Quote - "Presumably the reasoning behind the historical approach to the Vulture was 'we have most of the parts we will need, so the required development time and money will be reduced'.
How would RR have fared if it had decided to use a clean sheet as it did with the later Eagle?"
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I'm sure it was a case of "we have the parts, lets join them together" initially, but R-R soon found out that they needed to redesign quite a few of the standard Peregrine components. According to Alec Lumsden's "British Piston Engines and their Aircraft" (a snip at £39.95) one major problem was conrod failure, partly due to having the four big ends of each "row" of cylinders on a single crank pin. Another was the two coolant pumps starving each other of flow with the usual results of poor cooling.
Lumsden reckons the Vulture V was sorted put and would have been a success had it had a chance. Neither the time nor money to give it a chance was available
Saying that, there is a seven month gap in 1942 between Vulture termination and Eagle commencing, so perhaps R-R had a few ponderings on where to go next. Interesting how they came up with the H-layout with sleeve valves for the Eagle.
A clean sheet better? Undoubtedly, with the experience they had behind them by 1942. Perhaps R-R had more than enough to keep them busy on the clean sheet department with the Exe and the Crecy at the time they commenced the Vulture in the late 30s. One of Hives' reasons for scrapping the Vulture was to allow engineers to concentrate on other projects.
The perceived benefits of a single 3000hp engine over two 1500hp jobs are clear: less maintenance, single installation, etc etc. So it would be attractive on paper, but experience would prove otherwise and that's how engineering progresses: push a design until it breaks.
Joining two engines into one sounds great, but as Daimler-Benz found out with the DB.610, it's fraught with trouble. Perhaps the French had the right idea of using tandem engines. I sometimes wonder how long it took Volkswagen to bite the bullet and build the W12 engine for the Golf, Phaeton and the Bugatti Veyron. Or perhaps they never looked at a book on the He.177. Then again with 60 years of materials development and experience, such things must now be possible in a standard road car (not that I could ever describe the Veyron as standard).
I'd be interesting in hearing an alternative view from the US as I can't recall a US conjoined-engine project apart from the Chrysler IV-2220 for the XP-47H, which was two V8s in line I believe.
KB
