The [[wet liner]]s of the cylinders of the Nomad I were changed for [[dry liner]]s.{{sfnp|''Flight'' (30 April 1954)|page=550}}

While the Nomad II was undergoing testing, a prototype [[Avro Shackleton]] was lent to Napier as a testbed. The engine proved bulky, like the Nomad I before it, and in the meantime several dummy engines were used on the Shackleton for various tests.

On an equivalent power basis, the Nomad II had an SFC of {{cvt|0.327|lb/hph|g/kWh}} at {{cvt|25000|ft}} cruise altitude.<ref name="DP195409">{{cite magazine |issn=1040-8878 |magazine=Diesel Progress |title=What's going on in England: Napier Nomad |url=https://archive.org/details/sim_diesel-progress_1954-09_20/page/56 |pages=56, 58 |publication-date=September 1954 |given=Hamish |surname=Ferguson}}</ref>

A further development, the Nomad Nm.7, of {{cvt|3500|shp|MW}} was announced in 1953.<ref name="FI19531106">{{cite magazine |url=http://www.flightglobal.com/pdfarchive/view/1953/1953%20-%201456.html |magazine=[[Flight International|Flight]] |title=Here and there |publication-date=November 6, 1953 |page=610 |url-status=dead |archive-date=April 13, 2016 |archive-url=https://web.archive.org/web/20160413032333/https://www.flightglobal.com/FlightPDFArchive/1953/1953%20-%201456.PDF}}</ref>

By 1954 interest in the Nomad was waning, and after the only project, the [[Avro Shackleton|Avro Type 719 Shackleton IV]], based on it was cancelled, work on the engine was ended in April 1955, after an expenditure of £5.1 million. The design was also considered for the [[Canadair Argus]], a similar [[maritime patrol aircraft]] being designed for the [[Royal Canadian Air Force]]. This design turned to the [[Wright R-3350 Duplex-Cyclone|Wright R-3350]], the design the Nomad was intending to best.

A Nomad II is on display at the [[Steven F. Udvar-Hazy Center]] in [[Virginia]].<ref>[https://airandspace.si.edu/collection-objects/napier-nomad-model-e-145-horizontally-opposed-diesel-engine/nasm_A19640017000 Steven F. Udvar-Hazy Center - Napier Nomad] Retrieved: 7 April 2020</ref>