Tommy Cookers wrote: ↑
Fri Jun 08, 2018 11:43 am
the Nomad showed that CI with CR as low as a compounded SI engine's could use cheap fuel - but it was not more efficient
ie the Nomad 1 had the same 'best bte' as the Wright Turbo Compound (and the Nomad 2's was worse ?)
but diesel fuel seems to be not intrinsically cheap
normal piston engines are anyway compounded in flight at reasonable altitude and speed by inherent exhaust jet effect
Napier (and Wright) clearly claim merit only in relatively slow flight
the only significant CI (mechanically) compounded engine was/is a USSR 42 and 56 cylinder marine job - eg 5200 hp/unit
yes these to a greater or lesser extent benefit from heat dilution as does F1
the Nomad of course had multi-stage compressors and axial turbines - F1 limits itself to single stage
airliners operate in cruise with their altimeters set to 1013 millibar regardless of actual surface or sea level pressure
so eg Flight Level 360 means fictitious 36000' reading not 36000' actual
and the plane coming the other way will be flying at a similarly fictitious 37000' reading - so is seperated by an actual 1000'
Actually T-C, if you take the trouble to read the 'Flight' article..
- it is pointed out that the Wright 'blow-down' type of turbo-compound was fully efficient only over a narrow
operating band (while running on expensive hi-test avgas - 115/145 - & yet still hard on the limits of meltdown)..
By contrast, the Napier was more fuel efficient, & over the full range of engine operations (power settings
and altitude bands) while safe against detonation - on any available aviation fuel..
The Napier Deltic is a turbo-compound engine, others inc' Detroit Diesel & Volvo - are still in production.
Dr Moreau sez..
"Who breaks the law... goes back to the House of Pain!"