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Professionally recreated, this is a real blueprint - made directly from a vellum master - Measuring a generous 42"x 30".
Rolls Royce Merlin Mk.61
We have all three of the Merlin series Blueprints. This blueprint is the Rolls Royce Merlin Mk.61
(Merlin Mk.61: Two-stage, two-speed gearbox series)
History of the Merlin series engines: The Rolls-Royce Merlin is a British, liquid-cooled, 27-litre (1,650 cu in)
capacity, V-12 piston aero engine, designed and built by Rolls-Royce Limited.
Initially known as the PV-12, Rolls-Royce named the
 ← Acknowledgements and Bibliography
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Continued from above... Rolls-Royce named the engine the Merlin following
the company convention of naming its piston aero engines after birds of prey.
The Rolls Royce or Packard
built Rolls Royce Merlin is one of the finest piston engines ever conceived.
Employing technology fifty years ahead of its time, the Merlin engine is a true
fighter thoroughbred.
The Rolls-Royce Merlin was developed in various steps.
In the 1920's, Rolls-Royce oversaw the development of the 'R' engine, which
evolved from both the Kestral and then Buzzard (Rolls-Royce utilized names of
birds for their engines) to spur Britain's entry into the International
Schneider Trophy seaplane contest. In 1931, the engine set a new world's speed
record of over 400mph over water, and then over land. More importantly, as later
events were about to prove, this design experience gave Rolls-Royce the
technological basis to develop the Merlin.
By 1932, it was obvious that the 745hp "Kestrel" engine, that had thus far been
a bestseller, was coming to the end of its developmental life. Sir Henry Royce,
about one year before his death in 1933, made a decision to develop a new engine
using some of the experience of the Schneider Trophy winning 'R' engine. This
new engine was initially known as the PV12 (private venture), and was entirely
funded by Rolls-Royce up to that point. However, in 1933, the British Air
Ministry agreed to finance the development of this engine, which was then termed
the "Merlin."
In 1940, when Britain was at her knees in an air war with Germany,
that determined whether Germany would invade, the mighty Merlin powered
the Spitfires and Hurricanes in the "Battle of Britain" that thwarted
the enemy's attempt. Being in strong need of aircraft, Britain employed
America to build her a plane. The P-40 was requested, but production
wasn't adequate, so James H. "Dutch" Kindleberger of North American
Aviation, built the all-new P-51A, powered by an Allison. After limited
success due to limited altitude, the P-51B received the V-1650-3 Merlin,
and subsequent models (P-51C-K) received the V-1650-7 model.
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Ironically enough, in spite of its later reputation of
extreme performance, the project was riddled with problems. After many
developments, which entail the A-G Merlins, the G model, which was
termed "Merlin II," became a successful engine after having had passed
testing. This Merlin II, with modification for high output, notably
attempted a speed record in 1937, while installed in a Supermarine
Spitfire.
In 1935, after many difficulties with the supercharger gearing
(supercharger being mechanically driven while a turbocharger is exhaust
driven), Rolls-Royce took out a license to utilize the Farman two-speed
drive. Sir Stanley Hooker, a mathematician, then developed this system
to increase performance at higher altitudes. This version became known
as the Merlin XX and was used in the British Beaufighter, Defiant,
Halifax, Hurricane, Lancaster planes and others. |
| Developmental lines: As the Merlin evolved so too did the supercharger; the latter fitting into
three broad categories:
- Single-stage, single-speed gearbox: Merlin I to III, XII, 30, 40, and 50
series
- Single-stage, two-speed gearbox: Merlin X, Merlin XX
- Two-stage, two-speed gearbox with intercooler: mainly Merlin 60, 70, and
80 series
Most of the Merlin's technical improvements resulted from more efficient
superchargers and fuel with increased octane ratings. |
Supercharger design was the real key to the Merlin performance.
A two-speed/two-stage design with tolerances measured in millionths of
an inch. What the supercharger did was keep atmospheric pressure inside
the induction system equal to sea level pressure. It did this so much
better than the Allison design that a Merlin developed more horsepower
at 26,000ft than an Allison did in full power setting for take-offs! The
problems with such a system are in cooling the fuel-air mixture, which
has been heated by the compression of the supercharger, before it gets
to the cylinder. A cooler fuel-air mixture results in a denser mixture
in the cylinder, which results in more power. Cooling of the mixture was
done through use of an 'intercooler' passage between the first and
second stages of the supercharger, and an after-cooler between the
blower outlet and the intake manifold.
- Be sure to visit our aircraft sounds page (Historic Archive •
Vault) and listen to the powerful P-51 mustang engine...
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The Merlin was used on
numerous aircraft including: |
| Hawker
Hurricane |
Beaufighter
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| P-51 Mustang
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Hotspur
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| Supermarine
Spitfire |
Defiant
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| F-82 Twin
Mustang |
Barracuda
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| Mosquito
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Hornet |
| Wellington
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Whitley
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| Fulmar |
Canadair 4 |
| Miles M.20 |
Lincoln |
| Battle
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Kittyhawk
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| Halifax
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Athena
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| Tudor
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Balliol
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| Cierva Air
Horse |
York
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| Lancaster
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Henley
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Further development produced the first American built
Merlin (done under license by the Packard Motorcar Company of
Detroit), the V-1650-1, which was used in the P-40F model. P-40's had
used the dependable Allison engine that utilized a turbocharger,
however, GE could not meet production demands of equipping both bombers
and fighters with turbochargers, so most Allison powered planes were
limited by altitude. Such was the case with most P-40's, and the initial
P-51A.
The idea of a marriage of the P-51 mustang airframe and the Rolls Royce
Merlin engine began long before anyone had ever heard of a Mustang. And,
contrary to popular belief, this was not exclusively a British idea. Why
the Merlin? The answer to that question is simple expediency! The Rolls
Royce Merlin engine was a proven design and available at the time. It
was already powering some of the world's best warplanes - the Hurricane,
Avro Lancaster and, of course, the superb Supermarine Spitfire.
To develop a new engine for the P-51 comparable to the Merlin required
time, time the Allies simply did not have. Remember this was mid-1942
and the United States was still reeling from the Pearl Harbor attack,
Great Britain was still standing alone opposite an entirely hostile
continent and Soviet Russia was still retreating before the Nazi
Blitzkrieg. The Allies needed weapons to fight the tide of defeat and
they needed them right away! One of those weapons would be the
Merlin-powered Mustang.
The mighty Merlin, with its extremely good supercharger, gave the
Mustang the ability to perform well up to 41,900 feet achieving the
speed of 437mph. This combination of engine and plane, produced the
winning superior allied fighter of WWII.
During the war there was enormous pressure to develop the capacity of
the piston engine. The Merlin typified the trend, more than doubling in
power from 746 kW (1000 hp) in 1939 to over 1567 kW (2100 hp) by 1944,
mainly through improvements in supercharging. |
Summary:
The first operational aircraft to enter service using the Merlin were the
Fairey Battle, Hawker Hurricane and Supermarine Spitfire. More Merlins were made
for the four-engined Avro Lancaster heavy bomber than any other aircraft;
however, the engine is most closely associated with the Spitfire and P-51
Mustang. An English Icon, the Merlin was one of the most successful aircraft
engines of World War II.The V-1650 liquid-cooled Packard engine was the U.S. version of the
famous British Rolls-Royce "Merlin" engine which powered the "Spitfire"
and "Hurricane" fighters during the Battle of Britain in 1940. In Sept.
1940, the Packard Co. agreed to build the Merlin engine for both the
American and the British Governments, and adapted it for American
mass-production methods. The first two Packard-built Merlins to be
completed were demonstrated on test stands at a special ceremony at the
Packard plant in Detroit on August 2, 1941.
Full production began in 1942 and by the end of World War II, 55,873
Merlin engines had been produced in the U.S.A. The Army Air Forces used
the Merlin engine almost exclusively in the famed P-51 "Mustang", for it
provided greatly improved high-altitude performance over the Allison
V-1710 engine used in earlier series of the airplane. The V-1650 Merlin
also replaced the V-1710 in the "F" series of the P-40. The British also
used Packard-built Merlins during the last three years of the war in
their "Spitfire", "Mosquito", and "Lancaster" airplanes.
Most of the Merlin's technical improvements resulted from more efficient
superchargers and fuel with increased octane ratings.
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