Bomber Defensive Gunnery questions

So, a couple of up front technical questions:

Which of the allied bombers had the most and/or the best defensive armament in the western European theater?

Did all the American bombers use the M2 .50 HMG as on board guns? And did the RAF/RN use the .303? I mean exclusively?

Did any bombers use cannons on board as defensive weapons? Anything esoteric?

Okay, now . ..

Did any bombers shoot down a LOT of axis planes? Which bombers shot down the most axis planes?

Thank you.

 

Hi Hummel,

There are, in my mind anyway, so many permutations of answers to these questions. The variables should probably include an assessment of what they were up against at a particular time and in particular theatres. These two factors alone make it a complex matter.

I would guess at the YB-40 variant of the B-17 as meeting your most / best criteria. It may also meet the esoteric criterion. I am yet to come across accounts of cannon-as-defence in Allied bombers.

I think the .5 MGs were standard fare on American bombers but recall that in some earlier B-17 models, the nose guns in the plexiglass section were .303 because of recoil and mounting factors.

As far as my limited knowledge goes, I think the RAF bombers remained exclusively .303, save for twin fifties in a later rear turret employed toward the end of the European air war in Lancasters and Mk III Halifaxes. It was known by a few names but most commonly, I think, as the Rose turret. This often incorporated AGLT (automatic gun laying turret) technology.

Michael

 

that's a good question, it probably deserves a book of its own.
The flying forts and liberators were the best armed bombers of the war. No other nation had anything close to the .50 caliber for arming their bombers. The Germans armed their bombers exclusively with rifle caliber machine guns (usually the mg 34) and its safe to say these could probably be considered ridiculously underarmed. With the 50 caliber, particularly in the Pacific against the fast but flimsy japanese zero , one solid hit could bring down an enemy fighter.

The b17 in particular, had defensive armament carefully designed to minimize uncovered areas. Even so bomber gunners did not shoot down as many fighters as you might think. German and Japanese fighters knew they would be shot at, and planned accordingly. towards the end the favored German tactic was a head on attack. This minimized the number of guns that would be shooting at them, and placed the most vulnerable part of the aircraft (the pilots) in the fighter's sights. Closing speeds were on the order of 400-600 mph combined so this gave the fighters only a very short time to shoot. Conversely it also gave the bomber gunners only a second or two to take a shot at the fighter flashing by. The germans also often attacked in the middle of the formation, so any bombers shooting at them were just as likely to wind up shooting at another American bomber.

The defensive armament was powerful and highly respected. In the late war period, the Germans came up with large rockets, that were lobbed from an ME 110 into the middle of a bomber formation. They then simply blew up with a shotgun effect. These rockets downed many bombers at relatively little cost to the attackers (The rockets were launched from well out of effective machine gun range).

 

Jan J. Safarik: Air Aces Home Page

 

Did any bombers use cannons on board as defensive weapons?

Yes, as 20mm weapons were considered as cannons
B-29/Mistubishi G4M/Heinkel He 177 are a few examples of bombers equipped with 20mm weapons.

Example: G4M3 Model 34 Ko = 1 tail 20mm cannon + at least 2 side 20mm cannons

Note: 20mm Cannons had a longer range and far more hitting power than even 12.5 machine guns

As sidenote and for the ones who love 'big guns':
The B-25G and B-25H: Had a 75 mm (2.95 in). Although it was often replaced by .50 machine guns.

The Ju 88 P serie: Especially the P3 had 4 × 37 mm-> if you want unusual 'big guns', there was a thread about that:
http://ww2f.com/information-requests/23112-largest-gun-ww2-aircraft.html

 

Half the reason behind the defensive armaments of heavy bombers (and light bombers, for that matter) was not necessarily to shoot the enemy fighters down, but to keep them from getting a clean shot at the bomber; it was more of a deterrent than an actual means of shooting the attacking a/c down. As marc mentioned, bomber gunners didn't really shoot down all that many a/c (in fact, most bomber gunners never shot ANY a/c down), but to keep the enemy fighters from having an easy time of it.

 

I believe there was also a YB variant of the B-24. Not sure which had the most firepower. On the otherhand one could argue they were no longer bombers as they had replaced their bomb load with guns and ammo. Indeed one of the problems they had is they couldn't keep up with the bombers after the bombers dropped their bombs. Too much wieght was in guns.

 

yes as a matter of fact some US B-17 groups experimented with a cannon in the tail position, have seen the pics, too heavy to effectively follow the path of a LW fighter attack and the weight of the unit it was removed.

We have a lengthy section on LW tactics that a couple of us hadded to several eyars ago on this forum, probably in the archiv's so may take a look. the LW chenged tactics often enough and they had to when US escort fighters came into play in late 43 and into spring of 44 and then dominacne in the summer of 44 till wars end. the effectiveness of the 20mm cannon can be discussed the tail turret .50 mg had a longer range than the MG 151/20 as the attacks from LW twin and s/E fighters from the rear in 44 as standard as they set up on a bomber they were already receiving rounds from the bombers tail turret before they could close within the 20mm range and then later if carried the 30mm cannons. The Br 21cm rockets were a joke and a stop gap only they were not effective there was no way of effectively aiming the device except get close enough and hopefully hit something or the fuze explode the rocket unit within the bomber pulk, heavy cannons though longer range and due to weight performance through off the twin seaters pilots aim along with the aerodynamics of using the longer barrel units in the air and firing them.

With the advent of the jet the rear attacks continued as the LW fither pilot only had to contend with the rear gunners position until he flew stright through the line of fire towards the front of the bomber formation and flying out banking whichever direction he could and hopeful he would not be jumped on by packs of P-51's.

 

this has nothing to do with WW2 but perhaps an interesting story. I was in the Air force back in 1980 and a sargeant told me he was in the Phillipines at Kadena Air Base (now closed). He had been ordered to guard some B-52 bombers so he was standing there with his rifle. He would walk around his assigned area but he heard a sound from the tail guns of a parked airplane. He noticed that whenever he moved, the guns moved with him and were pointing right at him all the time, no matter where he stood. Naturally this disturbed him so finally he told an aircraft tech about the ghost tail guns. The tech then explained what it was, that it was not someone playing a prank but a technical issue. And then climbed inside the B-52 and shut off the radar for the tailguns.

 

I think the head on attack was more a mid war tactic, by late 1944 the B-17 and B-24 no longer had that blind spot so the Germans changed tactics again. Head on attacks also required very good pilots, something the Luftwaffe was short of by mid 1944.
The Germans used as defensive armament:
- 7.92 rifle caliber guns (not the MG 34 but the MG 15 and MG 81 that were even faster firing than the MG 42 and used a slightly more powerful cartridge than the land weapons).
- 13mm MG 131,
- 15mm MG 151
- 20mm MG FF and MG 151/20 and some rarer guns like the HS404 and MG 204.

The MG 151 and the 30mm Mk 103 of some late war fighters (it was much too big for a conventional turret) outranged the Browning but the 15mm MG151 was not powerful enough against bombers. The more common MG 131, MG FF, MF 151/20 and MK 108 30mm cannons did not.
BTW there is a book on this subject, Flying Guns WW2 by fellow rogue Tony Williams.

 

Along those lines, a friend of mine used to be an AD on the Connie, and he said the gimballed seeker head on the AIM-9L would track him as he walked across the deck; he said it was a pretty spooky feeling.

 

the head on tactics were used in 1943 along with high side attacks diving down and then into spring of 44 then July 44 when the Sturmgruppen came into being the standard attack was from the rear till wars end, taking out the tail gunners position and almost sitting back tearing the engines apart and cutting off one wing thus the tip over and loss of the bomber, fewer rounds were used so the LW pilot could possibly attack another bomber from the rear with hopeful the same results. The Mk 103 was an issue for ground attack squadrons not single or t/e fighters against bombers the cannon was too slow firing for this useage

 

Hi lwd,

A good point. I agree with your view that it was no longer a bomber in the common sense.

I recall that there was a B-24 equivalent but I cannot find the source.

Michael

 

Couple of points in relation to the topic....

Rear attacks could only be made by experienced pilots. The amount of metal directed at the attacking fighter used to unsettle the younger pilots, so the old hands used to tell them to make rear attacks "with their eyes closed"....

The B-17 formation and defensive armament was specifically designed and /or organised to oppose attacks from the rear. The Luftwaffe developed attacking styles from other angles as a result of experiments conducted with captured American aircraft. They even had a "Flying Circus" School of captured American bombers that flew from base to base, giving LW pilots practice against the big bombers in the best possible manner. Models were used also to show fields of fire for defensive weapons. The 8th AF high command thought that the tight formation would be defense enough to fly unescorted to targets deep inside German airspace. The Luftwaffe soon put to sleep these early theories, and until the advent of the Mustang fighter, a lot of American aircrews paid for this ineffective doctrine with their lives.

One must remember that the American commanders in the Air war over Europe carried on as if they had nothing whatsoever to learn from their British cousins. They insisted on conducting daylight operations over German airspace without first gaining control of that said airspace, an arrogant attitude that cost much blood before the "Little Friends" managed to make their presence felt.

The YB-40 was an operational failure, for the specific reason that it was too slow to keep formation once the rest of the group had dropped their bombs. Bombers that dropped out of formation were sitting ducks for Nazi fighters. The Germans would aim to cut apart these formations so that their twin engined fighters could close in with cannon for the kill. Formations were divided into three seperate units, (High, Middle and Low Squadrons). The Low squadron almost invariably suffered more. Unlike in the movies, once you dropped out of formation it was next to impossible for you to get back in, even if undamaged.

USAAF gunners were in a class of their own for overclaiming kills. When a German fighter was dropped, half the formation would return to make the claim. Tactics varied from the RAAF. USAAF gunners literally filled the air with lead. RAAF gunners preferred crisp bursts at targets that they could see. Speculative shooting was discouraged, partly to conserve ammunition, but mainly to avoid giving their position away at night.

One wonders why the RAAF continued to provide their bombers with 303 machineguns, when the larger 12.7mm (50 calibre) machinegun was clearly a superior weapon. The Pacific provided the best circumstances for operating the B-17 the way it was intended....unescorted. Even with 20mm cannon fitted to the Zeke, it was incredibly tough to knock a B-17 down in the Pacific.

Christopher

 

sorry Chris but your statements are incorrect, from the late spring summer of 1944 all attacks were to be made from the rear regardless of the experience of LW fighter crews single or twin engine. this was standard orders once the rear attack had taken place then the possibility of attacks from all angles could occur this happened as example when my cousin's Jagdgeschwader JG 301 attacked the B-24 groups the 491st shooting down 16 B-24's and then ahead of this US bomber outfit hitting the 445th bg knocking out 5 more B-24's. I have the two bomb group after action reports for this mission on November 26, 1944. In fact I have another 30 mission dated reports detailing the attacks and angles of the pursuing LW fighters, sometimes not quite correct from US eyes.

LW tactic from the rear was given precisely as I stated as to why they did this.

 

No worries Erich....I am basing my comments on an interview I saw for the World At War BBC series....The exact quote goes like this...

"....So, I used to tell the junger pilots, who had no experience, to close their eyes when attacking from the rear."

Anything else you disagree with?

 

Actually, rear attacks as Erich points out are the easiest to make. The closing speed is low, the angle of deflection is near zero so even the most inexperianced pilot can do this. Head on attacks took nerve and pilot experiance to do as you are essentially going to fly into a collision and then through a formation of aircraft as you break off your attack.

The best method to attack bombers is the one the USN worked out before the war. They alone were teaching their pilots deflection shooting. I don't mean just giving them a quick lesson in it but actually making them practice the methods involved. They also designed their aircraft with this in mind. This is the reason the F4F and F6F for example look hunchbacked. Grumman placed the pilot high in the fuselage and sloped the nose away so he could see a target below and ahead of the aircraft and maintain a aimed deflection shot as he closed.
Once the war started the US military in general began to pick up on this and other nations begain to take an interest in this subject as well. Of course, for the Germans and Japanese it became a struggle to just teach their pilots to fly let alone be really proficient. The Soviets likewise never really gave their pilots such refined lessons but rather just cranked out volume.

Anyway, the method was to attack the bomber in either a high (prefered) or low side pass. In both the pilot approached the target bomber on a reciprocal parallel course either above (high) or below (low) to one side of the bomber. So, the fighter was closing from ahead and to one side. This gave the defending bomber's gunners a deflection target closing at high speed making effective defesive fire the hardest to do as the gunner had to take a leading shot with both horizontal and vertical deflection components.
As the fighter drew parallel with the bomber the pilot would turn into his target trying to pick an amidships aiming point and begin to dive (high) or climb (low) in his turn. As the bomber came into the aim of the fighter's guns the pilot would correct for deflection and then open fire on the bomber continuing to turn as necessary to maintain the proper deflection.
This method had the great advantage of giving a maximum amount of target area as well as putting the fire in the most vulnerable parts of the aircraft, the wing roots and center fuselage. Defensive fire the whole time had to be done at a deflection lessening the chances of effective defense.
In head on and tail chase attacks the fighter is closing on an essentially straight line with the bomber making defensive fire much easier to accomplish. But, these attacks take far less skill on the attacking pilot's part to carry out. By 1943 most Luftwaffe pilots lacked the necessary piloting skills and never had the deflection shooting skills to carry out any other attack method. Hence their move to stern chases.....

 

The B-24 equivalent of the YB-40 was the XB-41. A single test model was delivered to Elgin Field for testing on 29 January 1943 but never reached the operational test phase that would have given it the YB designation. The XB-41 program was cancelled, partially because of the negative experience of the YB-40s.

The first nose turret equipped B-24Hs were delivered late June 1943 and were soon in combat in Europe to meet the head-on attack threat. The chin turret equipped B-17s followed shortly.

I believe Erich is correct about orders for rear attacks in 1944, but those orders were not always followed. I have seen 15th AF mission reports showing attacks from other clock positions in the Spring/early Summer of '44.

Due to closure rates, it required a much greater level of pilot experience to successfully prosecute a head-on attack than a rear attack.

 

MC the standard was for the ETO in defense of the Reich in the MTo if we want to call it that you had JG 27 and II./ZG 1 flying the Bf 110G-2 only plus Hungarian Bf 109G-6 units and even JG 302 flying the same. any angle was used from war time diaries later the rear attack in 1944 for the Bf 110G-2 unit and then bank off turn around and attack again if not hampered by the Mustangs of the 15th AF

 

The British stuck with the .303 for several reasons:

First, all of their existing turrets, mounts, etc, used it. To switch in wartime would have been expensive and difficult.
Second, you could carry far more ammunition for that sized weapon giving a bomber more firing time than a larger weapon would. It is not very convienent if your gunners run out of ammo...
Third, the .303 was more that sufficent to distract or scare off many attackers. It takes more than a little determination for a pilot to continue on a run unabaited when his aircraft is taking hits in return.

The French and Japanese both opted for 20mm cannon in many cases as a defensive gun. Good hitting power when it hit. Problem was most of these weapons had limited ammunition both in terms of that loaded on the gun (typically just 60 rounds in a drum) and in reloads (another 3 or 4 drums typically). This means frequent reloads and not much firing time.
The US designed their defensvie guns to have continious belts most of the time. This meant the gunner didn't run out of ammunition until the ammunition ran out. No reloads was a useful thing.
The .50, like the .303 was more than sufficent to cause many attackers to break off before doing much damage. But, the .50 also had the advantage of being longer ranged and having more hitting power.

I think the Germans were the worst off in this respect. All of their defensive systems on most bombers were crammed into the cockpit / crew area of the aircraft at the nose. This gave poor defensive fields of fire in many areas. The use of mainly hand held weapons was also a negative as these are typically less effective than turret mounted ones.
Their choice of various sized guns also presents a problem. One weapon cannot interchange ammunition with others in many cases. This too can be a problem.
Having all the crew in close proximity would also be a liability I would think. A good burst in the right (or wrong depending on how you look at it) place would kill or wound many crewmen and cause a disruption of the entire crew from the hit(s).