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The One that Got Away - the Elfin 50
The Elfin 50 was the smallest-ever member of the Elfin family of model diesels produced by Aerol Engineering of Henry Street, Liverpool 13, England. The history of this company has been recorded in great detail in my earlier article covering the career of company founder Frank Ellis, which may still be accessed on the late Ron Chernich’s “Model Engine News” (MEN) web-site. Readers wishing to know more about the company’s early years are referred to that article. However, for convenience I'll summarize the main points here. Background
Using these undeniably basic facilities, production of model engines commenced in mid 1947 with the introduction of the 2 cc Aerol Gremlin diesel. This was soon followed by an updated model called the Aerol Hurricane. My earlier article about the Aerol engines may be found elsewhere on this website.
Many years later in around 1990, family friend Jim Woodside taped an interview with company founder Frank Ellis in which Frank (then some 85 years old) was very forthcoming about this and many other matters relating to the affairs of Aerol Engineering. We all owe Jim an immense debt of gratitude for his care in preserving this material and for his kindness in making it available for study. My summary of this fascinating interview may be found on MEN in the previously-noted Frank Ellis tribute page. Frank Ellis took note of the very positive reception accorded to the Dart and decided at once that if the next British modelling fad was going to be ½ cc diesels, he was not going to be left out! He elected to enter this field himself with a new model which would prove to be his most openly Arden-influenced design of them all - the Elfin 50 which forms our main subject. Description The Elfin 50 was announced shortly after the appearance of the Dart, although its actual entry into the marketplace was delayed until January 1952, likely as a result of production difficulties, of which more anon. When it finally appeared, there could be no denying the fact that to all intents and purposes it was a reduced-scale diesel version of the famous Arden spark-ignition and glow-plug engines. It featured an identical conical radial mount with screw-in backplate, 360-degree porting, updraft FRV induction and an under-slung plastic tank, all derived directly from the Arden layout. The only major departures in fact were the use of compression ignition coupled with a plain bearing instead of the Arden’s twin ball races.
As supplied, the engine was clearly best adapted to free flight use - the standard tank would have been useless in a control line application. This may in fact have worked against it in terms of its marketplace acceptance. However, other factors appear to have contributed far more to its downfall, as we shall see in the following section. Production History The Elfin 50 was initially promoted quite vigorously, with advertisements appearing in “Aeromodeller” magazine more or less continuously from January 1952 to August 1952, after which it quietly disappeared from the market. It has always been assumed from this that the engine was not a success in the marketplace and was withdrawn for that reason. In fact, the real reason for the engine’s disappearance was far more complex.........
Frank recalled that initial tests on the Elfin 50 prototypes were extremely encouraging, showing that the little beastie could run with the best of them! Present-day experience bears this out completely - the engine is more than a match for any of its 1952 British half-cc competitors, including the Dart. But the problem was that like all small engines, the little 50 required an even higher degree of manufacturing precision than its larger relatives. And therein lay the problem! Despite intensive efforts, it proved impossible to manufacture this little engine in quantity using the tired equipment which was all that was available. An unacceptably high proportion of the completed engines proved to have manufacturing defects which precluded their being offered for sale. Frank recalled that even some of the ones which were released to the trade by Aerol Engineering were returned as un-saleable. The company had invested quite heavily in the new model - according to Frank, each new set of dies (which were It was clear that if the 50 was to remain in production, the company would have to invest in new machine tooling. However, they were still in debt for their expanded factory and existing equipment, hence being unable to finance the required new machinery themselves. Accordingly, they approached their original backer Colonel Davies once again. Davies-Benachi had continued throughout to handle the overseas distribution of the Elfin range, and Colonel Davies remained very well-disposed towards them. He readily agreed to back the financing of new equipment, which was duly ordered. Problem solved, it seemed! However, in one of those cruel twists of fate by which future events can be so greatly influenced, Colonel Davies unexpectedly died on May 5th, 1952 - the very day on which the new machinery arrived at Henry Street! Having lost their financial guarantor, the company had no recourse other than to send it straight back on the same truck. Frank’s quote from his 1990 interview with Jim Woodside: “If Colonel Davies hadn’t died when he did, that business (Aerol Engineering) would still be going today!” After this set-back, Frank decided that Aerol Engineering had no choice other than to cut their losses by ending production of the Elfin 50. This action was taken with extreme reluctance, since Frank sincerely believed in the merits of the design. However, he felt that there was no option, the consequence being that the engine suffered a premature demise, never coming close to repaying its development costs. We might re-phrase the earlier quote from Frank by saying that if Colonel Davies hadn’t died when he did, there would be far more surviving original examples of the Elfin 50 today!
Looking at this matter objectively with the benefit of hindsight, it actually appears to me to be quite probable that the engine would eventually have encountered a fair degree of sales resistance, Frank’s views notwithstanding. The more or less simultaneous entry of four British manufacturers into the ½ cc diesel field quickly resulted in an over-saturated buyers' market in which only the best could hope to survive. In performance terms, the Elfin was indeed up there with the best, but this was by no means the only factor affecting the engine’s sales potential. For one thing, the British marketplace had by then come down firmly in favor of beam mounting as the preferred installation arrangement. Moreover, the general layout with the under-slung tank forced the engine to be mounted in an upright position if the supplied tank was to be used. This would be OK for free flight, although the lack of a timer would have forced the use of the very basic and extremely imprecise “watch the level in the tank” method of flight timing. In addition, the engine’s relative bulk by comparison with its direct competitors as well as its radial mounting and inconvenient layout for mounting positions other than upright would likely have resulted in a progressive erosion of its position in the ½ cc marketplace unless modifications were made. However, other factors supervened before this could be put to the test. The Elfin 50’s tenure in the marketplace was so short that the engine was never the subject of a published test in the contemporary modelling media. I haven’t run my own example for some years now, but my notes record that it was pretty much comparable to the category-leading Allbon Dart in the performance department, with if anything a slight edge in torque production at the lower speeds. I may get around to a re-test at some point, in which case I will append the test results to this article if the opportunity still exists to do so. Conclusion
Due to the very low production which was actually achieved, the Elfin 50 is extremely rare today, especially in complete and original condition. Finding a good example is pretty much a matter of being in the right place at the right time with the right amount of purchasing power, a position in which I was fortunate enough to find myself on just one occasion in the dim and distant past.
Quite apart from their physical size, the VA "Elfins" are easily distinguishable from the originals due to the vapor-blasted finish used on their castings. Hence they are not really true replicas. However, like the Hende versions they are fine collectibles in their own right. ___________________________________ Article © Adrian C. Duncan, Coquitlam, British Columbia, Canada First published December 2014 |
Here we share a look at the 0.54 cc Elfin 50, a very rare little British diesel from the early 1950’s which showed great promise in design terms but failed to make the grade in the marketplace for a variety of reasons. In consequence, it is undoubtedly the most elusive and little-known member of the British ½ cc diesel family of its era. 
Aerol Engineering was established in late 1946 by a gentleman named Frank Ellis, with financial backing from Colonel Thomas E. H. Davies of the old-established Liverpool cotton brokerage firm of Davies, Benachie & Co. The Aerol company began life as an adjunct to a scrap metal business which Frank Ellis had previously established with a number of associates. The workshop was equipped with a small inventory of well-used machine tools which had given their best to the war effort before becoming surplus and hence cheaply available following the conclusion of hostilities. This well-worn equipment was originally housed in a lean-to metal shed in one corner of the scrapyard! Later an expanded brick-built factory was constructed on the same site.
The Aerol series was supplanted in mid 1948 by the first of the Elfin range, the iconic 1.8 cc model. Although the domestic distribution of the Elfin range was quickly taken up first by Henry J. Nicholls and later by KeilKraft, Davies-Benachi acted from the outset as their overseas distributors, adding this portfolio to their ongoing cotton brokerage business.
rate with the equipment available. However, the die-cast cases were less sturdy and far more prone to distortion than the earlier gravity die-cast components. In hindsight, Frank felt that they should have continued to develop their former designs, even if it meant accepting lower production rates.
his trend-setting 0.55 cc Dart model, thus setting a fashion for ½ cc diesels in England. 
Apart from the Arden-inspired features described above, the Elfin 50 was essentially a completely conventional radially-ported plain bearing FRV diesel of its day. As such, a detailed technical description does not appear warranted here. Although it was basically a very compact little engine, its bulk was considerably increased by the presence of the under-slung tank and radial backplate mount. Even with these features, checked weight all complete as illustrated without prop was only 1.5 ounces (42 gm).
In the above-mentioned recorded interview with Jim Woodside, Frank Ellis discussed this very point in some detail. As stated earlier, the machinery used to make the engines was well-used wartime surplus equipment which had given its best to the war effort, consequently having been obtained cheaply when Aerol Engineering started up in late 1946. Basically, it was knackered to begin with, and by early 1952 it was well past it, having put in a further 5 years of hard grind making Aerol and Elfin engines. This explains the fact that the Elfin engines were well known to be a bit spotty from a quality standpoint, although if you got a good one, it was really good. The designs were excellent - it was inconsistency of production standards that let them down.
Years later, at the time of his 1990 interview with Jim Woodside, Frank still held to the sincere belief that the Elfin 50 would have been a great success if they could have kept making it. He stated that the good ones that did get shipped found ready buyers and that market resistance was not a factor in his decision. As far as he could recall, the company only ended up selling a few hundred examples of the Elfin 50, which explains why it’s such a highly prized and high-priced item among today’s collectors. 
The Elfin range continued for a further 5 years, the highlight being the appearance of the 
As the model engine collecting movement gained momentum in the 1980’s and 1990’s, the scarcity of original examples opened up a market niche for replica productions of the engine. The noted Swedish enthusiast Arne Hende took up this challenge, arranging for the manufacture of a series of very faithful replicas of the Elfin 50 many years after the withdrawal from production of the original. Arne’s engines were made to a very high standard, hence being fine collectibles in their own right. There’s actually a better chance of finding one of his Elfin 50’s in mint condition than there is of finding a complete and original Aerol example.
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