# Sperry Ball Turret for Avro Lancaster?



## lordish (May 21, 2010)

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


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## Airframes (May 21, 2010)

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).


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## timshatz (May 21, 2010)

Didn't the Halifax in some Groups have belly guns?


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## tomo pauk (May 21, 2010)

Airframes said:


> 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).



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...


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## lordish (May 21, 2010)

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.


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## kration (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.




timshatz said:


> Didn't the Halifax in some Groups have belly guns?



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


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## Glider (May 22, 2010)

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.


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## Airframes (May 22, 2010)

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.


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## Waynos (May 24, 2010)

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.


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## Snautzer01 (May 25, 2010)

no need for Sperry


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## T Bolt (May 25, 2010)

Snautzer01 said:


> no need for Sperry



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!


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## Snautzer01 (May 25, 2010)

see here



kration said:


> ED
> 
> 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.


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## Milosh (May 28, 2010)

Axis History Forum • View topic - Wartime British Remotely Controlled Guns and Turrets

remote controlled 20mm upper and lower turrets


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## lordish (Jan 29, 2013)

Milosh said:


> Axis History Forum • View topic - Wartime British Remotely Controlled Guns and Turrets
> 
> remote controlled 20mm upper and lower turrets



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


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## tyrodtom (Jan 29, 2013)

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.


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## Glider (Jan 30, 2013)

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.


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## tyrodtom (Jan 30, 2013)

Glider said:


> 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.


 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.


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## nuuumannn (Jan 30, 2013)

> RAF learned about the threat a year or two after Luftwaffe put it (S. musik) to a good use...



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.


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## fastmongrel (Jan 31, 2013)

Glider said:


> 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.



Maybe to fit H2s or other electronic equipment.


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## Airframes (Jan 31, 2013)

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


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## Glider (Jan 31, 2013)

No I don't think it was. There was no mention of additional electrical kit being installed just that it was impractical.


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## Airframes (Jan 31, 2013)

You're quite right, I've just checked my copy of 'The Aircraft of 100 Group', by Martin Streetley, my original comment being 'off the top of my head'.
The 'Jostle' transmitter, a very large cylindrical unit, was mounted in the bomb bay of the B-17s so fitted. 
Tests carried out in June 1944, showed that the ball turret installation '_was of little value in night combat_' and, when the aircraft reached the operational units, having passed through Scottish Aviation at Prestwick, where modifications and RCM equipment fit were carried out, the ball turrets were removed. 
On the 'G' variant, 85 of which were supplied to the RAF, the turret well was plated over.
Depending on the internal RCM equipment fit of the 100 Group aircraft, the area was used to mount other equipment as required.
It was the B-24s used by 100 Group which had the 'Jostle' transmitter in the ball turret position, with the aperture blanked off.


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## Completeaerogeek (Sep 13, 2016)

lordish said:


> 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


Yes early Lancasters had a ventral turret with a periscope sighting system but it was difficult to use and with no significant night fighter threat early on, it was dispensed with. Unfortunately with the appearance in 1943 of German aircraft fitted with Schrage Musik upward firing cannons, the lack of ventral armament was something that was regretted once the RAF figured out how they were losing so many aircraft but by then the H2S cupola was being fitted and there was nowhere to fit a ventral turret.


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## Capt. Vick (Sep 14, 2016)

Waynos said:


> 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.



I guess it didn't help them...


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## wuzak (Sep 14, 2016)

Capt. Vick said:


> I guess it didn't help them...



Not much use at low level either.


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## yulzari (Sep 17, 2016)

RAF issues with the Sperry ball turret included internal reflections hampering night vision, gunner battle degradation at -40 degrees in a very cramped position, generally poor night vision generally and the provision of enough electrical power. 

Combined with these was the sheer weight of the whole package and the extra framing to take the point load where the turret hung with the additional lateral and vertical loads of it in battle manoeuvres. It was not a field modification but a major production line alteration.

A cultural difference was that the USAAF measured in missions. Bomber Command in tons carried. Using a Sperry ball turret meant the loss of some bomb load or restriction of range. This needed to be made up by additional sorties so the losses saved by such a turret might well be balanced by the losses incurred amongst the extra flights. In the long term a remote set of upper and lower turrets were in development.

There was also the resultant loss of H2S radar which fitted in the same hole. It was a bomb multiplier by allowing more accurate bombing so it's loss again meant more bombs would have to be carried to Germany for the same effect, by additional aircraft which would be themselves subject to losses. 

I think that this turret was the right answer to the US needs but the wrong one for Bomber Command. WW2 bomber aircrew I have spoken with commonly felt that gunners were principally there to observe and give warning to the extent that a few had strict instructions not to fire as it might give the location away (in one case' unless he is close enough to throw the ..*! guns at him'. They generally felt that a swift tight corkscrew would be more likely to save the crew at night. Of course Village Inn radar made a difference to that view when fitted. Some differed and felt that visible gunfire would make the night fighter break away and find an easier target.

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## stona (Sep 17, 2016)

In early 1944 Bomber Command reminded all Groups that.
_"To teach crews that their primary defence is in the use of their guns is wrong."_
This followed a comparison of losses between various Groups which showed that 5 Group, which interpreted the rules of engagement more aggressively, opening fire on unidentified aircraft not only suffered more 'friendly' fire incidents but also attracted the attention of German night fighters. 1 Group might be a little more aggressive, opening fire on identified targets, but 5 Group whose gunners_ 'seem to shoot with abandon at everything that comes their way' _should be impressed with the importance of positive identification before firing an initial burst.
The point is that, operating at night, stealth in the darkness and, if necessary, evasive manoeuvres were the best defence. Firing weapons, from any position could serve to increase self inflicted losses and always gave away the position of the bomber opening fire. The best defence the bombers had was the Mk I eyeballs of their crews, adding a ventral turret, with all the penalties that would incur, was not a solution, many of the reasons have been given in a post above.

The Manchester did start life with a retractable F.N.21 A ventral turret, but it did not have a dorsal turret. Early Lancaster prototypes and early production aircraft used for trials had various configurations. For example, L7527 had both a dorsal and ventral turret, but one of the recommendations made by the A&AEE during trials was for the deletion of the ventral turret 'being of no practical use' in night time operations. Contrary to the assertion made above (years ago) service Lancasters never had a ventral turret.

Cheers

Steve


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## fastmongrel (Sep 17, 2016)

stona said:


> service Lancasters never had a ventral turret.



I thought the BMkIIs were delivered with ventral turrets were they removed before service.


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## stona (Sep 17, 2016)

fastmongrel said:


> I thought the BMkIIs were delivered with ventral turrets were they removed before service.


Mmm, I'll check when I get a chance.
I replied mostly from memory, only looking up the serial of the trials aircraft mentioned.
Cheers
Steve


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## fastmongrel (Sep 17, 2016)

stona said:


> Mmm, I'll check when I get a chance.
> I replied mostly from memory, only looking up the serial of the trials aircraft mentioned.
> Cheers
> Steve



It was something I read a while ago so could be out of date info.


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## fastmongrel (Sep 17, 2016)

Found this photo whilst looking for Lancaster ventral turrets. A Wellington with the Dustbin turret lowered it must have knocked a lot off the cruising speed.


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## stona (Sep 18, 2016)

I have found some evidence that about the first 40 Mk Is (Manchester conversions) were factory fitted with the ventral turret. I can't find much evidence of it in pictures of these aircraft at the first Lancaster squadrons (Just one picture which might show one, they are not always easy to see when retracted), so I suspect it was removed, as recommended by the A&AEE.

I have found pictures of some Mk IIs with both the ventral turret and bulged bomb bay doors fitted, so some at least retained this turret for a while.

The turret ring fitted between frames 24 and 27 (25 and 26 being cut away to fit the turret) and this is also where the H2S installation fitted. The turret ring was replaced by the support brackets for the radar scanner. Mason states that the ventral turret was finally deleted with the introduction of H2S, the two being mutually exclusive.

Cheers

Steve


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## varsity07840 (Sep 18, 2016)

T Bolt said:


> 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!


The lower turret on early B-24Ds was the Bendix, also used on the B-25B through early B-25Gs.


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