The Rolls-Royce Merlin Aero Engine
Appendix 1 — The British Air Ministry and the "Dragonfly Decision"
by Jerry Wells

The Major and WWI

Given that all aero-engine development in Great Britain was funded by the tax payer, the role of the relevant government ministry in dispensing and supervising the considerable sums involved deserves some consideration. In general, the public perception of government department employees is one of faceless bureaucrats and anonymous civil and public servants. However, in the case of the British Air Ministry's engine department in the decade preceding WWII, a detailed insight has become available in the form of the published memoirs of the particular public servant who was in charge of the pre-WWII aircraft engine programme.

George Purvis Bulman (1892 - 1979) had completed a four year engineering diploma in early 1914 and, at the outbreak of war, was seconded to the Aeronautical Inspection Department where he worked as an inspector, finishing the war with the rank of major. Being personally and actively involved with all aspects of aero-engine maintenance and operation during the years of conflict, he also finished the war with a wealth of experience.

In the post-war period, Bulman, now a civilian, remained with the aero-engine section of the Air Ministry and in 1928 was deservedly, appointed to the top job, a position he held until 1943. As far as the authorisation and funding of engine projects from any manufacturer was concerned, Bulman's approval was crucial.

Bulman and the Dragonfly

Towards the end of WWI, Bulman (a senior AID inspector), recounts how he was sent to the All British Co. (A.B.C) factory located at Walton-On-Thames (SW London) to examine the prototype 7-cylinder Wasp radial. His subsequent report concluded that, with development, the engine had some potential.

The 9-cylinder evolution of the Wasp, named Dragonfly, was sold to the war department by its designer Granville Bradshaw, even though it was still an "on paper" design. The then Air Minister, William Douglas Weir was so impressed with the Dragonfly that he ordered 10,000 examples of the engine to be produced.

In his memoirs, Bulman says that he was horrified when he learned of the decision to put the engine into production without a planned and thorough development period.

The problems that beset the Dragonfly have been well documented — such was the magnitude of these troubles that the engine never went into full scale production. Bulman concludes, " was a hideous episode illustrating the effect of a single, unwise decision based on ‘cleverness’ and (it) should never be forgotten by any future arbiter of high responsibility."

Bulman and Ramp Head Merlin

However, in 1928, as far as ordering aero-engines into production in Great Britain, the aforementioned "arbiter of high responsibility" was, at that point in time, none other than George Purvis Bulman and his decision to authorise Rolls-Royce to put the ramp-head Merlin F into production as the Merlin Mk 1 was, in principle, no different to the Dragonfly episode of 1918. In his memoirs, he is scathing in his criticism of the decision to begin the manufacture of the ABC engine before a proper testing programme had been done, yet in 1937, 170 Merlin Mk 1 engines were authorised without the prototypes having passed the standard 100 hour type-test requirements. This was a staggering decision given the status of the Merlin engine, i.e., this power plant was created, from the drawing board, as a military combat aircraft engine designed primarily for air superiority fighters. It had to be tough and reliable.

His final words regarding the Dragonfly read, "Had the war dragged on into 1919, the Dragonfly would have lost it for us in the air." It is interesting to speculate what might have happened "in the air" if the entire Spitfire and Hurricane force had entered the Battle of Britain fitted with Merlin Mk 1 engines instead of the (slightly) more reliable Kestrel Major (Merlin Mk 2) motors. The unavailability of fighter aircraft due to defunct engines could have reached alarming proportions.

Bulman and Rolls-Royce

In England throughout the 1930s, four engine manufacturers were patronised by the Air Ministry, vis Armstrong-Siddeley, Bristol, Napier and Rolls-Royce.

One of Bulman's first decisions as Head of Engines was that he would maintain a close, personal relationship with these companies, i.e., to adopt the so-called "hands-on" approach. To achieve this he made a point of visiting each firm once a month in order to observe and discuss, first hand, the progress and development being made.

From his descriptions of these visits, it is hard not to conclude that Bulman's relationship with Rolls-Royce was "cosy" to put it mildly. For comparison, in the case of a visit to Bristol, "I would go down to Bristol by the late afternoon train." but to Rolls-Royce, it was a matter of, "travelling up the previous evening, usually with Bill Lappin in a Rolls or Bentley (which he would let me drive)". Having arrived in Derby, Bulman would enjoy accommodation in the Company's purpose-acquired three-storey, VIP manor known as Duffield Bank House which overlooked the Derwent river. That evening, a sumptuous dinner with selected R-R executives was consumed washed down with fine wines after which games of darts or snooker were played, no doubt with best cigars, brandy, port and liqueurs to complete the enjoyment! And this little charade of indulgence occurred once a month!

It is difficult to comprehend how anyone who had just received this level of hospitality could turn up at the factory the next morning and tell the Chief Engineer that his ramp-head design was a failure or the Managing Director that the development period for the Merlin was taking far too long.

It is all very well to be "hands-on" but there is also a lot to be said for also being at "arms-length"!

Bulman's Darkest Hour

As a member of the aero-engine inspectorate in 1918, who had witnessed at close quarters the catastrophic results that stemmed from the premature manufacture of such engines as the Sunbeam Arab and the A.B.C. Dragonfly, it hardly needs saying that his decision to allow the ramp-head Merlin to be series produced in 1937 was so contrary to everything he had observed, experienced and learned during more than two decades of continuous work in the aero-engine business, that it beggars belief.

The decision could only have been made due to enormous pressure on Bulman from the circumstances pertaining at the time.

These pressures were the result of a series of events which started shortly after Bulman's appointment to the Head of Engines position in 1928.

Event 1 was the Schneider Trophy contests of 1929 and 1931. Bulman claims the decision to use Rolls-Royce as the engine supplier to Supermarines instead of Napiers was his and, given the success achieved in both contests it is no surprise that Bulman saw Rolls-Royce as England's premier designers and builders of high power aircraft engines for all future military requirements.

Event 2 was the R-R PV-12 engine, the parameters for which Henry Royce laid down in the last year of his life. Bulman had no hesitation in providing all the financial backing asked for regarding the development of the Merlin — at that stage he had complete confidence in R-R and, knowing that the "R" engine had delivered 64 HP/litre whereas the Merlin was aimed at producing a modest 37 HP/litre, it seemed to him, quite understandably, that the Merlin as a sound, military engine, would be an easy project for the R-R team to undertake.

Event 3 was the death of Henry Royce in 1933 followed closely by the derailing of the Merlin project by Elliott and Pearson per medium of the introduction of the ramp-head cylinder head design to the prototype engines. From this point on, Bulman was let down very badly by the R-R team. The early Merlins performed abysmally and valuable time was eaten up.

Event 4 was the deteriorating political situation in Europe. Bulman visited Germany in 1937 and came back knowing that he needed Merlin engines in production numbers not temperamental prototypes. And he needed them quickly.

Thus, at this point in time (1937) Bulman was inextricably caught between the proverbial "rock and a hard place" — the "rock" being ten or so sub-standard ramp-head Merlins and the "hard place" being the threat of war with Germany. The pressures were too great. Bulman, against all his better judgement ordered the unqualified Merlin into production. "Those who ignore the lessons of history are doomed to repeat them." — George Santayana (1863 - 1952)


An Account of Partnership - The Memoirs of George Purvis Bulman. Ed by M C Neale. Rolls-Royce Heritage Trust, 2002.