Sperry Ball Turret for Avro Lancaster?

Discussion in 'Aviation' started by lordish, May 21, 2010.

  1. lordish

    lordish New Member

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    Does anyone know if AVROs ever did any testing of adding an American Sperry Ball type ventral turret to the Lancaster? Eventually a Martin mid upper turret was adopted.

    Considering that the periscopic ventral turret was a failure the manned Sperry turret would seem to be an obvious choice. It certainly would have been a surprise to your jaded German Ju88G6 pilot.

    lordish
     
  2. Airframes

    Airframes Benevolens Magister

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    Don't know of any testing, or even a consideration. I would have thought the structural requirements, plus the weight, would have been a major issue, and that's before the extra crew member, and ammunition, not to mention logistics (at that point in the war. The Martin turret arrived late in the proceedings).
     
  3. timshatz

    timshatz Active Member

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    Didn't the Halifax in some Groups have belly guns?
     
  4. tomo pauk

    tomo pauk Creator of Interesting Threads

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    #4 tomo pauk, May 21, 2010
    Last edited: May 21, 2010
    Perhaps deletion of dorsal turret installation of a ventral one might've been good thing, to defeat Schraege Musik without drag weight penalty? Pure hindsight here - RAF learned about the threat a year or two after Luftwaffe put it (S. musik) to a good use...
     
  5. lordish

    lordish New Member

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    I don't think weight overall would be a problem. After all the Lanc could carry Grand Slam. By looking at the pictures (I'm an aircraft mechanic) I'd think the big problem would be either center of gravity or where to put the main attachment for the shaft the bottom of which the turret rested. In any event it would have to have been the retractable version of the turret because if it were in firing position, I'm pretty sure the tail wheel wouldn't have touched the ground.

    Let me check around on the history of the turret itself.
     
  6. kration

    kration Member

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    #6 kration, May 21, 2010
    Last edited: May 21, 2010
    EDIT 2: - just reread the first post and it does refer to the periscope turrets! But, thought I'd leave my post here as it raises a couple of points.


    I'm not sure about the Halifax, but the initial versions of the Short Stirling had a ventral turret which I think was remotely controlled? (and apparently the Wellington too! - see below). I've always been puzzled as to why they were removed as the lack of belly cover was an obvious weakness in defensive fire. They were replaced by guns in side windows, but I'm not sure how effective they would have been!

    EDIT: I'd be interested see a close-up pic or diagram which showed the FB25 turret - my cursory internet search couldn't find anything.

    This quote below explains it pretty well:

    "The Stirling Mk I Series I carried three Frazer Nash gun turrets – the two gun FN5A in the nose, the four gun FN4A turret at the rear and a two gun retractable FB25A ventral turret underneath the aircraft, each using the standard .0303in machine gun. The ventral turret was not a success. It had a tendency to lower itself when the aircraft taxied, suffered from poor visibility, and slowed the aircraft by around 10 mph (the same problems had caused the removal of a similar turret from the early Wellington bombers)...

    Mk I Series II

    The main change made for the Series II Stirling was the removal of the FN25A ventral turret. Provision was instead made to carry two .303in Browning machine guns in side windows in the fuselage (just as in the Wellington). The FN4A turret at the rear was also replaced by the superior FN20A, also with four .303in machine guns."

    Taken from:
    Short Stirling Variants
     
  7. Glider

    Glider Well-Known Member

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    I am pretty sure that some Halifax BIII bombers in BC had a ventral 0.50 but it wasn't a turret also the H2S radar couldn't be carried as well as the gun.
     
  8. Airframes

    Airframes Benevolens Magister

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    There would probably have been clearance for a Sperry ball turret on the Lanc. But when I mentioned the weight, this was not directly related to the extra weight to be carried, but the weight of the structure of the turret, the gimbal, suspension yoke, seating and mount, plus the ammo. The structural modifications required would, I believe, have been rather major.
    Also, the ventral FN turret had been fitted to early Mk1 Lancs, and was neither successful, advantageous, or liked by the crews. Visibility was next to nil, and with slow traverse, this negated the whole point of the turrets' existance, and they were removed, and deleted from production lines.
     
  9. Waynos

    Waynos Active Member

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    One of the Dambuster's Lancasters had a lashed up ventral machine gun position. There was a documentary on TV recently where the wreck was excavated and was identified positively because they found this gun mount. It seems it was unique.
     
  10. Snautzer01

    Snautzer01 Well-Known Member

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    no need for Sperry
     

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  11. T Bolt

    T Bolt Well-Known Member

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    That turret was used on some of the early B-24D’s. My father used them in training at said they pretty muck su*ked. He said you would get vertigo looking through the periscope and loose all track of where you were looking, not to mention losing your breakfast!
     
  12. Snautzer01

    Snautzer01 Well-Known Member

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    see here

     

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  13. Milosh

    Milosh Well-Known Member

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  14. lordish

    lordish New Member

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    I'm beginning to think that the Lancaster ventral turret problem had fallen victim to a syndrome known in bureaucratise as N.I.H.---Not Invented Here. Years were wasted developing turrets and other systems. However, the RAF had available literally thousands of Sperry ball turrets, and by the beginning of 1944 there was available a successful and completely remotely operated aircraft defense system developed by General Electric for the Boeing B-29. I don't get it. The RAF used American manufactured AI radars, why couldn't they use the turrets which would have saved thousands of Bomber Command lives?

    Ironically, in Bomber Boys, a wonderful BBC documentary about the Lancaster and Bomber Command, Ewan MacGregor read "The Death of the Ball Turret Gunner."

    Lordish
     
  15. tyrodtom

    tyrodtom Well-Known Member

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    I think one of the reasons they removed lower turrets was because a fighter approaching from below is going to be invisible with a blacked out Europe below them.
    Unless there's a moon out, or a lot of background lights from towns and cities, below is nothing but black.
     
  16. Glider

    Glider Well-Known Member

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    The RAF 100 Group had a small no of B17s which were used at night. These were of course equipped with the Sperry ball gun but they were removed after a few months of service as they were impractical at night. However I don't actually know what they meant by impractical. It wasn't beacuse of any weight problems that I do know.
     
  17. tyrodtom

    tyrodtom Well-Known Member

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    I think that was just another way of saying the gunner would have very little chance of seeing a fighter approaching from below at night, until it opened fire.
     
  18. nuuumannn

    nuuumannn Well-Known Member

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    Defiant night fighters used the same tactic in late 1940 - early 1941 before the Luftwaffe nightfighters adopted fixed guns, by rotating the turret forward and aiming the guns up into the belly of the enemy bomber.

    There was certainly space in the Lanc fuselage aft of the bomb bay to put a Sperry turret, but the mid upper turret would have to be removed, there wasn't enough space for both. No doubt there would have to be local structural strengthening to hold the thing in place.

    The Martin turret was only fitted to Canadian built Lancasters.
     
  19. fastmongrel

    fastmongrel Well-Known Member

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    Maybe to fit H2s or other electronic equipment.
     
  20. Airframes

    Airframes Benevolens Magister

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    Yep, the space was used to mount 'Jostle' ECM equipment, or as it was known then, RCM equipment.
     
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