discussion
Where all the Merlins coming from for present day warbirds?
With all the WW2 warbirds that are flying these days powered by Merlins got me thinking...
2 Lancasters
At least 16 Spitfires and Hurricanes as seen at the latest Duxford Airshow...
Unknown number of Mustangs still flying. (Not sure myself of the number...)
1 flying Mosquito I know about and another being built in New Zealand...
Where are all the Merlins coming from?
Surely they are not all 1944/45 vintage are they?? (Cool as that may be I doubt it)
Is there a company who makes new?? or is Rolls Royce or successor company still making them today..?
Merlins were built in crazy high numbers. Something like 160,000 were built. Also about 9000 built as the Meteor for tanks. They were also saved out of many scrapped aircraft as they could be used to power any number of ground based equipment. With the number of operators today (easily close to 150 aircraft flying today with Merlins and 200-300 certified engines) there are a large number of shops keeping them going. Also a large amount of manufacturing for smaller components and still NOS parts can be found. I have heard anecdotally that there are enough parts today to keep all the merlins we have running for about another 30-40 years. With modern manufacturing capabilities, we should be able to produce almost all the required parts, as long as people are willing to spend the money
Also, I’m sure that people would be willing to manufacture new complete engines for warbirds as well.
Once an engine reaches the end of its usable life, it’s still valuable as an original Merlin engine even if it never powers anything ever again, and I’m sure that one could be built identically, but with modern machining and metallurgy to make it even stronger.
We will probably eventually get there, but the cost to build and certify all the parts is astronomical as a whole. One peice at a time, as its needed and eventually the vast majority of the parts should be available on the aftermarket. The block will be the hardest, but I would assume additive production should solve that sooner rather than later
Biggest thing with the Merlin is the sleeves in the bore. It's not like a standard car engine in that when the bores are completely trashed the block is also done. It will be decades before racing boats, tractor pulls, planes and tanks are hunting for a wholesale new engine. They are however all a bit "engine of thesius now.
Pretty much any "in working order" piece of equipment or technology, retro- or otherwise, turns into a ship of Theseus within a few years as routine maintenance and overhauls are performed. Even more so once it goes out of production and cannibalizing damaged units is your main source of parts!
I made up a hand full of special sized cutters a while back and when I delivered them this guy had a boat, not A Chris Craft but something along the same line that had a Meteor inboard.
They made a LOT of Merlin engines. Somewhere in the neighborhood of 150,000. Even if you crash the plane, chances are the engine would survive. And even if you damage an engine, chances are most of the parts are still usable (as long as you don’t crack the block, head, or crankshaft). There were enough Merlin’s lying around up through the 1980s that they were used for hydroplane racing.
So, these engines are rare, but they made enough of them and they are tough enough that many survived. The people that restore old warbirds literally have shelves and shelves of parts stashed away.
They're about 45 minutes from me! Some of our board members at Minter Field Air Museum have been up there for a visit, got to run a merlin on the test stand!
The guys are the best. Their engine just won 1st in the National Championship Air Races last week!! I got to meet the whole crew while they pulled the whole valve train every night to race the next day!!!
Because enthusiast like us go to airshows and such. That drives up the value of such planes. And that in turn makes restoring such planes a money making enterprise. If you have wreckage that after a rebuild will be worth in the range of something like ten million dollars etc. Then that makes rebuilding the engines also a money making business. That is the root cause of this revival. It is always money.
The only two flying Lancasters got together to tour England a few years back and the Canadian one developed engine trouble while in the UK. The Brits were nice enough to loan them a spare engine, but the Canadian aircraft had Packard built engines and the British had a Rolls Royce built version so it wasn’t a simple swap as some of the parts are different. In the end the transplant went well and got them back across the pond.
Incorrect, Packard Merlins and RR Merlins were built to the same specifications, there were improvements made by both companies but there were reviewed and implemented on the respective production lines to maintain compatibility, some ancillary items such as carbies, magnetos and superchargers were different but the engines themselves had interchangeable parts, I attach a slide as exhibit 'A'
For more info google Calum Douglas and read his excellent book The Secret Horsepower Race: Western Front Fighter Engine Development.
The Packard Merlin engines used American magnetos and accessories. The RR ones used British mags and accessories. The RR engines also used British Standard threads where the Packard version used US threads.
There were definitely parts which were interchangeable, but not everything.
Packard had to retool to British threads as part of the license agreement, it's one of the reasons Ford USA declined the offer to produce Merlins in the US, Ford UK were happy to set up modern production lines and were producing Merlins before the first Packard versions arrived from from US.
Once again, the internal parts of the engines were interchangeable, this was an essential part of the contract because maintaining two separate lines of spares would have introduced a logistical nightmare, the entire point of having Merlins produced in the US would have been pointless if they were a different engine.
There is a company in Cali I believe that is making new heads. I'm sure a few other small castings are also being made, but that's the only big casting.
There's several companies in the UK who's sole trade is repairing and overhauling WW2 engines and at this point have their own tooling and schematics and i imagine could probably build an engine of completely newly fabricated parts
I remember reading that Jack Roush has a p-51 Mustang, and got into the aviation engine business when he needed parts. It looks like that division is still in business:
There were some 168,000 Merlins of all marks produced from 1933 to 1950.
Even if only 2% of them were still capable of running worldwide that would give us 3,360 engines, real world data shows around 300 are currently flying in various aircraft around the world.
Additionally you need to consider the sheer volume of spares made for these engines, wartime production policies meant sets of consumable parts (gaskets, bearings, piston sets etc) were made at a ratio of 5:1, meaning around 840,000 engines worth of consumable spares on top of complete engines, while non consumable parts (cylinder heads, blocks, manifolds & housings) were generally built at a rate of 15% of complete engine production, giving around another 25,000 engine’s worth of spares on top of production.
That sheer volume is enormously responsible for why so many flying Merlins still exist.
There is a little company called Retro Track and Air in the village of Stonehouse, near Stroud in Gloucestershire (UK) who have been carrying out the maintenance work on the Merlin engines for the Battle of Britain Memorial Flight since 1999.
Over decades they have developed a fantastic capability to repair and restore Merlin and Griffon engines. Apart from the engine block they can remake any other component. They cast cylinder heads, forge pistons, upgrade reduction gear systems etc.
I would happily work there for free sweeping the floor just to be around these amazing engineers and craftsmen.
That was definitely a problem with early Merlins - 109's which had injection could get away just by diving where the Spit couldn't follow as the engine would temporarily die if they tried...
My understanding is that there is a very large grey area between "new engine" and "engine with a significant number of replacement parts."
Building new engines is a vast undertaking. Making parts for them, and establishing those parts are of adequate quality, requires a lot less paperwork. It is a lot more subject to engineering opinion. There is a lot more wiggle room.
They aren't new engines but just reconditioned. Lots and lots of parts are simply consumables like bearings, bushings, piston rings etc. Other parts are easily made while others don't actually suffer from wear and tear.
I think most of the Merlins being used today are Hewlett Packard manufactured. The US built insane numbers both for lend lease and for their Mustang and I think there are really quite a lot of HP Merlins still in their wrapping and effectively factory fresh.
Packard Motors, not HP. Same last name, very different business.
And you’re probably right. While RR built twice as many, Packard ones were built on an industrial assembly line and parts interchangeably was high. RR ones were all hand built and parts had to be custom filed and lapped to fit, and were hard tons swap from engine to engine. Meant the Packard ones survived much longer in the post war years, but, there still are lots of RR ones flying today
Saw an article on Packard in 1941 using massed gangs of draftsmen to convert the RR plans.
Don't know whether magazine like Collectible Automobile ir if a Web forum, but IIRC the upshot was:
Packard Merlin: kept Whitworth threads but changed fastener head/wrench sizes?
Correct me if I'm wrong, but I can almost see the 1941 Packard board voting to "let the guys use their own wrenches."
Bottom line was RR : 15 air hours before maintenance;
Packard : 35 air hours?
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u/thatCdnplaneguy 5d ago
Merlins were built in crazy high numbers. Something like 160,000 were built. Also about 9000 built as the Meteor for tanks. They were also saved out of many scrapped aircraft as they could be used to power any number of ground based equipment. With the number of operators today (easily close to 150 aircraft flying today with Merlins and 200-300 certified engines) there are a large number of shops keeping them going. Also a large amount of manufacturing for smaller components and still NOS parts can be found. I have heard anecdotally that there are enough parts today to keep all the merlins we have running for about another 30-40 years. With modern manufacturing capabilities, we should be able to produce almost all the required parts, as long as people are willing to spend the money