If you’ve ever watched a documentary about the Second World War or seen a classic film such as The Dambusters, you will be familiar with the Merlin engine’s throaty sound. Inspired by the R-engine that won the Scheider trophy Rolls Royce and then Packard further developed the engine. It was instrumental in winning the war and achieved legendary status among fans online with a physicaladdress and in the world of aviation engineering.
History of Merlin engine
The Merlin engine was first run on October 15th, 1933, and passed its type test in July 1934. It generated 790 hp and took flight in February 1935. Initially developed by Rolls Royce, it was called the Kestrel engine at first and was based around the R engine, which won the Schneider Trophy. Rolls-Royce had a tradition of naming their engines after birds of prey, and the newly developed engine was named Merlin.
Coinciding with the outbreak of the war, the Merlin engine powered the remarkable Supermarine Spitfire. Most people associate the Merlin engine with this legendary aircraft. It powered around 40 aircraft in the RAF, including the Hawker Hurricane, the Lancaster bomber, and the De Havilland Mosquito. In 1950 production of the Merlin engine came to an end with around 150,000 having been made. The engine is still used in the Battle of Britain memorial Flights.
Learn more about Radial engines used in aircrafts during World War II
Learn more about Internal Combustion Engines here.
The Merlin engine was a 12 cylinder engine consisting of high carbon-steel liners. The cylinders were set in two blocks of aluminum alloy with separate heads and skirts; the cylinder heads were fitted with cast-iron inlet valve guides and bronze exhaust valve guides.
Its pistons were machined from alloy forgings and functioned with three compression rings and one oil-control ring. The crankshaft was manufactured from nitrogen hardened nickel-chrome steel and featured seven main bearings and six throws.
The engine’s spec changed considerably over time with technical improvements in the form of more efficient superchargers and high-octane aviation fuels. By the end of the war, the fuel was being delivered at a 150-octane rating allowing the Merlin engine to reach as much as 2000hp(twice that of today’s Bugatti Veyron) !
- Type – 12-cylinder, supercharged, liquid-cooled, 60° “V”, piston aircraft engine.
- Bore – 137 mm
- Stroke – 152 mm
- Displacement – 27 L
- Length – 2.25 m
- Width – 0.78 m
- Height – 1m
- Dry weight: 744 kg
- Compression ratio – 6:1
- Power-to-weight ratio – 1.5kW/kg at max power output
Weaknesses of the Merlin Engine
When it was first introduced, the Merlin engine had issues with leaking coolant and cylinder heads that frequently cracked. These issues, however, were all ironed out by version F in 1936. The Merline Mark I arrived in 1937, ready for service, and was improved continuously from then on. One notable early weakness of the engine was the lack of power generated by the supercharger, particularly at low altitudes. Sir Stanley Hooker solved the problem, and the Merlin XX was born. His improvements to the engine made all the difference to the Spitfire and Hurricane during the Battle of Britain, which was mostly fought below 6000ft.
Following the end of the war, the Merlin engine could still be heard above London each Victory day in the form of a Spitfire and Hurricane. The tradition continued annually and soon became the Battle of Britain Memorial Flight. The Merlin Engine was decommissioned in 1950, signaling a new era in aircraft engineering, an era of more efficient, powerful and smoother engines – jet engines. However, for those who still want to hear the throttle of the classic Merlin engine, they can do so at the annual Battle of Britain Memorial Flights.
Well, talking about Merlin engines… does it remind of you something else? Well, it does make me – of super-powerful SpaceX rocket engines. Yup.. we will talk about them in another article, another day 😉