Effectiveness of Bomber Defensive Armament by Type and Location

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I would just throw in the Mosquito as a point of discussion. De Havilland's plan was for an unarmed bomber using speed for its defensive capability. The Air Ministry (UK) wanted an armed bomber and proposed a turret in the mid upper position just aft of the cockpit, similar to the B-P Defiant set up. Test with a mock up were a disaster, having a serious effect on both speed and handling. In the end, the Series I and II Mk IV, were unarmed and it was the ground speed of the aircraft which kept it out of harm so far as losses to enemy aircraft were concerned. The problem with all bombers is they need to run straight and level (pretty much) to hit the target leaving them vulnerable to AA & fighter attack. these were where the greatest losses occurred. The Fighter/Bomber version had one of the best defensive armament set-ups with the 4 x .303 Browning and 4 x 20mm Hispano MG's. The Rockets were a useful addition to the ground strike/ coastal shipping abilities of the aircraft.
 
Darthtabby said:
A A.G. Williams Fighter escorts requiring vastly less rounds to down an enemy plane isn't hugely surprising. I'd be a bit cautious about reading too much into that comparison though. I've heard that shipboard AA didn't down that many enemy aircraft but did help make their attacks less effective. I wonder if bomber defensive armament might have offered similar benefits by placing additional stress on attacking fighter pilots, thus reducing the opportunities for easy shots.
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Yes, that's a fair point. German fighters were distracted by coming under fire from bombers, especially if they could see the incoming bullets - which is why tracer ammo was especially popular among US bomber crews. There was even a special loading for bomber guns consisting of extra-bright tracers to take advantage of this.
 
A.G. Williams said:
Yes, that's a fair point. German fighters were distracted by coming under fire from bombers, especially if they could see the incoming bullets - which is why tracer ammo was especially popular among US bomber crews. There was even a special loading for bomber guns consisting of extra-bright tracers to take advantage of this.
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'Cept they couldn't see the incoming bullets. That's based on the problem with light AAA that Friedman cites in Naval Anti-Aircraft Guns & Gunnery. The body of the projectile blocks with flare, which barely extends past the base of the projectile.
 
elbmc1969 said:
'Cept they couldn't see the incoming bullets. That's based on the problem with light AAA that Friedman cites in Naval Anti-Aircraft Guns & Gunnery. The body of the projectile blocks with flare, which barely extends past the base of the projectile.
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Not so, it seems. The History of Modern US Small Arms Ammunition, Volume II, contains a detailed description of the development of extra-bright .50 tracer known as the "Headlight". The whole concept of the design was to boost the visibility of the tracer from the front in order to distract the German fighter pilots. Initial work involved holes drilled into the side of the tracer compartment but experimentation showed that this was not necessary, the right quantity of the right tracer material was three times more brilliant than a standard tracer. They eventually selected the T1E1 bullet design, which "was more readily visible, especially from the front" and this was standardised as the M21. During 1943-44 over 7 million rounds were manufactured.
 
Drachinifel had a livestream on YouTube yesterday with Jonathan Parshall, At one point a question about the effectiveness of U.S. anti-aircraft fire in 1942 was raised, and Parshall mentioned the reaction of some Japanese flyers to the amount of AA fire from U.S. carrier groups during the Santa Cruz battle.

The question about AA starts at 1:01:53 into the video.

Midway Naval Chat ft. Jon Parshall
 
SaparotRob said:
I enjoyed watching that yesterday. I got a kick out of Mr. Parshall's not putting up with much "what-iffery".
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There are definitely some very good historical channels on YouTube (and on other topics as well). Lately I've been watching videos from the Battleship New Jersey museum channel. The production quality is a bit rough sometimes, but it's getting better.
 
ThomasP said:
Somewhere on the internet . . . there is a US/UK government sponsored analysis that talks about the effectiveness of the defensive weapons, the different formations used, the different patterns of attack used, day vs night, etc. I do not know if I downloaded it, I will see if I did or if I can find it.

I do not remember all it talked about, but some of what I remember is:

Powered gun turrets were significantly more effective than free-swinging guns. The only location unpowered defensive weapons were effective was in the tail.

Prior to the introduction of the GGS: The .50 cal had a higher probability of shooting down or seriously damaging a Luftwaffe fighter attacking a bomber, if it scored a hit. However, the multiple gun .303 cal turrets, coupled with their higher rates of fire and increased ammunition loads, had a higher chance of scoring a hit. Exactly how effective the .50 cal was vs multiple .303 was difficult to determine as there was not enough specific information.

After the introduction of the GGS: It was clear that the .50 cal became the superior armament for the turrets, with the understanding that for future bombers the 20mm would be a significant improvement over the .50 cal.

In terms of the US vs the UK concepts as to the type of installation: It was found that the UK turrets, for the most part, were superior in terms of reliability to the US turrets. They talked about a number of items in the reliability, maintainability, service life, etc. The only 3 things I remember are:

1. US electric powered turret drives needed to be significantly improved. It was found on operations that a common complaint was the US electric turrets could become inoperative - often before reaching the target area - due to the weather conditions and overuse by the operator when scanning for bogies.

2. While the UK turrets (in particular the hydraulic drive types, whether in US or UK service) were significantly more reliable than the US turrets, the hydraulic type had the disadvantage of sometimes being the source of fires due to the hydraulic fluid being flammable.

3. The electric drive was preferred for future installation, because of weight and simplicity, if the reliability of the electric drive systems could be improved sufficiently.

Though it was clear that the larger caliber weapons were the best choice for future defensive systems, particular if GGS and radar aided FC systems were employed, the supply of sufficient ammunition was more problematic. A reference was made to US bomber crew complaints of running out of ammunition before the attacks were over, sometimes before reaching the target. Early-campaign, it was the tail gun position that usually ran into this situation, but the other turret positions also encountered this problem. Late-campaign - in the bombers that had increased ammunition supply for the tail positions - the situation of ammunition shortage was spread about evenly among the tail, top, and bottom positions. The nose turret was least likely to run out of ammunition.

The UK bombers, particularly the types with the feed track systems supplying ammunition to the tail from large bins in the center fuselage, seldom ran out of ammunition, and later in the campaign the tail turret ammunition was sometimes reduced or carried in a manner that would allow resupply of other turrets. (Note that the above applied to daytime UK operations. Night operations were different enough that they were included in a separate section comparing the day vs night operations.)

The introduction of the nose gun turret on the B-17 and B-24 had almost no effect on the attack methods used by the Luftwaffe, re the number of head-on attacks vs tail attacks only changed by ~2%, from ~43% head-on to about 41% (IIRC). Losses remained essentially the same for the Luftwaffe, as did the number of bombers shot down. This data was from Luftwaffe records and post-war debriefs of Luftwaffe personnel.
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-There was a either a late war or, more probably, early post-war analysis by the USAAF that primarily went into turret/armament design. I came across it when looking for information on the "Cheyenne" tail gun position of later B-17s. I believe that there was also a discussion of handheld guns, particularly chin (B-17) and waist, going into the differences between B-17/24, B-25 and B-26. I think I was disappointed that there was no comparison to other, particularly USN PB4Y, turrets and/or gun positions.
-I do not recall that the survey went into relative effectiveness of any/each position.
-I had it in a directory that contained other goodies such as a list of all(?) US WW2 reciprocating aircraft engines with dimensions. Naturally I've changed computers six or a dozen times since then. HOPEFULLY I was smart enough (doubtful) to record the stuff on a CD. I'll look but no promises.
 
A.G. Williams said:
Yes, that's a fair point. German fighters were distracted by coming under fire from bombers, especially if they could see the incoming bullets - which is why tracer ammo was especially popular among US bomber crews. There was even a special loading for bomber guns consisting of extra-bright tracers to take advantage of this.
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I remember reading a Spitfire pilots account of passing a USAAF bomber formation, he was on "withdrawal" to escort stragglers, so passing the box to get to the rear of it. The whole formation is distracting, he said he was well aware that there were 1,000 men with heavy machine guns looking at him and was glad he was on their side, the thought of attacking it was very intimidating. LW pilots knew they could be fired on because they knew the planes they were attacking. Whether by seeing gun flashes from the guns, smoke trails or light from the incendiary rounds they knew they were going into defensive fire. Experienced hands at it could tell them that usually you dont get hit, but I think that is a psychological hurdle that needs to be jumped.
 
KSJ said:
I would just throw in the Mosquito as a point of discussion. De Havilland's plan was for an unarmed bomber using speed for its defensive capability. The Air Ministry (UK) wanted an armed bomber and proposed a turret in the mid upper position just aft of the cockpit, similar to the B-P Defiant set up. Test with a mock up were a disaster, having a serious effect on both speed and handling. In the end, the Series I and II Mk IV, were unarmed and it was the ground speed of the aircraft which kept it out of harm so far as losses to enemy aircraft were concerned. The problem with all bombers is they need to run straight and level (pretty much) to hit the target leaving them vulnerable to AA & fighter attack. these were where the greatest losses occurred. The Fighter/Bomber version had one of the best defensive armament set-ups with the 4 x .303 Browning and 4 x 20mm Hispano MG's. The Rockets were a useful addition to the ground strike/ coastal shipping abilities of the aircraft.
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W4050 was fitted with a dummy turret behind the canopy. Mock guns could be fitted to face fore or aft, or either side.

Another prototype (W4063) was fitted and flew with an operating gun turret. This was the turret fighter prototype, not a bomber.

Some pictures in this thread: Aircraft Mock-Ups
 
ThomasP said:
Powered gun turrets were significantly more effective than free-swinging guns. The only location unpowered defensive weapons were effective was in the tail.
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Excellent post, Thomas, and sticking to the original question. Power turrets, as we know were first put on to aircraft by the British, who believed in the technology, but there was a bit of a caveat to the first bombers entering service with them. Gunnery training suffered as in the mid to late 30s it was little more than what was practised during the Great War and wasn't designed to incorporate the new-fangled technology. This meant that once bombers like the Wellington and Whitley entered service, gunnery accuracy in training actually decreased, which prompted a rethink of gunnery training and centralisation of it, spurred on by the C-in-C Bomber Command Edgar Ludlow Hewitt. It's worth noting that when the US Eighth AF first arrived in the UK gunnery training was done in British skies as US crews had little experience in power turret operation. Eventually, someone saw sense in that the airspace in the USA was a lot larger and less crowded and it began stateside. The US got its turret technology from the British in technology exchanges, the Boulton Paul Turrets influenced Martin in that they were electro-hydraulic, for example and the first US bomber fitted with power turrets was the B-24, which was retrofitted with Boulton Paul turrets, the British Libs being delivered without armament.

KSJ said:
De Havilland's plan was for an unarmed bomber using speed for its defensive capability. The Air Ministry (UK) wanted an armed bomber and proposed a turret in the mid upper position just aft of the cockpit, similar to the B-P Defiant set up. Test with a mock up were a disaster, having a serious effect on both speed and handling.
Click to expand...

The upper position for the turret on the Mosquito was for a night fighter, not defensive armament for a bomber, as Wuzak stated. The Air Ministry did request a turret for the bomber Mosquito, but it was a tail turret and the only trials conducted were paper exercises, which thankfully never amounted to anything more than the production of figures. The prototype was fitted with a dummy for aerodynamic purposes to aid in the development of a turret fighter for a night fighter specification and two prototypes were built and fitted with gun turrets, but the Bristol turret fitted to the aircraft was insufficiently capable of operating at the speeds the Mosquito flew at; it's hydraulic system couldn't produce enough pressure to rotate the turret in flight.
 
Going a bit further into this, I don't know if anyone has produced any comparison between the different bombers and how effective statistically their defensive armament was, it would be interesting and would require a bit of interpretation because of the different environments that different countries' bombers operated within. During the piston-engined interceptor era, power turrets offered greater advantages to unpowered guns because of speed and accuracy of aiming, and apart from the teething troubles with training, they did prove necessary as the Battle of Britain proved that free aimed defensive guns were inadequate defence, but even power turrets had their limitations of course. Higher interceptor approach speeds meant that power turrets couldn't keep up and into the jet age turrets began to disappear altogether, except remote tail turrets, with the exception of the Soviet jet bombers and their Chinese off-shoots, the Tu-16 variants still in production in China are still fitted with remotely operated turrets.

Power turrets introduced complexity and weight however and increased load on the aircrafts' hydraulic systems, which required multiple engine-driven hydraulic pumps, but Boulton Paul turrets were electro-hydraulic and were self-contained, not relying on the aircrafts' hydraulic systems, having their own pumps and reservoirs in case the aircraft's system failed the turrets still operated. The penalty - there always is - was that BP turrets were heavier, but they were easier to operate, being done with a single joystick, which meant one hand was free to clear stoppages etc. Nash & Thompson and Bristol turrets required both hands to operate. Both these types relied on the aircraft's hydraulic systems, but they were lighter. Ideally, fitting as many power turrets as possible in strategic positions is what is wanted, but as mentioned, they add weight, which means that areas, where they are fitted require strengthening and depending on which type of turret fitted, the production of long hydraulic lines running the length of the aircraft, which brings with it various issues.
 
I was going on what nuuumann posted about a dorsal turret being considered for the night fighter version of the Mossie. I would have just left that stellar aircraft alone and thank The Great Aviator Above for receiving such a great plane unasked for.
 
SaparotRob said:
Did someone envisage a Mosquito "turreted night fighter" with a dorsal weapon? Defiant 2.0 as it were?
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Yup, in fact the night fighter spec F.18/40 issued in October 1940 specified fixed gun night fighter but was amended in December 1940 to include a power turret. Obviously, BP issued a tender and the Bristol Beaufighter Mk.V fitted with a BP turret was recommended for production, but being slower than the Defiant it was intended on replacing it never happened, although a couple of these went to night fighter squadrons and were used in combat with inconclusive results. The Mossie turret fighter came about from this in that de Havilland was never offered to tender to F.18/40 but were requested to produce data, bearing in mind that the prototype Mosquito had only just flown for the first time by the time the amendment was made in December 1940. The first prototype of the turret fighter Mossie was the fourth prototype to fly and was eventually converted into the prototype of the T.III trainer. Two turret fighter Mossies were built and for the life of me tracking down photos of these aircraft is well nigh impossible, apart from the usual one of a close up of the aircraft in the hangar. I've only ever seen the one drawing of a turret fighter Mossie, too, and even then, the original source of the drawing said to me that it was defensive armament for a bomber, despite the title saying "DH.98B Turret Fighter"!
 
nuuumannn said:
Of course, the reason why F.18/40 amended with turret armament was never fulfilled was because of the excellent performance of the fixed gun night fighter Mosquito.
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I was just about to quote Macmillan "events dear boy, events"
The Beaufighter entered service as a night fighter in September 1940, just at the start of the night time Blitz. Very early operations were carried out without radar, relying on ground control, searchlights and luck to find their opponents, a very difficult task. Even so, the Beaufighter achieved its first kill on 25 October 1940, without radar.

The first radar kill was achieved on 19/20 November 1940, by F.Lt John Cunningham of No. 604 Squadron. Cunningham would become the best known British night fighter pilot of the war, being given the nickname "Cat's Eyes" Cunningham after attempts to explain his prowess at a time when radar was a top secret.

Bristol Beaufighter

Bristol Beaufighter, development and combat history
www.historyofwar.org

 
pbehn said:
I was just about to quote Macmillan "events dear boy, events"
The Beaufighter entered service as a night fighter in September 1940, just at the start of the night time Blitz. Very early operations were carried out without radar, relying on ground control, searchlights and luck to find their opponents, a very difficult task. Even so, the Beaufighter achieved its first kill on 25 October 1940, without radar.

The first radar kill was achieved on 19/20 November 1940, by F.Lt John Cunningham of No. 604 Squadron. Cunningham would become the best known British night fighter pilot of the war, being given the nickname "Cat's Eyes" Cunningham after attempts to explain his prowess at a time when radar was a top secret.
Click to expand...

Yup, of course, but radar has nothing to do with what we are discussing. We're talking about power turrets, not radar. F.18/40 was amended after these events to incorporate a power turret. This is why the Beaufighter Mk.V was built with a Boulton Paul turret. The performance and capability of the fixed gun night fighter Mosquito negated the need for a turret-armed night fighter, radar or not. The Mossie turret fighter was to be fitted with radar.
 
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