The Man who put the Merlin in the Mustang: Two Obituaries

Ronald Harker, OBE, AE, wartime test pilot, died in Taupo, New Zealand, on May 30 aged 90. He was born on March 4, 1909.

Ronnie Harker has his place in the history of aviation for the role he played in the evolution of the Mustang fighter into one of the great warplanes of its era. The P51 Mustang had originally been designed and built by North American Aviation in 1940 in answer to a request by the British Purchasing Commission to produce a fighter for the RAF which would be an advance on the Spitfire. The result, produced in the incredibly short time of 117 days, had many pleasing qualities, but its Allison V1710 engine gave it poor performance at high altitude, and its range was short.

The aircraft entered service with the RAF in 1941, but because its performance did not challenge that of the latest marks of Spitfire it was relegated to Army co-operation and photographic work. However, Ronnie Harker, Rolls-Royce's senior liaison test pilot, was offered the opportunity to test the Mustang by the RAF. He liked the aircraft's handling qualities but not its engine, which was too low-powered to exploit the aircraft's advanced aerodynamic features. He was convinced that the plane would be another animal entirely if fitted with the Rolls-Royce Merlin, powerplant of the Spitfire.

Harker pressed strongly for the American engine to be replaced by the Merlin and after a good deal of official reluctance, largely from the Air Ministry, he got his way. The result was a transformation. The Mustang's top speed leapt from 390mph to 440mph and the range from 450 miles to as much as 2,000 with various configurations of drop tanks. A great escort fighter had been born and the Americans, realising that the Rolls-Royce solution provided the answer to the horrific losses the USAAF's daylight bombing raids had been suffering in the early part of 1943, put the fighter into mass production, using Packard and Continental-built versions of the Rolls-Royce engine. Very soon the Flying Fortresses of the US 8th Army Air Force were able to rove as far as Berlin, escorted all the way by Mustangs which began to take a toll of the Luftwaffe's fighters. When Goering saw the Mustangs escorting the American air armadas over the capital of the Reich he is said to have realised that Germany had lost the war. Such was the momentousness of one man's determination. Ever afterwards Harker was known as "the man who put the Merlin in the Mustang".

Ronald Ward Harker was born at Tynemouth, where his father was chief medical officer for the Tyne ports. He was educated at Shrewsbury School and joined Rolls-Royce in 1925 as an engineering apprentice. In 1927 a visit to the Hendon Air Display gave him the impulse to fly. He joined Newcastle flying club in 1927. He finished his apprenticeship in 1929, but by that time the Depression was biting and there was no job for him at Rolls-Royce. With parental support he kept up his flying at the Lympne flying club in Kent, and in 1934 was invited back to Rolls-Royce on the aero-engine side. When Rolls-Royce formed its first test flight he became its first test pilot and was soon evaluating various types of RAF aircraft. He also joined No 504 City of Nottingham Squadron, Royal Auxiliary Air Force, based at Hucknall, where Rolls-Royce was soon to move its test flying.

When war came in 1939 he joined his squadron on a full-time basis, but in the spring of 1940, with the squadron ordered to France, he was ordered back to Rolls-Royce to resume test flying at Hucknall, liaising closely with the RAF. Harker was at Hucknall when, in April 1942, he received a telephone call from the CO of the RAF's Air Fighting Development Unit at Duxford, to tell him that they had acquired an Allison-engined Mustang and would he like to evaluate it? Having spent 30 minutes throwing the aircraft round the sky he reported that it closely resembled the Messerschmitt 109F, but with a Merlin 61 engine ought to prove much faster than that aircraft and the Spitfire V. The Air Ministry, however, wanted to put all the available Merlin 61s into the new Spitfire IX to combat the threat of the latest German fighter, the Focke Wulf 190, which was proving vastly superior to the Spitfire V in combat. There was therefore a good deal of concerted scepticism about Harker's observations. But he persisted and the first Merlin-engined Mustang flew in October 1942, giving the radical improvements in performance that he had predicted. News of the Merlin Mustang's performance spread like wildfire and was greeted as manna from heaven in Washington. Indeed, the Americans were the chief beneficiaries of Harker's initiative, since the new escort fighter enabled the USAAF to resume daylight bombing raids which had been discontinued, since the "invulnerable" B17 Flying Fortress had proved incapable of defending itself against the Luftwaffe's fighters.

Throughout the war Harker was involved in a variety of other projects for improving the performance of RAF aircraft. Improvements in superchargers increased the speed of the Spitfire; Merlins were put into the Whitley bomber; and - the greatest bomber success of all - the disastrous Vulture-engined Avro Manchester became the superlative Merlin-engined Lancaster. But the Mustang remains his supreme achievement. By the end of the war 15,582 of the aircraft had been built. Harker was appointed OBE and given the Air Efficiency Award (AE) for his wartime work. After the war Harker continued his liaison work with the RAF, testing new types. In 1974 he moved to London as Rolls-Royce's aero-export manager and from 1957 as the company's military adviser. He retired from the firm in 1971 when it went bankrupt over the financial problems caused by the escalating cost of the RB211 engine for the Lockheed TriStar. Over the years he had spent an increasing amount of time in New Zealand pursuing his passion for fishing - and flying - and he finally settled there with his second wife in 1993. He had his last flight in a Mustang in New Zealand in 1997 at the age of 88. Ronnie Harker was twice married, first to Marjorie Turner, who died in 1979. His second marriage was to Elizabeth Dove, who survives him with the two daughters of his first marriage.


RONNIE HARKER, who has died aged 90, made a signal contribution as a test pilot to Allied victory in the air during the Second World War.Ronnie Harker was born in the year Bleriot crossed the Channel from France to England, and was a seasoned pilot when the Luftwaffe came in the same direction in 1940. Though he did not see combat, his association with the Merlin aero-engine put him in the front line of preparing Spitfire and Hurricane squadrons to meet the challenge, and later in devising the Merlin-powered Mustang fighter which took the air war back to the heart of Germany.As senior test pilot for Rolls-Royce, the company that manufactured the Merlin, Harker flew between combat squadrons during the Battle of Britain, organising a flow of spare parts to keep the fighters flying. At the same time he stood ready to defend the company's experimental aerodrome at Hucknall near Nottingham from German bombers.In the technical race with Germany that followed the Battle of Britain, Harker test-piloted the Merlin 60 series engine. During the test programme a colleague was killed, but at last Harker overcame the carburetted powerplant's habit of cutting out in tight turns under negative G. The new engine powered the Spitfire IX, greatly improving the fighter's performance.

But Harker won his place in the history of aviation as "the man who put the Merlin in the Mustang". He was the first to spot the potential of the otherwise mediocre fighter that had been ordered for the RAF from North American Aviation just after the fall of France.He tested an early production Mustang on April 30 1942 at the Air Fighting Development Unit at Duxford, and reported approvingly of its fuel load - three times that of a Spitfire - and its heavy armament. Its airframe, he found, was aerodynamically advanced and manoeuvreable up to 20,000 feet, but its Allison engine was underpowered for high altitude combat.Harker knew the solution, and asked colleagues to see how the aircraft would perform with a Merlin 61. This engine was at the time being manufactured under high priority for the Spitfire IX - a fighter needed to counter the threat of the latest German Focke-Wulf 190 fighter. At first, Rolls-Royce executives were reluctant, but Harker persuaded them. Sir Wilfrid Freeman at the Air Ministry was brought round, and six weeks later the first Merlin-Mustang was test flown from Hucknall. Thus the greatest piston-engined fighter of the war was born. Harker got a pay rise of a pound a week.The Merlin-Mustang was ordered for the US Army Air Force as the P-51. Mass produced in the United States with Merlin engines and licence-built by Packard, more than 15,000 were manufactured. Drop tanks added strategic range, and from 1944 Mustangs escorted US 8th Air Force bombers with enough fuel to engage defending fighters as far as Berlin. After D-Day, Mustangs ranged over north-west Europe shooting up German transport.Ronald Ward Harker was born on March 4 1909 at Tynemouth, the son of the chief medical officer for Tyneside. He joined Rolls-Royce aged 16 from Shrewsbury School as an apprentice, enthusiastically taking up flying after visiting the 1927 Hendon Air Pageant. After Rolls was hit by the Depression he was laid off, but with the help of his father he continued to fly as a club pilot.

Harker rejoined Rolls in 1934, moving to Hucknall as its first test pilot, proving Goshawk, Kestrel and Merlin engines in a range of types. In 1938 he was instrumental in settling into service the first operational Hawker Hurricane squadron, No 111, at Northolt.On the outbreak of war, he joined No 504, County of Nottingham Squadron, serving as a flight lieutenant. But when his squadron was ordered to France in March 1940, Harker returned to Rolls.As well as the Mustang, Harker worked on re-engineering RAF bombers for the liquid-cooled, in-line Merlin. He also helped to transform the abysmal twin Vulture-powered Avro Manchester into the Lancaster, the best heavy bomber of the war.

For his wartime work Harker was appointed OBE and given the Air Efficiency award.Harker stayed with Rolls after the war, becoming a sales executive in 1947 and military aviation adviser 10 years later. On his advice the Royal Navy ordered the US F-4 Phantom fighter with Rolls-Royce Speys.He retired, reluctantly, in 1971 when the company went into receivership, crippled by the development costs of the RB211 engine. Harker became an independent aviation consultant, and made a new home in New Zealand. There in 1997, aged 88, he took the controls of a Mustang at an air display.Ronald Harker married, first, Marjorie Turner, who died in 1979, and secondly Elizabeth Dove, who survives him, with two daughters of his first marriage.

The Times of London obituary was reprinted in The Dominion of Wellington, New Zealand of 18 June 1999, under the heading "The Man who put the Merlin in the Mustang", with a photo of him taken after a flight in a Mustang in New Zealand in 1997. This is probably at the "Warbirds over Wanaka" display near Dunedin. A death notice in the New Zealand Herald (Auckland) of 3rd June 1999 said that he had died at Taupo on May 30, 1999 and that a private family service had been held at Taupo the previous day. (Taupo in the middle of the North Island of New Zealand has good trout fishing, presumably why he settled there). The OBE refered to is an award/medal not an appointment, the Order of the British Empire.



The original articles were not modified, presentation was changed. These articles were submitted by John Wilson, New Zealand. Thanks for your contribution.




    Mustang! - A Bravo Bravo Aviation website - All rights reserved © 2013