Turbo-compound Deltic
The 'E.185' or 'Compound Deltic' turbo-compound variant was planned and a single prototype was built in 1956 and tested in 1957. This capitalised on Napier's experience with both the 'Nomad', and its increasing involvement with gas turbines. It used the Deltic as the gas generator inside a gas turbine, with both a twelve-stage axial compressor and a three stage gas turbine. Unlike the Nomad, this turbine was not mechanically coupled to the crankshaft but merely drove the compressor. It was hoped that it would produce 6,000 horsepower, with fuel economy and power-to-weight ratio 'second to none'. Predictions by the engineers closely connected with it were that connecting rod failure would be the limit on this power, failing at around 5,300 bhp. On test it actually produced 5,600 bhp before throwing a connecting rod through the crankcase just as predicted. Naval interest had waned by 1958 in favour of the pure gas turbine, despite its heavier fuel consumption, and no further development was carried out.
Read more about this topic: Napier Deltic