Did W.O. Bentley Crib?

An Inditement by Alec Ulmann of America

Alec Ulmann is a brave man! In the March-April issue of The Bulb Horn, official journal of the Veteran Motor Car Club of America, he dares to suggest, in an article he calls “The W. O. Bentley Enigma,” that Walter Bentley did not design the 3-litre Bentley engine but copied it from a pre-war Hispano-Suiza.

Ulmann knows full well the seriousness of his accusation, saying that on his next visit to England he may well be thrown to the vultures, for he realises that his mis-belief, publicly expressed, is equivalent to casting aspersions on the Royal Family or expressing a preference for baseball as compared to cricket.

As I appreciate Ulmann’s courage, and as he says that, being a one-time Red Label owner, he hopes his self-termed meagre evidence is wide of the mark, I would like to expand the theme a little.

Ulmann opens by remarking on the “almost total absence” of British-made high-performance cars prior to the outbreak of war in 1914. Someone should remind him of the 30/98 Vauxhall, Shelsley Crossley, 30/35, 60 and 90 Napiers, London-Edinburgh Rolls-Royce and a few others. To bring in his Hispano-Suiza he quotes six wins at Brooklands at the 1914 B.A.R.C. Whitsun Meeting by Alfonso XIII models, which, he tells us, The Motor reported as able to do 90 m.p.h. on the Track when in proper tune. To this I will merely reply that those Brooklands Bank Holiday races were handicaps and didn’t mean very much; that the fastest official lap time by an Alfonso Hispano-Suiza I can trace is 81.51 m.p.h., which could quite possibly mean 90 on the faster parts of the course. The “Alfonso” was a splendid motor car. I know, for I have owned one. But it had a T-head side-valve engine and is nothing like a 3-litre Bentley.

However, Ulmann moves on to the rare single-overhead-camshaft de luxe Hispano-Suiza of 1914, of which he suggests few cognoscenti of Hispano are aware—although all this was discussed in some detail by Kent Karslake when he wrote his Hispano-Suiza history for Motor Sport in 1950. Ulmann describes this engine as having an o.h. camshaft operating valves inclined at 30º.

He then comes to a pen-picture of W. O. Bentley, as “engaged during the 1914 War in building, presumably under licence to Gnome-Le Rhone, or Clerget, rotary-radial aircraft engines for the R.F.C. and the Allies, known as BR-1 and BR-2.” Ulmann says he refers to this merely to suggest that, in contrast to Hispano-Suiza, Rolls-Royce, Napier and Packard-Liberty, Mr. Bentley “was concentrating on what soon became an obsolete air-cooled rotary engine,” so that, unlike Birkigt of Hispano-Suiza, who adapted war-time aviation engine practice to his 37.2-h.p. car, “W. O. had no choice but to start from scratch or borrow from others.”

Now this is where too little knowledge has led the American somewhat astray. Bentley did not evolve his BR-1 and BR-2 rotary aero-engines under licence to Gnome, Le Rhone or Clerget. If Ulmann had read, or perhaps I should say checked on, W. O. Bentley’s autobiography (Faber & Faber, 1958), he would have discovered, or remembered, that Bentley did not build aero-engines; he designed them and they were built by Gwynne, Humber, Daimler, Crossley, etc. He did not pay royalties to Clerget or to anyone else, but admits he copied the Clerget valve gear for ease of production in our war-time factories, when hurriedly evolving the BR-1. When the Clerget rotary had a life of only about 15 hours on active service in the R.F.C., Bentley was encouraged by the Admiralty to design his own version of rotary engine, for which the final order was for 30,000. After the Armistice, W. O. was awarded a tax-free £8,000 for the BR-1 and BR-2 designs, although they were conceived when he was a serving officer in the R.F.C. So much for Ulmann’s sneers at that period of Bentley’s career. Certainly vee and in-line water-cooled engines soon ousted the air-cooled rotary, but it wasn’t long before air-cooled radial engines again ruled the air. . . .

Alec Ulmann also summarily disposes of Bentley’s pre-war activities with the French D.F.P. car, saying “I am told they made modifications to the engine” but hiding from his American readers the account of how W. O. pioneered the aluminium piston which, unless Bentley and his biographer Richard Hough are deliberate liars, was adopted for Rolls-Royce, Sunbeam and Gwynne-Clerget aero-engines in the early days of the war.

But Ulmann’s trump card concerns the origin of the 3-litre Bentley engine. “Mr. Bentley and his associates and financial backers were able to design, construct and exhibit at the Olympia Motor Show in London in 1919 the now famous 3-litre 4-cylinder 80 x 149 mm. prototype known as Number Ex.I,” says Ulmann, emphasising the very short span of one year. In fact, W. O. himself makes it shorter than that, giving the starting date for design as January 20th, 1919, and the Show that year opening on November 7th. However, that first prototype Bentley was constructed largely of proprietary parts and, as exhibited, had a wooden crankcase and cambox and no valve gear! However, a road-test car was available to the Press after 367 days. But it wasn’t until September 15th, 1921, that the first production model was ready.

What Ulmann is asking is how so much design and construction was compressed into such a short space of time. He implies that Bentley must have had drawings of the 90 x 150 mm. o.h.c. Hispano-Suiza engine and copied this in all essentials, even to 30º valve angle, a single magneto on the o/s. opposite the water pump, single carburetter, main-bearing bolts and cylinder-block holding-down studs. Bentley, it is true, used four valves per cylinder, based on the war-time Mercedes aero-engines, suggests Ulmann. He even remarks that the radiator and body of Ex.I remind him of an Alfonso Hispano-Suiza.

Ulmann concludes by saying he looks forward to explanations that will dispel his doubts and bring him back into the Bentley fold. Well, just because one car has been copied from another is no cause for undue surprise, it has happened so often, so our American friend has no need to feel he must turn his back on the Bentley image.

His argument is convincing, up to a point. It implies that, having Hispano-Suiza drawings to hand, the only original design work was on the cylinder head. The Hispano-Suiza engine had tubular con.-rods, whereas W. O. used I-section rods, but that could have been a post-Armistice supply expediency. I think there is another difference, namely that W. O. used a bevel-gear vertical shaft to drive his o.h. camshaft and no fan, whereas Birkigt used an offset shaft with skew gears driving the camshaft and a cooling fan.

With his inditement in The Bulb Horn Mr. Ulmann includes two sectional drawings of the engines he is comparing, which I take the liberty of reproducing, although I do not think the Bentley drawing is of Ex.I, while Mr. Karslake remarked (Motor Sport, October 1950) that the Hispano-Suiza drawing’s measurements do not correspond with the dimensions of the de luxe engines referred to by Mr. Ulmann, being more likely of the Type 8 70 x 12.0 mm. engine—not that this in any way undermines the Ulmann argument. But more detailed drawings of the engine of Ex.I and the 90 x 150 mm. engines would be needed before a direct comparison could be made—on the face of it, regarding those submitted by Ulmann, W. O. certainly didn’t copy every aspect of the latter; look, for example, at the sump arrangements.

If I had set out to denigrate W. O. Bentley’s design, I would first have wondered how Hispano-Suiza detail drawings came into his possession. His design team consisted of Harry Varley, F. T. Burgess and Clive Gallop. Gallop showed some interest in early Hispano-Suiza engines when controversy arose over Karslake’s articles in this journal but, unless he was deliberately boxing very cleverly, did not appear to have intimate knowledge of them—in any case, he joined Bentley after the prototype had been built. Varley I cannot vouch for. Burgess had been responsible for the 1914 T.T. Humbers, the engines of which so closely resembled those of the G.P. Peugeots that when Wallbank found one in the late ‘twenties it was sold to him as a Peugeot and only the inlet manifolding being on the opposite side prevented it being entered as such at Brooklands. This was an 82 x 156 mm. twin o.h.c. engine with gear train driving the camshafts, the valves at 45º. So Burgess can hardly be accused of handing W. O. his 1934 design on a plate, although Kenneth Neve, who still races one of these Humbers, has told (Motor Sport, January 1942) of chassis similarities with a 3-litre Bentley.

Having found no evidence of a direct crib of the Burgess Humber I prefer to suggest that W. O. was influenced by pre-war racing-car design but prepared drawings to his own ideas and requirements. As Bentley himself, on p. 92 of his autobiography, admits, he had the twin-cam 3-litre Peugeot and the victorious 1914 G.P. Mercedes very much in mind when planning his post-Armistice sports car, that seems a fair evaluation. In 1914 the twin o.h.c. engine did not entirely dominate the Grand Prix for the Mercedes which finished 1, 2, 3, the Opels, the Nazzaros and the Nagants all had single o.h. camshaft engines. I have no space, nor the inclination, to discuss which of these W. O. Bentley may have covered with tracing paper on his drawing-board except to remark that these were 4½-litre engines, that the Opels had the vertical-camshaft-drive shaft at the rear, as did the Mercedes, which had separate steel cylinders with welded-up water jackets copied, if you like, by Straker-Squire after the Armistice, and a 60º valve angle. . . . That he cribbed directly from Birkigt is as improbable as saying that the 3-litre Bentley was, in fact, a scaled-down Mercedes, Opel or Nagant. Unless, that is, Ulmann has something up his sleeves.

If he hasn’t, what shall we do, draw and quarter him ?—W. B.