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Thread: 5D/657 bomb release T handle

  1. #1
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    5D/657 bomb release T handle

    Hi all

    wonder if anyone with access to Lancaster or Halifax publications can help us. The last item to add to our Stirling main instrument panel is the bomb release tee handle 5D/657; this seems to have been a common installation across the heavy bombers but info on the Stirling installation is pretty scant.

    We assume that the details are pretty similar for the 2 other aircraft types so if anyone has a scan from the Vol 3 and/or schematic from the Vol 1 it would be very much appreciated. We have the handle itself but that is all so an indication of the other components would be a help.

    for info the tee handle for the Lanc is in the top RH side of the panel in the following link

    http://www.lancaster-archive.com/cockpit.jpg

    TIA

    John

  2. #2
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    Hi John

    What is it that you are after exactly? You say that you have the handle, do you mean just the handle or the whole assembly, that is whatever it is that the handle pulls on - contacts - cable, etc.

    If the handle is on a schematic - it should be on the Stirlings (wiring?) schematic too.

    I don't think I can actually help but I'm just inerested to know what you are looking for.


    Cheers
    James

  3. #3
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    Hi James

    As far as we can ascertain, the handle fits into a conduit which pulls on a Bowden cable which feeds into a splitter operating a further 2 Bowden cables which operate the two 16 pole bomb selector switch panels at the bomb aimers station. What we're after really is details of the conduit and mounting on the dashboard that the handle fits into as it's not too apparent how this actually pulls the cable. A parts call out and any associated Vol 3 type diagrams would aid us greatly in our understanding of the system. Of course if anyone has any of the required parts that would be even better

    cheers

    John

  4. #4
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    Cheers John

    I've never looked too deeply into that part of the Stirling system but it always seemed to me that that control had to be a bowden cable type arrangement.

    Interestingly, there are dashboard panel pics of the Stirling that have two of these 'toggles' so I'm guessing that that system had a Bowden cable per bomb selector.


    James

  5. #5
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    Hi James

    we looked at that photo yesterday and we think it's either the prototype or a very early Mk I. A further photo of the stbd side of the bomb aimers station shows the splitter box with the 2 Bowdens coming from it

    John

  6. #6
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    Hi John
    I have the whole assembly. Send me an email with your exact questions and I can take measurements / photos.
    Cheers Paul
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  7. #7
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    I would also be very interested to see the photos! Could they could be posted on here, please?
    One of my intended projects is to build a working Lancaster Bomb-Aimer's Panel, and although I won't be building the Pilot's panel, it would be nice to try to replicate the jettison handle.
    Many thanks,
    Andy

  8. #8
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    So now that the operation of the funny toggles has been explained - it opens up the next question as to why the bomb jettison has to be mechanically connected to the Bomb Selector but the 'Containers' jettison can be an electrical switch on the dashboard (Stirling at least)?

    Next question being why must the containers be released first?

    Cheers
    James

  9. #9
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    James, the Lancaster is the same. It doesn't help with the Containers question, but I can see the logic of the mechanical Jettison Handle. To jettison all bombs requires an electrical circuit to each bomb station to be closed. Each circuit is independant, so this requires a Jettison switch with as many poles as there are bomb-stations, this being provided by the Jettison Bars. The easiest way to provide a Jettison function to the pilot as well as the Bomb-aimer is with the mechanical link, much simpler than trying to do it electrically.
    Andy

  10. #10
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    Hi John and Andy

    Well the whole thing is rather uninteresting. I have added some photos of it from the front and rear (hard to get a good photo though sorry) as well as where the cable joins the bomb selector. As to details of the conduit, on mine at least it is just a 1/4 inch diameter flexible metal tube with a black coating over it - just like what you'd find on the brakes to a bicycle. And how does the handle pull the cable, the handle has a 4 sided 'rod' at the back and the cable is fixed directly to this.

    Apparently this was installed in 2 ways, either flush with the instrument panel or on a 45 degree angle towards the pilot. My one is on the angle and has spacers to allow this to mount properly.

    As to dimensions, the attachment at the front is a 1 inch square and 1/32 inch in thickness, it has a round bit protruding which is 1/2 inch in diameter and 1/4 inch tall with the square hole in the middle. It is mounted with 4 bolts and the spacing of these is 3/4 inch center to center. There is a threaded tube on the rear which is about 2 inches long and 3/8 inch in diam, the thread has a 'nut' on it, don't know the technical term but it is actually round with slots in the top side and would need a special tool to tighten. There are 2 'clamps' that hold the cable to the tube.

    I hope this helps in some way.
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  11. #11
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    After looking at it a bit more it appears the tube part started off as all being 1/2 inch and then had the thread cut in part of it. The tube is then passed through the plate from the front and held in place by the 'nut'. Should be easy to make one.
    Regards Paul
    Last edited by ozjag; 13th March 2018 at 10:45. Reason: typo

  12. #12
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    Paul, many thanks!
    Andy

  13. #13
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    Hi Paul et al

    many thanks for the replies. Paul, totally forgot that you have a panel and the info you've given us is invaluable. Can I ask how exactly is the Bowden cable attached to the square section rod at the back of the handle. ours has a slight groove in it but no real indication of how the cable is actually fixed to it.

    cheers all

    John

  14. #14
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    It looks like the cable is brazed into the groove. Also above where I said there were 2 clamps that hold the cable to the tube, it is actually one piece on the bottom and 2 pieces on top so that they are held together.
    Paul

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  15. #15
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    That's awesome Paul, thanks for that

    How's that Jag coming along?

    John

  16. #16
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    Hi John,

    no problems, I am just happy that I can assist from such a long way away, 'one day' I will definitely come over for a look around. Just email me with any other specific questions about the bomb jettison.

    As to the Jag, progress has slowed down considerably, all of the easy stuff has been done and all of the common parts sourced. I'm now into the difficult and unobtainium reign so things don't happen quickly.

    Cheers Paul
    Facebook: Aussie Cockpits

  17. #17
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