How useful actually were ventral turrets and gun gondolas?

[pootis]

The US started with remote control ventral turrets with the B-17 and a hole in the floor with an MG for the B-24, then moved to crewed ventral turrets on heavy bombers relatively early on. In mid 44 the 8th air force started removing the ventral turrets off their bombers though. If and what style of ventral gun the B-25, B-26 and A-26 got seems to be mixed.

The Germans seemed to prefer using a rear facing ventral gondola on all their mediums and few heavies that reached service, although remote ventral turrets appeared on some of their late war prototypes. Early on single rifle calibre MGs and later on single 13mm MGs.

The UK started with remote control ventral turrets which they weren't happy with, then abandoned any ventral armament due to that bad experience. This led to issues with Schragmusic but i've heard the later fitting of radars largely resolved that issue.

The Soviets put a single ventral rifle caliber MG on all their bombers, although their bombers were mostly limited to tactical and operational level missions rather than deep strategic bombing.
Italy and Japan never seemed to do much with their bombers.

Ball turrets seem to give the most firepower at the cost of the most drag, no ventral turret obviously has no drag associated and no ventral firepower. Gondola mounts seem to fall in between.

 

[EwenS]

The RAF had a series of manned under fuselage turrets dating back to the 1930s. Initial turrets were unpowered, later ones powered.

British ventral power turrets actually fitted to service aircraft:

Boulton Paul Type K Mk.I and II equipped with 2 x .303 Brownings, fitted to Handley Page Halifax Mk.I and IIs and Armstrong Whitworth Albemarle prototype only.

Bristol Beaufort Nose Rear Defence Turret fitted with a single .303 Browning fitted under the extreme nose.

Bristol Type B.13 armed with 2 x .303 Brownings, fitted to the Bristol Buckingham in rear facing gondola.

Nash & Thompson FN.17 fitted with 2 x .303 Brownings and mounted on Armstrong Whitworth Whitley Mks I, II, III and IV.

Whitley III K7183 Retractable Dustbin Turret May 1938 | World War Photos

Whitley III K7183 Retractable Dustbin Turret

www.worldwarphotos.info

Nash & Thompson FN.21 and FN.21A fitted with 2 x .303 Brownings and arming Avro Manchester Mk.I.

Mid-Lower Turret

Lancaster Archive

www.lancaster-archive.com

Nash & Thompson FN.25 fitted with 2 x .303 Brownings arming Vickers Wellington Mk.Ia.

Nash & Thompson FN.64 fitted with 2 x .303 Brownings arming Avro Lancaster Mk.I and II.

View: https://www.youtube.com/watch?v=QV6XjOdGCy4

There were experimental turrets designed by Boulton Paul, Bristol and Nash & Thompson, which were trial fitted only and did not enter service.

The Handley Page Heyford ventral gun emplacement, named the Dustbin for obvious reasons was not a powered turret.

Handley Page Heyford - Wikipedia

en.wikipedia.org

There was also a hand worked 0.5in under fuselage mount fitted to some Halifax III.

When it comes to the USAAF and the B-24 the situation is more complicated. By 1944 aircraft were passing through Modification Centers in the US to fit them out to meet the requirements of each numbered Air Force.

So in the Pacific, those destined for the 5th AF in the South West Pacific generally had the ball turret removed to be replaced by a hand worked 0.5in MG. Many for that AF were also lost the heavy tail turret, replacing it with an open hand worked pair of 0.5in MG or a lightweight M-6 "Stinger" turret.

380th BG History -- B-24 Aircraft Types: L Models

The 13th AF in SWPA and 7th AF in Central Pacific generally retained the ball turret on their B-24s.

 

[Gilder]

A number of Coastal Command B24's were fitted with a British quad 303 rear turret but I don't know which type.

 

[EwenS]

A number of Coastal Command B24's were fitted with a British quad 303 rear turret but I don't know which type.

Some RAF Liberator II/III/V and a few early Mk.VI received the Boulton Paul Type E tail defence turret as also fitted to the Halifax.

Some RAF Liberator II/III/V also received the Nash & Thompson FN55 Beam Defence mount. This was a twin 0.303in mount with the gunner sitting to the rhs of the guns controlling them via V shaped handle. Fitted in place of the beam 0.5in. The mount was enclosed with glazing.

There was also a Nash & Thompson FN54 with 2 x 0.303in in an undernose position on Blenheim IV. Not much used

 

[Gilder]

Many thanks in particular the second point. I have seen film taken inside RAF Liberators in the Far East and in the background you could clearly see a twin mount of a 303 but I could never track down what it was. The other thing I noticed was the position of the gunner who had quite a sophisticated sight, far in advance of the ring and bead site often seen in US bombers.

Thanks again

 

[MikeMeech]

Many thanks in particular the second point. I have seen film taken inside RAF Liberators in the Far East and in the background you could clearly see a twin mount of a 303 but I could never track down what it was. The other thing I noticed was the position of the gunner who had quite a sophisticated sight, far in advance of the ring and bead site often seen in US bombers.

Thanks again

Hi
Do you mean gunsights like the following:

Extracts from 'British Aircraft Armament Volume 2: RAF Guns and Gunsights from 1914 to the present day.' by R Wallace Clarke. 'Volume 1: RAF Gun Turrets from 1914 to the present day.' will also give you much information on British used under turrets, if you wish to research further.

Mike

 

[Greyman]

The UK started with remote control ventral turrets which they weren't happy with, then abandoned any ventral armament due to that bad experience. This led to issues with Schragmusic but i've heard the later fitting of radars largely resolved that issue.

The only remote systems the British had were still in the prototype stage at the end of the war. These were the RAE system (electric setup in a Lancaster) and the Vickers-Armstrong system (electric/hydraulic setup in a Windsor).

Under armaments were generally used in any daylight bombers that could use them. Blenheims, Bostons, Mitchells, etc.

The early retractable 'dustbin' turrets, FN.17 and FN.25 (used in the Wellington and Whitley) reduced performance too much and were quickly done away with. The later BP 'R' and FN.64 under turrets (used in the Stirling, Halifax, and Lancaster) were fine. The difficulty in seeing below the horizon vs. the advantage a night fighter had in the opposite position made them not worth carrying, especially when the spot was needed for H2S radar.

FN.64s were also used in Mitchells, and the RAF replaced as many Bendix turrets as they could, despite the weaker .303 armament.

There was also a Nash & Thompson FN54 with 2 x 0.303in in an undernose position on Blenheim IV. Not much used

Do you have any figures on this? It was my understanding there was a 100% requirement for FN.54s in 2 Group and Middle East Blenheims -- deliveries starting at some point 2nd quarter 1941.

I could be wrong, but I think the Blenheim V needed the FN.60 in position in order to fly (for CG reasons). The Blenheim IVs could (and did) put them in storage when not required.

 

[pootis]

The only remote systems the British had were still in the prototype stage at the end of the war. These were the RAE system (electric setup in a Lancaster) and the Vickers-Armstrong system (electric/hydraulic setup in a Windsor).

Under armaments were generally used in any daylight bombers that could use them. Blenheims, Bostons, Mitchells, etc.

The early retractable 'dustbin' turrets, FN.17 and FN.25 (used in the Wellington and Whitley) reduced performance too much and were quickly done away with. The later BP 'R' and FN.64 under turrets (used in the Stirling, Halifax, and Lancaster) were fine. The difficulty in seeing below the horizon vs. the advantage a night fighter had in the opposite position made them not worth carrying, especially when the spot was needed for H2S radar.

FN.64s were also used in Mitchells, and the RAF replaced as many Bendix turrets as they could, despite the weaker .303 armament.

Poor wording on my part. I meant the BP R and FN.64 periscope ventral turrets rather than a true remote turret. I didn't realise the RAF kept using those in their day bombers, i thought they were removed because periscope turrets were difficult and unpleasant to use rather than night fighting making them of limited utility. I wonder if had they kept it if it would've still been an effective deterrent against Schragmusic? Given Schragmusic required a nightfighter to fly directly below the bomber for an extended period to be aimed properly as i understand it.

 

[EwenS]

Do you have any figures on this? It was my understanding there was a 100% requirement for FN.54s in 2 Group and Middle East Blenheims -- deliveries starting at some point 2nd quarter 1941.

I could be wrong, but I think the Blenheim V needed the FN.60 in position in order to fly (for CG reasons). The Blenheim IVs could (and did) put them in storage when not required.

Are you sure we are talking about the same mount, because there does seem to be some confusion around about the designations of Blenheim under nose mounts.

This is the FN54 as I understand it and as it appears in "British Aircraft Armament" Vol 1 on gun turrets. A rearward firing mount contained in an angular metal structure controlled by a periscope sight. Traverse 20° each side, elevation +7 / -17°,weight 90lbs, the ammunition boxes holding 1,000rpg being contained in the "box".

The above aircraft was from 13 OTU which used the Blenheim from Nov 1940 to April 1944, latterly alongside Mitchell's and Mosquitos.

There was also what is usually described as an "under defence mount" designed by Bristol, contained in a clear perspex blister with one rearward firing 0.303in. The Blenheim mount was similar to, if not identical with, that employed on the Beaufort. The photographic evidence I've seen shows it to be far more common than the FN54.

The Beaufort mount had traverse 15° each side, elevation +0/-25° with just 200rpg. It was controlled by the gunner lying on his belly in the nose facing forwards using a mirror aligned on a ring and bead sight.

The FN60 turret in the Blenheim V was effectively a hydraulically powered version of the FN54 with a modified fairing to contain the control gear. I can't comment about any CG issues.

 

[varsity07840]

The US started with remote control ventral turrets with the B-17 and a hole in the floor with an MG for the B-24, then moved to crewed ventral turrets on heavy bombers relatively early on. In mid 44 the 8th air force started removing the ventral turrets off their bombers though. If and what style of ventral gun the B-25, B-26 and A-26 got seems to be mixed.

The Germans seemed to prefer using a rear facing ventral gondola on all their mediums and few heavies that reached service, although remote ventral turrets appeared on some of their late war prototypes. Early on single rifle calibre MGs and later on single 13mm MGs.

The UK started with remote control ventral turrets which they weren't happy with, then abandoned any ventral armament due to that bad experience. This led to issues with Schragmusic but i've heard the later fitting of radars largely resolved that issue.

The Soviets put a single ventral rifle caliber MG on all their bombers, although their bombers were mostly limited to tactical and operational level missions rather than deep strategic bombing.
Italy and Japan never seemed to do much with their bombers.

Ball turrets seem to give the most firepower at the cost of the most drag, no ventral turret obviously has no drag associated and no ventral firepower. Gondola mounts seem to fall in between.

The original B-24D ventral armament was the Bendix retractable remote control turret. It was removed and replaced by a hand held "tunnel gun".

 

[varsity07840]

The RAF had a series of manned under fuselage turrets dating back to the 1930s. Initial turrets were unpowered, later ones powered.

British ventral power turrets actually fitted to service aircraft:

Boulton Paul Type K Mk.I and II equipped with 2 x .303 Brownings, fitted to Handley Page Halifax Mk.I and IIs and Armstrong Whitworth Albemarle prototype only.

Bristol Beaufort Nose Rear Defence Turret fitted with a single .303 Browning fitted under the extreme nose.

Bristol Type B.13 armed with 2 x .303 Brownings, fitted to the Bristol Buckingham in rear facing gondola.

Nash & Thompson FN.17 fitted with 2 x .303 Brownings and mounted on Armstrong Whitworth Whitley Mks I, II, III and IV.

Whitley III K7183 Retractable Dustbin Turret May 1938 | World War Photos

Whitley III K7183 Retractable Dustbin Turret

www.worldwarphotos.info

Nash & Thompson FN.21 and FN.21A fitted with 2 x .303 Brownings and arming Avro Manchester Mk.I.

Mid-Lower Turret

Lancaster Archive

www.lancaster-archive.com

Nash & Thompson FN.25 fitted with 2 x .303 Brownings arming Vickers Wellington Mk.Ia.

Nash & Thompson FN.64 fitted with 2 x .303 Brownings arming Avro Lancaster Mk.I and II.

View: https://www.youtube.com/watch?v=QV6XjOdGCy4

There were experimental turrets designed by Boulton Paul, Bristol and Nash & Thompson, which were trial fitted only and did not enter service.

The Handley Page Heyford ventral gun emplacement, named the Dustbin for obvious reasons was not a powered turret.

Handley Page Heyford - Wikipedia

en.wikipedia.org

There was also a hand worked 0.5in under fuselage mount fitted to some Halifax III.

When it comes to the USAAF and the B-24 the situation is more complicated. By 1944 aircraft were passing through Modification Centers in the US to fit them out to meet the requirements of each numbered Air Force.

So in the Pacific, those destined for the 5th AF in the South West Pacific generally had the ball turret removed to be replaced by a hand worked 0.5in MG. Many for that AF were also lost the heavy tail turret, replacing it with an open hand worked pair of 0.5in MG or a lightweight M-6 "Stinger" turret.

380th BG History -- B-24 Aircraft Types: L Models

The 13th AF in SWPA and 7th AF in Central Pacific generally retained the ball turret on their B-24s.

 

[EwenS]

The original B-24D ventral armament was the Bendix retractable remote control turret. It was removed and replaced by a hand held "tunnel gun".

While the Bendix turret may have been the first ventral armament on the B-24D it was only installed from the 77th aircraft off the production line. After 287 aircraft had been produced with this turret a switch was made to a single hand operated 0.5in with the B-24D-15 block. The Sperry ball turret was introduced on the B-24D-140-CO.

 

[Greyman]

Are you sure we are talking about the same mount, because there does seem to be some confusion around about the designations of Blenheim under nose mounts.

No I'm refering to the F.N.54 – did some reading to firm up some details ...

During a conference on 6 November 1939, Bristol agreed to design an installation involving a 'dished' escape hatch panel, firing aft, for the under defence of the Blenheim.

By 17 December these were being made and it was anticipated they would be available in five weeks.

The A&AEE issued their report on this 'escape hatch mounting for Blenheim under defence' on 15 January 1940. They concluded it was satisfactory provided some modifications to the design were carried out by Bristol.

Production order for 1,100 sets was underway in February with 50 sets per week promised by the third week of February.

As of 28 June 1940 'nearly all units in Bomber Command' were completed fitting the single-gun 'escape hatch' mounting.​

-----

The F.N.54 turret (aka two Browning 'bath' under mounting) set to be incorporated into Rootes Blenheim production line mid-August 1941.

Apparently 50 sets were delivered by 22 February 1941.

As of 9 June 1941 50 sets were given to Bomber Command and all production was being used for tropicalised Blenheims. 106 delivered before May. 40 delivered in May and 100 promised for June.

15 Nov 1941 2 Group HQ said the F.N. 54 mounting was not required for night operations (their current role), but daylight operations may resume, and 18 sets per squadron were required (i.e. 180 sets). Since the Group reported holding 384 sets, they asked Bomber Command HQ how to dispose of the extra 205 sets, as well as the numbers retained as the changeover to newer aircraft progressed.

Cancellation of further F.N.54 deliveries was arranged two days previous.

Note from Maintenance Command (I believe), 1 January 1942 -- emphasis mine:

"It is understood that No.2 Group are not entirely satisfied with the position of the mounting on the aircraft, as it results in loss of performance, and for this reason it is not being fitted in all aircraft in accordance with the classification of the modification by which it was introduced ... It is further understood that No.2 Group are endeavouring to fit the mounting in a new position which will not affect performance* ... "​

*this strikes me as a CG issue, as 2 Group figured if they could reposition the mounting it would solve the issue. Not enough info to be sure though, certainly ...

29 January 1942 policy was still to provision all operational Blenheim IVs with F.N.54 mountings (including OTUs).

7 February 1942 the policy was;

Home Squadrons: all Initial Establishment + Immediate Reserve + 25% reserve (i.e. 25 per squadron)
Overseas Squadrons: all operational aircraft
OTUs: 8 mountings each​

 

[Greyman]

I didn't realise the RAF kept using those in their day bombers, i thought they were removed because periscope turrets were difficult and unpleasant to use rather than night fighting making them of limited utility. I wonder if had they kept it if it would've still been an effective deterrent against Schragmusic? Given Schragmusic required a nightfighter to fly directly below the bomber for an extended period to be aimed properly as i understand it.

No, as I posted earlier, the FN64 was fine. AFDU report conclusions:

The F.N.64 is of considerable value in the defence of a heavy bomber. The view from the periscope is satisfactory and the field of fire adequate for the requirements of present tactics. Use of the sight for purposes of search is tiring for the eyes and it is therefore not considered advisable to man the under turret except during periods of probable danger such as known fighter belts.​

In clear skies, both moonless or moonlit, over land -- an aircraft flying below the horizon relative to his target has a 4x advantage in sighting distance.

IE: a Lancaster looks up and barely sees another Lancaster 1000 ft directly above. That high Lancaster wont be able to see the lower Lancaster unless it closes in to 250 feet. It gets worse when you factor in the smaller size of a German night fighter.

Trying to find that night fighter through a periscope, perspex, or armoured glass is very difficult. I had forgotten about the extended search problems with the periscope sights. A major issue for night bomber defence, certainly.

As EwenS said above there was a mad rush to fit direct-vision panels with hand-held .50s underneath Lancasters and Halifaxes in some squadrons, but H2S eventually took over that real estate.

 

[special ed]

May I submit for consideration these examples, which had very good rearward and side visibility, although a bit breezy.

 

[Antarctica]

RAAF Beaufort gunners I've spoken to say the under-nose blister "mirror sight" set-up made them dizzy & never actually used in service - removed asap. I guess the RAF found the same.

 

[pootis]

May I submit for consideration these examples, which had very good rearward and side visibility, although a bit breezy.

I forgot about dustbins. As i understand it they fell out of favour pre-war and were replaced almost immediately during it because when extended they massively slowed the aircraft.

 

[Just Schmidt]

I forgot about dustbins. As i understand it they fell out of favour pre-war and were replaced almost immediately during it because when extended they massively slowed the aircraft.

At least the Leo 451 kept favouring them.