Talk:Bristol Hercules

Displacement
Math says 2,363 cuin, not just 2,360. 68.148.93.15 (talk) 06:22, 29 July 2012 (UTC)


 * Just as motor vehicle displacements are rounded to the nearest figure, litre often, so are aero-engine displacements. Are you rally worried about the missing 0.127% displacement? And they are cu in too, not cuin. Lin (talk) 08:35, 29 July 2012 (UTC)


 * Rounded to the nearest IS 2,363. MV engines are rarely off by more than 1 cubic inch (and that is mainly in the marketing) never mind 3. The nearest '5' is 2,365.:) AMCKen (talk) 06:05, 7 April 2013 (UTC)

Reliability confusion
This section needs a bit of improvement:
 * "Except for the 2000 hp-range versions in the 1950s until there were lubricating oil improvements, it was considered to be one of the more reliable aircraft engines of the era."

It is unclear when these oil improvements were introduced. It also infers that the 1950s engines were less than reliable but has no reference for either of these factoids. Looks like it was edited to reflect further information. Flanker235 (talk) 06:47, 24 August 2020 (UTC)

Design and Development
I have expanded this section to include more historical context and the difficulties of production. Flanker235 (talk) 16:06, 8 June 2021 (UTC)


 * That was a good improvement. A few comments if I may:
 * At that time, the tolerances were simply not sufficiently accurate to ensure the mass production of reliable engines.
 * The tolerances were set by Butler, who was a master at setting appropriate tolerances for each part of each Bristol engine. Possibly changing "tolerances were" to "machining was" may better reflect the situation.
 * Fedden drove his teams mercilessly, at both Bristol and its suppliers, and thousands of combinations of alloys and methods were tried before a process was discovered which used centrifugal casting to make the sleeves perfectly round.
 * I agree with Fedden being a very hard task master. There were 58 alloys and over 1100 heat treatments trialled before arriving at a suitable sleeve. The centrifugal casting did not produce the perfectly round cylinders, but the accidental discovery by an operator using a worn tool rather than a new tool that stumbled on the technique suitable for mass production. Interestingly Hassell quotes a date of March 1938 for the discovery, however the application for the patent for the machining technique was dated Feb 26, 1936.
 * This final success arrived just before the start of the Second World War.
 * As above, the mass production technique for the manufacturing of sleeves was ready in Feb 1936. There were plenty of other manufacturing, resourcing and capacity difficulties to be overcome prior to the Second World War, however sleeve manufacture technique was not one of them.
 * Your thoughts on the above?
 * Refs:
 * The Bristol Sleeve Valve Aero Engines, Patrick Hassell, RRHT.
 * Patent GB475864A "Improvements in or relating to the manufacture of sleeve valves for internal-combustion engines, or like cylindrical objects" Volumex (talk) 02:50, 21 February 2024 (UTC)