This is an odd-looking 10 cc barstock diesel which appears on architectural grounds to be an example of the numerous prototypes known to have been constructed in the mid-1940’s by the pioneering English diesel developer George Court leading up to his development of the FROG 100 diesel of 1946-47. It has spent a considerable period of time in the hands of my Kiwi mate Dean Clarke of Cre8tionworx Engineering, who spent a lot of effort making an updated near-replica of the engine, also correcting a few issues with the original unit. A record of Dean’s efforts may be found here, including a video of the engine running! 

Like a number of George Court’s previously-identified diesel prototypes, this one is distinguished by the complete absence of any cooling fins – the need for such fins on a diesel was still a subject for debate in the mid-1940’s. It also features George’s “trade-mark” cylinder hold-down system using long studs, along with a bolt-on front end featuring FRV induction through an updraft carburettor. The fact that if leaned out it only runs for about a minute before clear evidence of overheating begins to present itself seems to settle the cooling fin debate quite effectively! That said, it can certainly sustain a long enough run for a typical free flight application, which was probably its anticipated use.

Nominal bore and stroke of this engine are 0.875 in. (22.22 mm) and 1.00 in. (25.4 mm) respectively for a nominal displacement of 9.85 cc, making it an unusually large diesel. It weighs in at a very ponderable 449 gm (15.84 ounces). Court is known to have produced diesel prototypes of up to 20 cc displacement, making this by no means his largest such unit, assuming that it is his work. It’s quite true that the identification of this engine as George Court’s work can’t be substantiated by any direct evidence, but I’m unable to think of any more likely candidate. Can any reader do better?