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Semi-OT: Another round of "What's this aircraft part?"

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  • Semi-OT: Another round of "What's this aircraft part?"

    I've got two pairs of these in slightly different material. I hope these photos are enough, because I had a bear of a time getting these up to Photobucket. The ads were so bad it was killing my computer's performance. The assembly shown appears to be some kind of stainless steel. It has a twin, but the other pair appears to be a different (and less pretty, IMHO) material.

    Where the big bolt is installed to close the halves, there are 4 stampings. On one side, the "top" half has "ST.21/" and "/13.145/2". On the other side, the "top" half has "ST.2212" and some kind of logo. For the "bottom", one side also has "ST.21/" and "/13.145/2", but the other side has "ST.2211" and again, the logo.

    With the gap between halves as shown in the second photo, the ID is nice and round and measures 3 5/16" (3.3125)

    On the back side hinge pin (as shown below), and on both clamp halves, there appears to be a tiny stamp that resembles a head-on view of an airplane.

    My guess is (obviously) that this is some kind of clamp, perhaps part of the propeller assembly on some kind of vintage aircraft. (based on the part's coming from the estate of someone interested in tinkering on vintage prop planes) Anyone recognize it or whether it has more than decorative value? Thanks.

    -M








    The curse of having precise measuring tools is being able to actually see how imperfect everything is.

  • #2
    Looks like a clamp that is used for sealing a union for a compressor bleed air tube and/or a turbine air start tube.

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    • #3
      The part number on the actual clamp links up to McDonnell Douglas Helicopter. The material is probably monel. The part numbers on the bolt end are for the bolt and nut. Since it is monel it is for a very high temp application.
      Free software for calculating bolt circles and similar: Click Here

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      • #4
        Originally posted by Evan View Post
        The part number on the actual clamp links up to McDonnell Douglas Helicopter. The material is probably monel. The part numbers on the bolt end are for the bolt and nut. Since it is monel it is for a very high temp application.

        What is it about the part numbers that link to McDonnell Douglas?

        I see the "ST" that Boeing used. That referred to "special tool" so if it was Boeing's it would be a tool instead of a part.

        Oh, on second look I see a triangle outline. Is that McDonnell/D's?

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        • #5
          In case it matters Boeing owns McDD

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          • #6
            I did a somewhat fancy way of Google lookup. Too much work to explain I'm afraid. I could easily spend the rest of my life instructing re computers and I may well end up doing that anyway.

            If it is a tool it wouldn't need the lock pins. (unless it is for flight testing)
            Last edited by Evan; 03-18-2017, 10:00 PM.
            Free software for calculating bolt circles and similar: Click Here

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            • #7
              more clues

              I wasn't expecting McDonnell Douglas helicopter. Maybe some kind of vintage prop/piston aircraft. More clues in the form of logos. The first one is stamped on each of the clamp halves, on the top of the hinge pin, and the side of the large crown bolt. The second is as shown. I think that's "E", "N", and either "M" or "H". I spent a while this morning looking over many, many aircraft related logo images, but never saw anything like these.









              Ring any bells anyone? I'm stumped.
              The curse of having precise measuring tools is being able to actually see how imperfect everything is.

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              • #8
                Could those "logos" be an inspection stamp?

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                • #9
                  Originally posted by Mike Burdick View Post
                  Could those "logos" be an inspection stamp?
                  I assumed that the part was pretty important based on the crown nut and cotter pin arrangement and the close fit. It really does fit together nicely with no play that I can readily detect. Once someone's gone to the trouble of making a precise and close-fitting part such as this, wouldn't an inspection stamp be a bit heavy handed? I don't know much about the world of aviation parts - that's why I ask. Thanks.

                  -M
                  The curse of having precise measuring tools is being able to actually see how imperfect everything is.

                  Comment


                  • #10
                    I don't want to be master of the obvious, but with the propeller logo it could be a clamp for a prop blade grip. You can find various pics online of old variable pitch props with similar looking clamps.

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                    • #11
                      Originally posted by Machine View Post
                      I don't want to be master of the obvious, but with the propeller logo it could be a clamp for a prop blade grip. You can find various pics online of old variable pitch props with similar looking clamps.
                      That's one of the things I imagined it could be. Somewhere around here, I had what I think was a propeller hub, but I couldn't say whether it was for a variable pitch arrangement. And yeah, that would make it an important part, with a few safety features to ensure it stays put once installed.

                      All of these parts came from an estate, like I said. The way I got a lot of this aircraft stuff was from a wake-up call from a friend early one Saturday morning years ago. "Come get this junk now, or it's going to the dump." So I loaded up a bunch of stuff in the trunk and have been figuring it out gradually over the months and years. Thanks.

                      -M
                      The curse of having precise measuring tools is being able to actually see how imperfect everything is.

                      Comment


                      • #12
                        Originally posted by Evan View Post
                        I did a somewhat fancy way of Google lookup. Too much work to explain I'm afraid. I could easily spend the rest of my life instructing re computers and I may well end up doing that anyway.
                        Excellent non-answer
                        If you benefit from the Dunning-Kruger Effect you may not even know it ;-)

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                        • #13
                          I am not positive but in the very long PDF file of MD parts it appears that the part is monel. That doesn't make much sense for propellor parts. Monel is super expensive and is used in turbines or exhaust systems perhaps. I am not sure how to tell if it is monel or not. It is an alloy I have not worked with.
                          Free software for calculating bolt circles and similar: Click Here

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                          • #14
                            Exhaust clamp for flex pipe.

                            JL...............

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