enginehistory.org

[rinkol]

I noticed the scanned catalog of Sunbeam aero engines that was recently posted on the AEHS web site. What caught my attention was that the Arab V8 was prominently featured at a time (January 1920) when I would have thought that it would have been best left out of a marketing document. Published accounts of this engine all clearly describe completely unacceptable levels of vibration; a few also mention other problems of a design or manufacturing nature. In any case, this engine seems to have seen very little use despite being initially ordered in large numbers. Were the technical problems ever resolved? Or was someone trying to paper over a major failure?

[kmccutcheon]

I've never heard anything good about the Sunbeam Arab either. I think its appearance in a marketing document should be taken at face value --- simply an attempt to sell a flawed product. News didn't travel as fast in 1919 as it does now.
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Kimble D. McCutcheon

[klankenau]

You never hear anything good about Hispano copies, whether license built or otherwise. I think you have to take into consideration all of the problems Hispano itself was having, especially with the geared engines. Perhaps Birkigts' promotional efforts to maintain the perception of product superiority may have been part of the issue. Reading contemporary pilot reports is usually a good indication. In the case of engines, pilots occasionally comment on one being better than another, but I've never read where a pilot was referring to a Hispano built engine being better than a Wolseley Viper, for example. It would appear that a "dud" or "good" engine was not necessarily linked to one manufacturer.

[rinkol]

There is some interesting information at http://www.historywebsite.co.uk/Museum/Transport/planes/SunbeamEngines7.htm

While describing the engine as "one of the worst engines produced during the war", it goes on to note that some were sold abroad after the war.

Another reference (https://www.newcomen.com/wp-content/uploads/2012/12/Chapter-1-Mottram.pdf) while describing the Arab as plagiarized from the Hispano, suggests that the use of articulated rods contributed to vibration problems. Interestingly both engines were relatively short stroke designs by the standards of the time.