From the earliest days of warfare, it’s never been enough to be able to build a deadlier weapon than your enemy can. Making a sharper spear, an arrow that flies farther and straighter, or a more accurate rifle are all important, but if you can’t make a lot of those spears, arrows, or guns, their quality doesn’t matter. As the saying goes, quantity has a quality of its own.
That was the problem faced by Britain in the run-up to World War II. In the 1930s, Rolls-Royce had developed one of the finest pieces of engineering ever conceived: the Merlin engine. Planners knew they had something special in the supercharged V-12 engine, which would go on to power fighters such as the Supermarine Spitfire, and bombers like the Avro Lancaster and Hawker Hurricane. But, the engine would be needed in such numbers that an entire system would need to be built to produce enough of them to make a difference.
“Contribution to Victory,” a film that appears to date from the early 1950s, documents the expansive efforts of the Rolls-Royce corporation to ramp up Merlin engine production for World War II. Compiled from footage shot during the mid to late 1930s, the film details not just the exquisite mechanical engineering of the Merlin but how a web of enterprises was brought together under one vast, vertically integrated umbrella. Designing the engine and the infrastructure to produce it in massive numbers took place in parallel, which must have represented a huge gamble for Rolls-Royce and the Air Ministry. To manage that risk, Rolls-Royce designers made wooden scale models on the Merlin, to test fitment and look for potential interference problems before any castings were made or metal was cut. They also set up an experimental shop dedicated to looking at the processes of making each part, and how human factors could be streamlined to make it easier to manufacture the engines.
With prototype engines and processes in hand, Rolls-Royce embarked on a massive scale-up to production levels. They built huge plants in Crewe and Glasgow, hopefully as far from the Luftwaffe’s reach as possible. They also undertook a massive social engineering effort, building a network of training institutions tasked with churning out the millions of skilled workers needed. Entire towns were constructed to house the workers, and each factory had its own support services, including fire brigade and medical departments.
As fascinating as the engineering behind the engineering is, the film is still a love letter to the engine itself, of which almost 150,000 copies would eventually be manufactured. The casting processes are perhaps the most interesting, but there’s eye candy aplenty for Merlin fans at every stage of production. We were also surprised to learn that Rolls-Royce took the added step of mounting finished Merlins in the cowlings needed for the various planes they were destined for, to ensure that the engine would be properly integrated with the airframe. This must have been a huge boon to groundcrews out in the field; being able to bolt a new nose on a Spitfire and get it back in the fight with a spanking new Merlin was probably key to victory in the Battle of Britain.
The Hawker Hurricane was a fighter, not a bomber.
The REAL boost in the war was when a guy from Rolls-Royce got a ride in a P-51 Mustang and said “this plane would be even better if we put a Merlin engine in it” (the result was the P-51D Mustang, one of the best propellor driven fighter planes ever made)
Yeah, because up to that point, nothing had happened….
The first production Mustang to fly with Merlin engine was the P-51B – first flight in may 1943.
The P-51D was a latter model (nov 1943), also with the Merlin engine. It was fitted with the “Tear Drop” canopy which greatly improved the rear visibility and made it the best WWII fighter.
second best after the Mosquito.
Why the Mosquito isn’t mentioned above baffles me…
Mosquito was a bomber…
Interesting find. Funnily enough just as I started to read this we had one of the local Spitfires doing some aerobatics almost directly overhead. Just a fantastic sound of the Merlin. This is Dorset in the UK.
Technical details:
https://en.wikipedia.org/wiki/Rolls-Royce_Merlin
I’m fortunate enough to live near RAF Duxford and regularly see the spitfires, hurricanes and occasionally the Lancaster of the battle of Britain flight. It’s regular enough that I can recognise the sound of a merlin engine in the office and know to go outside and watch the show!
Me too!
I used to live on the flightpath to RAF Watton in the fifties one mile to the runway as the crow flies. We had among other aircraft lots of Lincolns flying at all hours going over. The closer they got the faster the tv screen would roll. I love the sound of those engines growling over us, waving to the pilots as they went over. Phil.
I remember an engineering joke?true tale? whereby the English engineers took a look at an American fighter plane engine and said what utter garbage with 0.050” bearing clearances -we can tighten them up to 0.005” and so they did exceptall the planes started getting shot out of the air because turns out the super large tolerances were to ensure extra minutes of run time for the engines in case the oil line got shot thru and the engines lost oil pressure especially as compared to the german planes after losing oil pressure and the large tolerances gave you like 3-5 minutes extra run time til the engine seized.
but now of course I can’t seem to verify this anywhere on the internet. but that’s ok too
I still think it’s a funny anecdote
sounds similar to a story I heard about the XB-70… stuff was being built for that test bomber at specifications that were higher than clearance tolerance just 10-15 years before.
Well, it is “easy” to design with ultra tight (and ultra expensive) tolerances and get a working design that is then very difficult to built in quantity. The greater merit is in understanding which areas of a product require the ultra precission parts and which can do with more normal components.
The article is missing a key point – Rolls Royce was unable to produce the engines fast enough to keep up with demand. They subcontracted out to Ford. Ford looked at the blueprints and said “the tolerances don’t need to be this tight.” Rolls waffled for a bit, but Ford ended up redoing the engineering of the engine, making it much faster to produce while also making it more reliable. Even up saving the entire Merlin program.
That’s not quite accurate. Prewar, RR produced to wide tolerances, and parts were fitted by experienced mechanics who would measure the parts and select parts that would combine to give a good fit, also modifying parts if necessary.
To scale up production, they had to tighten up tolerances so that any part would fit. The usual story is that this was done by Ford or Packard, but in fact this was done by RR when they had to scale up production and set up shadow factories.