On another forum (AoWW2) member here 'snowygrouch' has cited/presented evidencewuzak wrote: ↑Sun Jun 27, 2021 6:55 amIt was not a type test, but a Rolls-Royce test.
Lumsden, British Piston Aero-engines and Their Aircraft, claimed that the Vulture had been run to 3,000hp, but Rolls-Royce Heritage Trust could only confirm 2,500hp.
I don't know hoe successful derating the R was, considering there was no particular demand for it at the time while there was for Rolls-Royce's PV-12, which would become the Merlin.
I do not know if the Griffon I, as it was called, had master and slave or fork and blade rods. Possibly the former, as it was based on the 1931 version of the R.
The 1929 Rolls-Royce R and the Buzzard, on which it was based, used fork and blade rods.
Big end bearing failures during development for the 1931 Schneider Trophy led to the fork and blade rods being replaced with a master and slave arrangement.
But bearing technology was improving, with the steel backed bearing having been developed in the '20s and was likely available for the Griffon I (and PV-12), but not the R.
Rolls-Royce were, indeed, systematically de-bugging the Vulture. But there comes a point where using resources to fix the Vulture would cost their other programs - the Merlin and Griffon.
One proposal was to use pairs of fork and blade rods on each crank pin, meaning that two banks would be offset from the others. The advantage of this was that Rolls-Royce would be using proven technology. The disadvantage would be the amount of time and money required to re-engineer the engine and get it into production.
There were two "super Mosquitoes" proposed - one with twin Sabres, which did not go ahead due to engine supply issues, and one with twin Griffons, which was not thought to offer sufficient performance improvement over the original Mosquito (2 stage Merlins having been introduced and the bulged bomb bay to carry the 4,000lb HC bomb well underway) to warrant development.
Of course the 2,500hp+ versions didn't appear until very late in the war.
that the UK Air Min requested/required R/R to run production suitability tests on their
R-type, it failed the endurance evaluation, even when de-rated to run on regular fuel.
(During the`30s the early Merlin was proving very problematic, per 'ramp-head' dramas).
Perhaps this was a prompt for R/R to licence-build the GM-Allison steel shell-bearing,
yet the Napier Lion (designed by Rowledge, the same bloke who changed the R-type
to master/slave conrods - per his Lion) seemed to manage well enough, when it was
developed from a 450hp low-comp up through 10-1 & 800+hp (both N/A) to ~1400hp
blown to take the Land-Speed Record for the Cobb/Railton from the R-type holder.
(Maybe this was due to the Lion having crank-end feed lubrication, a feature which
'snowygrouch' credits the Junkers Jumo 213 with, as rationale for hacking power upgrades?)
Whatever production-related issues the Napier Sabre had, crankshaft/conrod design
didn't seem to be one of them (albeit later marks adopted Vandervell steel-shell types,
as a production expedient, as well as deletion of full crankshaft counter-weighting as
needless in a 24 cylinder engine - while ironically enough, Allison duly adopted it, along
with heavy-duty conrods as a durability measure).
Seems a tad odd surely, R/R cancelling their Vulture (esp' when reportedly nearly 'cured')
yet then put an inordinate effort into a 'too big, & too late' Sabre clone - instead?
Sabre boost levels were progressively increased, with commensurate power output,
& even the final service production units were cleared for +15lb boost on 100/130 avgas,
for well over 2500hp (more on ADI), & importantly, over 2000hp for extended periods.
Reading through period 'Flight/The Aeroplane' ads from 1944/46 it is interesting to
see how Bristol's claim to have the most powerful type-tested sleeve valve engine
didn't last long - with Napier's response that their Sabre was type tested at "3000hp+"!
@ tok-tokkie, I can duly report that Bristol ads claimed Centaurus oil consumption as
being "4 pints per hour" for most economical cruise, & double that for hard running...
For a liquid-cooled comparison - Wilkinson lists the oil consumption (in cruise) for the
final "3500hp" Sabre VII as "6 g/hp/hr & the "2300hp" Griffon 69 as "7 g/hp/hr" - FWIW.