Which came first, the Eagle or the Merc ?

Through the thoughtfulness of that great enthusiast and historian, Hugh Conway, we were able to read an article entitled “Reminiscences of 50 Years in the Field of Aircraft Propulsion,” written by Sir Roy Fedden, Honorary Fellow, for the journal of the Royal Aeronautical Society.

In the course of this long and interesting article Sir Roy writes about the 1914 G.P. Mercedes racing car, which, thought to be the winning car driven by Lautenschlager, was, as is well known, sent to Derby on the outbreak of war for its engine to be examined by Rolls-Royce Ltd., was reassembled and raced by Count Louis Zborowski and Brocklebank, and is today owned (through a link with the Editor of Motor Sport—but that is a long story!) by V.S.C.C. Committee Member Philip Mann.

What is so interesting about Sir Roy Fedden’s reference to this Mercedes racing car is that he tells us that Engineer-Commander Wilfred Briggs, then Head of the Engine Section Of the Admiralty’s Aircraft Design Department, whose offices were over the Admiralty Arch, personally towed the car from the British Mercedes’ showrooms in Shaftesbury Avenue, where it had been on display, to Derby on the Sunday on which war was declared.

It is said that Rolls-Royce were instructed to employ the unusual Mercedes cylinder and valve construction, and any other characteristics they thought it desirable to incorporate, in making the in-line, water-cooled aero engines this Company had been asked to build for war service. Sir Roy continues : “The result was the 6-cylinder Hawk, 12-cylinder Falcon and 12-cylinder Eagle, which at the end of the war were the most refined family of aero engines the Allies possessed, being fitted to such successful aircraft as the Bristol Fighter, the Handley Page 0/400 and Vickers Vimy bombers, as well as many others. Actually, this same form of cylinder construction was used in nearly all the German aero engines and also in the Liberty engine developed by Packard in the U.S.A.” This raises the query, which came first, the Eagle or the Merc.?

Because, although there is no doubt about this race-winning o.h.c. Mercedes going to Rolls-Royce in 1914, the first Rolls-Royce aero engine was the highly successful Eagle, which appeared in October 1915—but could a complete copy of the 4 1/2-litre Mercedes racing-car unit, which produced 115 b.h.p. at 2,800 r.p.m., have been developed into a 20-litre V-12 power unit giving, in its original form, 225 b.h.p. at 1,800r.p.m., in the short space of 14 months ? Under the pressure of war, and with Sir Henry Royce’s previous experience of aero-engine production, making V8 Renault engines, possibly it could, but the fact remains that the 75-h.p. Rolls-Royce Hawk airship motor, which, as a small 6-cylinder engine would have been closer to the G.P. Mercedes concept, was produced after the Eagle.

However, the Eagle engine, which ultimately developed 360 b.h.p., had, I believe, the separate forged steel cylinders with welded-on water jackets and shaft-driven single overhead camshaft valve gear of the racing Mercedes design.

Another significant off-shoot is that the Fishponds plant of Sir Roy Fedden’s company, Basil Straker, was taken over by the Admiralty in 1915 and eventually built Rolls-Royce Hawk and Falcon aero engines and parts for the Eagle; says Sir Roy, “We were, in fact, the only firm other than Rolls-Royce themselves allowed to produce complete engines. . . . I also went to St. Margaret’s Bay near Dover to meet Mr.. Royce, and to discuss engine problems with such people as Hives, Harvey-Bailey and Platford.” So is it surprising that the construction of the post-Armistice Straker-Squire Six car engine also is closely allied to 1915/18 Rolls-Royce aero engine design—and to the 1914 G.P. Mercedes ?. Incidentally, Mr. Mann also owns two of these Straker-Squire cars.—W. B.

V.-E.-V. Odds and Ends.
We have commented previously on the nostalgic names given to new roads adjacent to the now defunct Brooklands Motor Course at Weybridge. But did you know that roads round Stag Lane Edgware, once the de Havilland aerodrome, are called De Havilland Road, Mollison Avenue and Amy Johnson Court ? We apologise for confusing Tim Ely’s Riley Ulster Imp which ran at Charterhouse with his 1935 ex-Dobson/Nancy Binns’ T.T. Sprite. A.R. Quinn, Vic Horsman’s mechanic and side-car passenger of Brooklands’ days, died in February, aged 65.