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Flying Scotsman

Discuție în 'Steam Traction' creată de 73129, 24 Aug 2010.

  1. W.Williams

    W.Williams Well-Known Member

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    No way is that serious??
    Cant be...
    Don't hahaha
    Yeah, exactly.

    Sit doon twr12. You have been roasted to within 1thou of your life.

    She sounds bloody fantastic. Chrisp, on time and all beats are metronomic. There are a couple wee wisps from the front end, but given the work carried out so far, its hardly beyond the abilities of Riley and co to see to that. Furthermore she sounds like she is well within her abilities and looks to be walking it. Truly a spectacle to behold.

    EDIT. twr12, just so as we are clear and you don't see me as some arrogant egotistical engineer. The reason the beats are offset is due the placement of the pistons in relation to each other which is of course a function of the relative crank positions. We would need vastly differing pipe lengths to produce the beat patterns SNG set up. Given the compact design of the steam chest/front end, pipe lengths are not the predominant driver of the beat. Gas/steam moves at an incredible pace through the pipework/chambers in these machines, and 3-5 ft will make little difference in comparison to crank position.
     
    Last edited: 6 Feb 2016
    S.A.C. Martin și LMS2968 apreciază asta.
  2. oddsocks

    oddsocks Well-Known Member

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  3. sweetktg

    sweetktg Member

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  4. Fred Kerr

    Fred Kerr Resident of Nat Pres Friend

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  5. Steve

    Steve Resident of Nat Pres Friend

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    No, it doesn't, but I'd humbly suggest that the difference is not significant enough to be detectable by the human ear. Angularity effects would probably be more noticeable and I doubt these are, in reality. The conjugated valve gear will probably provide the biggest variation.
     
    std tank, Sheff și LMS2968 apreciază asta.
  6. 242A1

    242A1 Well-Known Member

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    No. But since exhaust tracts are known to have an influence it would be quite wrong to pretend that they don't. The exhaust beats on the engine do not sound equal but it appears to be performing very well. Perhaps some testing and measurement could be carried out one day in order to know with some certainty what is happening.
     
  7. MellishR

    MellishR Resident of Nat Pres Friend

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    There are two possible irregularities in the exhaust sounds from any steam locomotive; unequal time intervals between beats and unequal loudness. As far as I can recall I've only ever heard perfectly equal loudness from one loco, such that I didn't realise that it had three cylinders until I got home and watched my video – and that was a German one. Every British loco that I've heard has had one or two beats at least slightly louder than the others – enough that one can count the revolutions of the driving wheels without seeing them, though sometimes not easily.

    On the recent videos FS sounds more even than most.

    Audibly irregular timing is rarer, generally combined with major difference in loudness and indicating that the valve settings are seriously out.
     
  8. Big Al

    Big Al Nat Pres stalwart Staff Member Moderator

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    Even exhaust beats (even when you can get it) do not necessarily mean that the loco is set up for optimum performance. That's my take from the comments of people who actually know about valve timing. I'd be inclined to go quiet on this and assume that the Riley team have done the job properly before you get people who did the work coming on here and shouting. :)
     
  9. S.A.C. Martin

    S.A.C. Martin Part of the furniture

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    The Gresley knock is mechanical though due to the conjugated valve gear (as far as I am aware?) - I say this based from videos and recordings of Gresley locos I've heard together with the times I've seen and heard the remaining 3 cylinder Gresley locomotives running. The knock is distinctive and to me is extremely distinctive. It has nothing to do with the beat of the exhaust. That's why, when I said there didn't seem to be anything close to a "knock" earlier, I was referring specifically to the valve gear of the locomotive in question. It sounds to me like Ian Riley's team have it running better than it did in LNER days quite frankly.

    When you consider it took Cook to come to the LNER and change the way locomotive frames and valve gear were set up in overhauls, you wonder why the staff in charge of maintenance and overhauls put up with the ample Gresley tolerances for so long.

    Thompson tried to fix this through changing the number of cylinders being used (succeeding to varying degrees), Peppercorn introduced two further Pacific classes and a variation on Thompson's prototype K1 so there wasn't time to ascertain if he had any affect on maintenance and overhauls, and it was only with Cook, reportedly, that the Gresley knock was all but eliminated from the 3 cylinder set ups.

    It is telling that Peter Townend and a number of other ex-LNER men speak so favourably of Cook's time on the Eastern region. One suspects that Gresley, Thompson and Peppercorn all failed to some extent to eliminate those sort of problems - their attentions were elsewhere.
     
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  10. mrKnowwun

    mrKnowwun Part of the furniture

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  11. JJG Koopmans

    JJG Koopmans Member

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    Lets throw in some numbers, it appears that the middle cylinder is some 7 degree inclined, that would make a 3.5 degree difference minus and plus to the outside cylinders a mere 1% of the total 360 degree revolution. At 5 revs/sec and 6 exhaust beats the different frequency cannot be noticed. As mentioned earlier there can be a difference in loudness of certain exhaust beats. Wear and tear take their toll of the classical bearings in the Gresley gear resulting in an unwanted but different cut-off of the middle cylinder. Cook's maintenance took care of that and the present possibilities of measurements and maintenance will certainly have eliminated any difference in a locomotive just out of restoration.
    Kind regards
    Jos Koopmans
     
  12. 46223

    46223 Resident of Nat Pres Friend

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    That voice of authority hit home, they soon shuffled back! I wonder who it was?:rolleyes:
     
  13. Lplus

    Lplus Well-Known Member

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    The crank positions are offset to take into account the 1 in 8 inclination of the centre cylinder. Interestingly the outer cylinders are also inclined slightly. the upshot is that the centre crank is not 120 degrees from the outer cranks. I believe the offset is 7 degrees (113 and 127 degrees). With perfect set up, and no play in the gear (yes Mr Martin, we've been there) the beats should be completely even. Obviously there is a tiny bit of play, and even a touch of whip, so it's possible to set the gear up to be correct at a certain speed but slightly out at other speeds ( it's even possible to change the centre valve movement by changing the dimensions of the levers - but that's another story....). The fact the loco sounds so even at different speeds is a tribute to the precision of the assembly and the accuracy of the shimming up by Mr Riley and team.

    edit - Mr Koopmans has added something whilst I was writing. I don't think I need to change mine...

    another edit - 1 in 8 is 7.125 degrees.
     
  14. Steve Sienkiewicz

    Steve Sienkiewicz Member

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    Not sure if this has already been picked up elsewhere, but I've just noticed there is Carnforth-York NRM 60mph move activated on RTT for this evening. 5Z89.
     
  15. andalfi1

    andalfi1 Well-Known Member

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    Serious question Steve, I hope I won't be pilloried for ? Please can you explain the variation in exhaust note on both sizes of Spam Can, as in 2 deep beats 1 light beat ?
    Andy
     
  16. 981smithy

    981smithy Member

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    Sounding well at Shap Wells 6/2/16



    Thanks....
     
    S.A.C. Martin, Kinghambranch, Dan Hill și alți 7 apreciază asta.
  17. andalfi1

    andalfi1 Well-Known Member

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    Omg ! Looks like she could give one of my beloved Scots a run for her money !!! :eek:
     
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  18. W.Williams

    W.Williams Well-Known Member

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    She is so on point! Just wow!


    Thanks to Mr Koomans and LPlus for further insight.
     
  19. keith6233

    keith6233 Member

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    Sounds odd here.

     
  20. andalfi1

    andalfi1 Well-Known Member

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    Deleted
     
    Last edited: 6 Feb 2016

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