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Thread: Merlin engine

  1. #1
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    Default Merlin engine

    Hello again everyone
    Are there any Merlin engine experts on this forum? This time I'm keen to know about Merlin engine serial numbers. I've managed to get hold of 4 engine numbers for Lancaster PB228, is there any way of identifying what spec they are and where they were built (Packard, Crewe or Derby)?
    Port outer: 7873/326707
    Port inner 11204/246200
    Starboard outer: 9802/244798
    Starboard Inner 9501/244497
    Cheers to everyone who answered my last posting.
    Captain_M

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    Don't know if you've tried here:

    http://forum.keypublishing.co.uk/forumdisplay.php?f=4

    Might be worth a go.

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    Captain_M,
    PB228 was nominally a Mk. III so should have had American-built (at Detroit of course!) Packard Merlin 28 or 38 engines (roughly equivalent to RR Merlin 24 and 22 respectively according to "The Merlin in Perspective - The Combat Years" by Alec Harvey-Bailey, published by RR Heritage Trust 1983.) The two numbers you quote for each engine would be the manufacturer's number (presume the shorter one) and the Air Ministry number (the long one, should have an "A" prefix.) RR in the UK had three factories producing Merlins (Derby, Crewe and Glasgow) while the Ford Motor Company also had a line at Manchester (Degenham, where they normally produced cars!) Unfortunately I do not have access to the serial numbers allocated to Merlins of different series, but I imagine that RR must have allocated "blocks" of numbers to the different factories in the UK as all production examples were supposed to be identical, whereas the Packard Merlins had many differences in carburation, propeller reduction drive and supercharger drive as well as cylinder block design and Bendix magnetoes. I have read that there were (a few) individual Lancasters that had a mixture of Packard and RR Merlins fitted on the same airframe. Now I imagine that this would be a highly undesirable practice as a rule (except in an exteme emergency), as the differences between the two engines were numerous and required different procedures for starting and cruising, etc, mostly because the American engine had the Bendix-Stromberg injection carburettor, whereas the RR engines had the older float type.
    Sorry I cannot be more specific on the numbers but hope the above rambling makes the situation a lillte clearer.
    David D

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    I'm sure I read somewhere that the different marques of Merlins built by Packard had a "2" prefix, e.g. R.R. Merlin 66, but Packard Merlin 266.

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    I believe the 2xx series belonged to the 2-stage engines, and were not applied to the single-stage engines fitted to Lancasters.

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    The Merlin 266 was indeed a two-stage engine (fitted mostly to Spitfires such as the Mk. XVI) but the Merlin 225 was equivalent to the single stage (2-speed) Merlin 25 and was fitted in Mosquitos, particularly those built in Canada and Australia. However I am not certain that any two-stage Packard Merlins were fitted to British-built Mosquito variants which would require this configuration (the later PR, NF and B versions). Early Packard Merlins delivered to the RAF had RAF Mark numbers such as 28 and 29, or 68, 78, but some later versions had the "2" prefix, for reasons which to me seem obscure (change of nomenclature policy?) The latter system (addition of a prefix number) is similar in concept to that adopted by the RAF stores system during WW2 when all American equipment (mostly in the form of smaller items rather than complete aircraft) was numbered in the stores system with a "1" prefix added to the Section number to clearly identify the trans-Atlantic origins. For instance British-origin radio and radar equipment had the reference 10, US-origin had reference 110.
    David D

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    Could it be a way of relating similar engines? So the Merlin 225 could be a direct replacement of a Merlin 25? This doesn't, unfortunately, quite work for the Merlin 66 and 266.

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    Graham,
    As you suspect, I think the later RAF designations (with the "2" prefixes, that is 224, 225, 266) for imported Packard Merlins (which were Lend Lease engines, not to be confused with the engines fitted in P-40F/L Kittyhawks or the later Mustangs which were also Packard-powered, although supplied under Lend-Lease) were noted as being roughly equivalent to certain RR engines, but were so different in other ways (notably with respect to accessories) as to be considered different engines entirely for spares back-up purposes, so were normally restricted to British aircraft with different mark numbers (the aircraft that is, with best examples being the Lancaster I/III and Spitfire IX/XVI.) I have checked on Mosquitos, and no British-built examples were fitted (at manufacture) with Packard engines, only the Canadian and Australian built versions. When you read the pilot's notes for the mentioned Lancaster and Spitfire versions (as well as the Mosquitos) you can see why you could not simply swap engines without also incorporating a considerable number of required modifications to suit the different carburation (mixture) and ignition systems, etc.
    David D

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    Default Merlin engines

    Ta guys for your input.
    Cheers
    Captain_m

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