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The Merlin: How Rolls-Royce Teamed up with Packard to Help End World War 2

Workers at the Rolls-Royce factory assemble the V12 Merlin aircraft engine in 1942. (Image: A Merlin Is Made- the Production of Merlin Engines at a Rolls Royce Factory, 1942 by Richard Stone)

If you asked a military historian to name the five most important Allied fighter planes of World War II, you can bet they’d include the North American P-51 Mustang and Supermarine Spitfire on the list.

Those two aircraft were common sights in the skies above the European Theatre, as they were adapted to a range of pursuit, bomber, escort, and reconnaissance roles.

And interestingly enough, both planes shared variations of the same powerplant: the 27 liter, supercharged Rolls-Royce Merlin V12.

Given the Merlin’s British origins, the engine found its way into plenty of other aircraft in the Royal Air Force as well, namely the Hawker Hurricane and de Havilland Mosquito fighter planes, along with the Avro Lancaster heavy bomber. But Merlins also wound up in American planes beside the P-51, like the Curtiss P-40 Kittyhawk.

With its signature elliptical wings, many consider the Spitfire one of the most beautiful airplanes ever made. And thanks to the Merlin, it sounds pretty good too. (Image: Restored Spitfire CGYQQ Y2K S/N TE294, in the air over Comox BC Canada by Guiness323 | CC BY-SA 4.0)

Meet the Merlin

For starters, the Merlin wasn’t Rolls-Royce’s first foray into aircraft propulsion. It evolved out of a program to improve upon the company’s V12 Kestrel engine originally designed in the 1920s. As with a lot of military development programs, the design started with some established performance goals, specifically an airplane that can maintain a minimum airspeed above 310 mph. After a few years of development, testing, and refinement, the Merlin entered service in 1936 in a British Fairey Battle light bomber.

So what made the Merlin engine so special?

Most experts would probably say its supercharger. In addition to increasing the engine’s overall power output, forced air induction was central to the Merlin’s ability to perform at high altitude. As the Merlin continued to evolve throughout the wartime years, improvements to the supercharger system played a big role in its increased performance and versatility.

Here, workers install the Merlin’s supercharger assembly at the back of the engine sometime around 1942. (Image: A Merlin Is Made- the Production of Merlin Engines at a Rolls Royce Factory, 1942 by Richard Stone)

While the original prototype Merlins made around 700 horsepower, that number was over 1,000 by the time the Merlin entered production in 1936. Near the end of the war in 1945, most Merlins were making closer to 1,800 horsepower. And in certain configurations, in specialized high-boost environments, running high-octane fuels, Merlins could be tuned north of 2,000 horsepower.

Packard Lends a Hand

As the RAF began to realize the Merlin’s potential, word of its capabilities quickly spread across the pond.

The United States wanted some Merlin magic too.

Problem was, Rolls-Royce was already cranking out as many Merlins as it could, and all those engines were quickly snapped up by British aircraft manufacturers eager to get their planes out to the Eastern Front. Besides, with U-boat Wolf Packs patrolling the North Atlantic shipping lanes, the threat of sunken cargo vessels full of new Merlins was daunting.

Thankfully, the beleaguered British were happy to license the Merlin to an American company in an effort to get more Allied airplanes into the skies above Europe. The Packard Automobile Company stepped up to the plate with its factories and manufacturing capabilities.

The P-51 Mustang can credit its signature engine snarl to the Merlin. (Image: P-51 Airplane by Crefollet | CC0 1.0)

The Packard Merlin was dubbed V-1650 and it closely mirrored the Rolls-Royce Merlin evolution, as continually updated versions left the Packard factory while the war raged on. While most of the Rolls-Royce Merlins found homes in British aircraft, the Packard Merlin became the powerplant of choice for the North American P-51 Mustang.

The Rolls-Royce Merlin Legacy

As alluded to above, the Rolls-Royce and Packard Merlins were the go-to powerplants for two of the most prominent Allied fighters of World War II: the Supermarine Spitfire and North American P-51 Mustang.

These planes helped fight back the German Luftwaffe and turn the tide of the war in the European Theatre.

Merlin-powered Hurricanes and Spitfires thwarted the German advance in the Battle of Britain, while P-51 Mustangs escorted long-range heavy bombers like the B-17 during the pivotal daylight bombing campaigns that accelerated the end of the war in Europe.

While credit certainly goes to the brave men and women who fought in and alongside these aircraft, the engineers, mechanics, and designers behind the Merlin engine deserve heartfelt recognition as well.

One More Thing….

Want to hear what four Merlins sound like when powering a 36,000-pound Avro Lancaster heavy bomber?

Of course you do. Check it out below:

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  1. You may not know but RR and Packard go back futher then the Merlin.
    RR licensed the front suspension system from Packard in the early 30’s and used it untill the 50’s.
    That is why the RR’s had such a smooth ride.
    Just a side note.

  2. John Lovins says:

    They were also the go to engine in Hydroplane racing (Watch the movie ‘Madison” sometime.) until the Turbines took over. A few are still used in Tractor pulling.

    • Whoa–I had no idea. Bet those races sounded incredible. And never heard of that movie before, but I’ll watch anything with Bruce Dern in it. Thanks for the heads up. Here’s the trailer if anyone else is interested. It’s currently Free (w/Ads) on YouTube. Good soundtrack too.

  3. Stephen R Bierce says:

    Last year I did a lot of research into the Canadian-built Hawker Hurricanes. Circumstantial evidence suggests that when the planes arrived in the UK (shipped rather than ferried, since they didn’t have the range to cross the ocean), the technical units pulled the Packard Merlins off the airframes and put Rolls-Royce engines in instead before issuing the planes to their destined combat squadrons. Bomber Command needed the Packards for the Lancasters.

  4. Pingback: Ask Away! with Jeff Smith: What Does "Inches of Mercury" Mean & How Does It Measure Vacuum?

  5. Glenn V falzo says:

    I heard there is a book on the Packard Built Merlin, I can’t seem to find it, ANY help would be appreciated.
    Thank You

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