Building the Rolls Royce Merlin engine, doc - Page 2
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  1. #21
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    Quote Originally Posted by LockNut View Post
    It wasn't the government per se that told HF that. It was Bill Knudsen, former head of Ford manufacturing. Read the great book "Freedoms Forge". Most amazing story about the second industrial revolution created by WW2.

    Paul
    Not bad for a bicycle mechanic from Denmark.

  2. #22
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    Nice to hear from you Asquith; I was going to let this thread shrivel on the vine until I saw cyanidekid's sensible post and your erudite replies.

    AC Lovesey was in charge of Merlin development from just before the Battle of Britain to the war's end; in 1945 he described the development process and his paper is the first link in the attached;

    Development of the Rolls Royce Merlin Engine | Aircraft of World War II - WW2Aircraft.net Forums

    The other links will be of interest also.

    A very good article on the Packard Merlin is Packard as an Engine Builder The Packard Merlin (Robert Neal).

    Google finds it but gives a link that's longer than the Book of Jeremiah; if you Google "Packard as an Engine Builder" you will find it.

    Lovesey, in his introduction, mentions the various Merlin plants and, of course, makes no distinction between Merlins from any factory; all met RR's stringent specifications and that was that.

    It's interesting that the development work was done at Derby because " ... the original Derby plant, which was not laid out for mass production, was always the first in the field with the new improvements and these eventually filtered out into the main producing plants after production difficulties had been overcome".

    Neal's paper, drafted as part of his book on Packard aero engines, makes some interesting comments about the preparations for building Merlins; the engine had 144 different threads/sizes and none was native to the US.

    Improved supercharging was the key to performance improvements, although the mechanical engineers had to work hard to provide mechanical reliability and the carburettor folk had to find ways of providing huge amounts of air & fuel to the engine..

    The air war was fought at different levels at many stages during the conflict, and there is no "one-size-fits-all" for supercharging at low, medium and high altitudes

    Stanley Hooker was the genius who evolved various superchargers (eg. the two-stage design); as the title of his book indicates, he was not an engineer but a mathematician who studied gas flows.

    The mechanical engineers produced the two-speed supercharger drive, a fine device if not quite as sophisticated as the variable-speed drive used on the DB60x engines.

    It's remarkable that, according to Hooker, RR did not have a dynamometer for high-powered engine development; hp, torque etc were all calculated and only later tests confirmed that those figures were dead-accurate.

    There is a good article from Flight magazine, December 17th, 1942, entitled Rolls-Royce Merlin "Sixty-One"; I have a pdf so it should be found by searching.

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  4. #23
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    Plannerpower,

    Thanks for the links. Only when I got near the end of “Packard as an Aero Engine Builder” did I realise that I’d read it some time ago, when I was seeking information on Continental’s production of Merlin engines.

    The author perpetuates the idea that 'The British did not specify tolerances and fits' !

    I’m intrigued to know how R-R could have managed to use 140 different screw threads, with just four different systems – BSW, BSF, BSP, BA, each of which was associated with only a limited number of standard sizes. So how……

    As for dynamometers, R-R had them aplenty, for development and for production testing. I think Stanley Hooker was referring to R-R not having climate controlled engine testing facilities, such as were installed at Wright Field.

    Curious about testing regimes in an earlier era, I went to the excellent RRHT book Eagle – Henry Royce’s first aero engine by Derek S Taulbut. There's a 1915 photo of a R-R Eagle on the test bed. It has not one but two dynamometers, one at each end. One's a Heenan & Froude water brake, while the other is a Royce dynamo. Presumably the dynamo was to put a lesser load on the end of the crankshaft that drove the auxiliaries?

  5. #24
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    There are certainly some interesting statements in that paper.

    It may be that the good round gross of sizes included those "modified" by RR and/of different lengths; in any case, it's possible to understand the problems for Packard of these threads for which even basic taps & dies couldn't be bought in the US, never mind geometric die head chasers or even, perhaps, collapsible taps.

    Packard's no doubt exceptional toolroom would have made these but they required accurate drawings.

    All this took time and research.

    I interpreted the "no tolerances" remark as saying that RR did not provide any fitting tolerances so the Packard folk had to work them out; it's inconceivable that RR had no such essential information.

    Re dynamometers; I don't have Hooker's book and memory is dangerous but I feel that I've seen this statement either there or elsewhere.

    This fascinating period video;

    YouTube

    certainly shows Merlins on dynos.

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    Interesting thread and very informative - I have to read some of the references.

    Rather than worry about who built it and how, it struck me how little difference it would make to the aircrew. I've been cleaning up my office the past few days and filed away a copy of and uncle's retirement biography that told of his 30 year USAF career. He was one of 7 brothers - my mother being the only girl - 5 of whom served in WW2 and beyond. He was a P47/P51 driver with 101 combat missions from England. Twice he sustained damage from ground fire and had to 'leave the aircraft'. Had to dig it back out and reread it.

    First time he knew his radio was out and got separated from the rest of his flight - summer of 44 - but did not realize he was losing coolant. Had escorted bombers and then strafing railroad yards in support of the 3d Army. Of more concern was the 3 by 3 1/2 foot hole in the right wing and the fuel coming out. He climbed above the overcast and the engine overheated, catching fire - by this point he was over the Channel. Figuring the whole thing was going to go up he bailed out. By blind luck the lookout on a Brit minesweeper saw him drift out of the clouds behind the ship. They turned around and picked him up - he always said faster than if he had called air-sea rescue. That same day his oldest brother got a pass and came to the field to see him - and was told he was MIA. So they gave him a bunk and he was feeling pretty down - but about 10 that evening the younger brother showed up and they had a good reunion.

    On his 101st mission he was again the victim of ground fire - on 21 March 1945. Again he bailed out, but on the wrong side of the Rhine as he had a total failure of the aircraft - they were working over a field used by the Luftwaffe jets. This time he ended up in Stalag Luft 1 until the Soviet Army overran it on 1 May.

    Like many, this engine and the aircraft it was part of kept him alive. He spent 22 months, coming to England as a 1LT and ended up a LTC commanding the squadron. I don't think he really cared about the specs on it - even if he was an Ohio State engineer!

    Dale

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    To continue the theme of the human side of the engine...
    About 20 years ago I had a project at the RR plant in Bristol England were many of the Merlins were built. RR had decided the building would eventually be abandoned long before which made it an accidental museum.
    The lack of investment and updates left it much as it was during the war. (it was subsequently torn down)
    The machine I was installing happened to be going into the "runoff shed" where every Merlin was started for the first time. Some of the camouflage paint was still clinging to the exterior walls, but most impressive was the cafeteria. During the Battle of Britain the workers had painted an amateurish mural of the air battle on the ceiling of the room, complete with arching contrails. I can only imagine the emotional connection they had with the scene, knowing that the pilot's lives literally hung on the engines they were building.

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