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SE 5A propeller Diameter 2520?

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  • SE 5A propeller Diameter 2520?

    Hello,
    This is my first posting and would be very grateful if someone could confirm/identify a prop that has been cut in half through the boss. The only markings remaining are:

    HISPANO
    SUISA
    SE 5A
    D 2520
    P 2850

    These are stamped across the width on each side of the boss.
    I believe the usual markings on this prop ( it looks like an AB8080?) give diameter as D 2514. Were the standard markings changed at some point, maybe post WW1, or could it have been a special order?

    Many thanks
    Regards
    Roger

  • #2
    Stamping on both sides is a little unusual, and if it was cut in half why would it still contain identical complete stampings? I wonder if it was stamped by someone other than the manufacturer.
    Dave

    Comment


    • #3
      Hi
      If a propellor has 3/4 stamped after Hispano-Suiza what does this mean?
      I am wondering why the N numbers always seem to be different. In my case N342.
      Regards, Tim

      Comment


      • #4
        Roger,

        Could you post a photo which shows where the data is stamped, and also the style of the stamping?

        Makers were allowed some discretion in prop diameters to allow for manufacturing constraints. Without looking it up, I think it was 10mm. I have seen 2515 on an AB8080 prop. And there are many examples of diameters of all sorts of props varying by a few mm. It would seem that many manufacturers stamped the actual dimensions on the prop rather than the theoretical dimension.

        Tim,

        The ratio Ā¾ indicates reduction gearing so that an engine speed of 2000rpm gave a prop speed of 1500rpm.

        From Septmber 1917 all props were given a code number for central accounting. At the same time props came to be ordered in batches of 100, which were identified by the letter G; hence G277 for example. The letter N indicates the number of the prop within that sequence; hence G277 N85. These numbers can date a prop roughly. After 1925 perhaps, some batches were for more than 100 where the N number could have three digits.

        Both of you

        Please tell me any G and N numbers on your prop and also any AID numbers. This will help me construct my database, which I have been doing for fifteen years, having failed to find any at the National Record Office at Kew etc.

        With kind regards,

        Bob
        Bob Gardner
        Author; WW1 British Propellers, WWI German Propellers
        http://www.aeroclocks.com

        Comment


        • #5
          Thank you Bob for the reply. I'll check and reply on the information request.
          One thought; the 1920s were not a time of burgeoning growth in the UK aero industry, so why would propellors suddenly start to be produced in multiples of 100, given that during WWI when aircraft production was vast, the production runs were limited to 100? Regards, Tim

          Comment


          • #6
            Hi Tim,

            The story of prop making in WW1 is that from 1912 to early 1917 many aircraft companies bought direct from a prop making company. The Government also bought via contract, some of which were open ended.

            By 1917, the situation was chaotic, not only in supply, but in tracing the source of props found to be defective, and in the typical manner of soldiers and sailors many pilots thought that a prop from one company was better than one from another; one was stronger, this one gave a higher rate of climb; that prop gave you a higher ceiling.

            It was decided to form a single air arm by merging the RFC and the RNAS and to buy props centrally via the newly formed Ministry of Munitions. The Air Board was established in September 1917 to bring this plan to fruition and decided to do comparative tests on props using the same airframe. The best all round prop was chosen to be the Standard Prop for that aircraft. Sometimes there were two or three different props found to be good enough to be a Standard Prop. Why props were bought in lots of 100, I don't know. It was probably a number plucked from the air. Contracts for props was often for multiples of 100; Four hundred from Sopwith for example. Sometimes a contract for 100 props included two or three different designs of prop.

            At the end of the war, the British aviation industry was treated drastically and cruelly by its political masters. Umpteen contracts were terminated at very short notice, which bankrupted the majority of aviation firms and threw workers penniless on to the streets to join soldiers and sailors recently de-mobbed and also without work. A handful of prop makers survived until 1922, by when only one existed as a prop maker in its own right (The Airscrew company of Great Britain, neƩ The Lang Propeller Company). Prop shops survived in some aircraft manufacturing companies such as Bristol, Gloucester, and Handley Page. So a possible reason for N numbers of three digits, indicating more than 100 props in a batch might well be that there was only one prop maker left apart from in-house shops in aircraft companies. But, as I mentioned above, four hundred props were often made during the war in one contract for four batches. Why this wasn't done after the war I don't know. Perhaps at the slow rate of peacetime procurement it wasn't necessary.

            With kind regards,

            Bob
            Bob Gardner
            Author; WW1 British Propellers, WWI German Propellers
            http://www.aeroclocks.com

            Comment


            • #7
              Bob,
              Thankyou for replying and most interesting notes to Tim's question..
              Sadly there are no other visible marks on the prop as the boss has been 'slimmed down' at some point possibly to clean up the faces for display. The wood does appear to still show the 'bruising' of two square marks/stamps but no numbers are now visible.
              Any canvas covering has long since been removed and the wood polished.
              There are 5 rows of dowls (5mm?) at 8 inch spacing ( 2,4,3,3,2) passing through the laminations starting 1.5 inches from the tip.
              Are these simply to peg the laminations together or were they used for attaching the canvas?
              Could this prop possibly be a 'reject','test piece' or simply redundant store cleaned up for display in an Officers Mess or something similar?
              I havent the means of posting pictures at present but will as soon as I have access to a camera.
              Many thanks
              Kind regards,
              Roger

              Comment


              • #8
                Hi Roger,

                All your suggestions are possible and it is not at all uncommon. It's why the central tenet of this forum is; Don't restore your prop!

                The pegs date it to before mid 1917. The dowels were to prevent creep I assume, either whilst glueing or during manufacture. I've never heard of a prop delaminating in service and most are still sound nearly a century later.

                The laminations overlap so one dowel might pass through two or three laminations. The practice fell into disuse in 1917. No other of the WWI warring nations did such a thing; so these days even a small bit of a prop with a dowel allows me to say British before 1918, until of course I discover something entirely different; such is the lot of a researcher!

                With kind regards,

                Bob
                Bob Gardner
                Author; WW1 British Propellers, WWI German Propellers
                http://www.aeroclocks.com

                Comment


                • #9
                  Hello Bob
                  Sorry for the delay in replying; I was actually waiting for an online auction to end.
                  I now have the item, a half propellor made into a umbrella/stick stand.As I said the N
                  number is 342. It has AID 088 stamped on its own on one side, and on the other a block of 4 AID nos, 408,088,003 and 063. There is an arrowhead with a capital A above it.
                  Because of the gearing I'm assuming it is an SE5a. Only part of the other stamping
                  remains due to the boss being in half.
                  I have another propellor (In my possesion since 1970) for a Sopwith Dolphin. On one side
                  it has AID 840 (indistinct) with an S on each side. The front of the hub has T. Watkins 9626 and a heiroglyph like a signature. On the other side is N55 and G588. The block of four AID marks only one is decipherable, AID 509. I have photos but they didn't come out too well. The blades are green fabric covered and its never been restored.
                  Regards Tim

                  Comment

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