Out of the Big Three WW2 bombers (B-17, B-24, Lancaster), was the Flying Fortress the most redundant?

[JDCAVE]

Snowygrouch started this informative thread on bomber Armament.

British WW2 Heavy Bomber Armament

I "lost" this file for years because it has an archive title which is nothing to do with the contents. Found it again by accident a few days ago. The file is an Air Ministry file, so, of course is probably a fraction less self critical than it could be, but still will I think really add some...

ww2aircraft.net

Reviewing these images reveals some finds: First the comment "Nevertheless, in the hope that the US .5 guns would be made available to us at some future date..." This implies that they may not have been available. Further simply taking the .303's out and replacing them with .5's is overly simplistic because of changes to CG of the aircraft. The turret would have to be completely revised and there would likely be changes to the airframe, etc. The Rose Turret was equipped with .5 guns, but Also, while the 20 mm cannon were tested, they completely through the CG out of wack. Lazy I realize but here is some useful points made in the wiki article on the Rose turret, and I believe the Wiki article references the same report as Snowygrouch posted..

Rose turret - Wikipedia

en.wikipedia.org

Review of the article shows the difficulties of changing technologies and the delays that result. We should be mindful of that before we just issue some of blanket statements about the inadequacies of the .303 turrets: It was well known and there were efforts to address it but they didn't come in time to make any appreciable difference.

Dad's KB.865 had the Glenn Martin 250 MUG. It required different positioning because of its effects on the CG.

Jim

 

[Shortround6]

Remember your coat!

and chainmail, your coat is not enough protection

 

[Glider]

It is worth remembering that a few Lancaster's had twin 0.5 in the Dorsal position, one example being at Duxford.

 

[Jabberwocky]

The Browning .50 caliber machine gun was a great choice!

Not so great when the bombers were being designed. The M2 of 1936 is not the M2 of 1940. The AN/M2 is lighter, faster firing and has better ammunition than its forebears of the mid 1930s.

The US Bureau of Ordnance didn't have the money to get their experimental aerial versions of the M2 into testing until around 1936/37 and it wasn't being mass produced until mid to late 1938.

It had range & penetrating power far in excess of the .303 and it could be loaded as ball, AP, tracer, or explosive tipped.

No 'explosive tipped' M2 Browning ammunition for WW2. The M2 did have M8 API from mid war onward and some straight incendiary, but not a HE round.

True, the 20mm packed a harder punch but those cannons had a slower rate of fire and the aircraft could not carry as much ammo.

Which is exactly the same argument that the British made for the .303 vs the .50.

A 4x .30 turret had three times the rate of fire of a 2x .50 turret, carried much more ammunition per gun and weighed anywhere from 140 to 300 lbs less, depending on installation.

Look at the P-47 with 4ea .50 cal in each wing! Patton said he could always tell when they arrived in a place that had been worked over by Thunderbolts- there were holes in the concrete.

I've fired AP ammunition out of a M1 Garand which put a hole in a 4 inch concrete wall.
Yes, the M2 was a good gun (with very good ammunition), but it wasn't the be-all and end-all of aerial armament. It wasn't even the best aerial HMG of the war (that would be the UB).

 

[manta22]

Not so great when the bombers were being designed. The M2 of 1936 is not the M2 of 1940. The AN/M2 is lighter, faster firing and has better ammunition than its forebears of the mid 1930s.

The US Bureau of Ordnance didn't have the money to get their experimental aerial versions of the M2 into testing until around 1936/37 and it wasn't being mass produced until mid to late 1938.



No 'explosive tipped' M2 Browning ammunition for WW2. The M2 did have M8 API from mid war onward and some straight incendiary, but not a HE round.



Which is exactly the same argument that the British made for the .303 vs the .50.

A 4x .30 turret had three times the rate of fire of a 2x .50 turret, carried much more ammunition per gun and weighed anywhere from 140 to 300 lbs less, depending on installation.



I've fired AP ammunition out of a M1 Garand which put a hole in a 4 inch concrete wall.
Yes, the M2 was a good gun (with very good ammunition), but it wasn't the be-all and end-all of aerial armament. It wasn't even the best aerial HMG of the war (that would be the UB).

I have disassembled an explosive-tipped .50 cal bullet. They definitely existed but I don't know their designation. Your .50 cal versus the .303 pea-shooter argument is not convincing.

 

[Shortround6]

and it wasn't being mass produced until mid to late 1938.

and this rather depends on one's definition of mass produced. Yes their is a defense between even a few hundred a year and tool room samples.

1940..........................5155 guns
1941......................49,479 guns
1942...................347,492 guns
1943...................641.638 guns
1944...................677,011 guns
1945...................239,821 guns

This is for ALL .50 cal guns, Air, sea and ground, including the water cooled AA guns. It was possible to build a water cooled gun on an AN/M2 receiver if you had all the extra parts. Most of the differences were in the barrel and barrel and barrel jacket. The rate of fire was dependent on the spring/s and buffer (?).

This was both a strength of the M2 and part of it's weakness. The US only had to supply one main gun and parts and ammo for the aircraft, the army and to the navy. It may not have been as ideal as some guns but by 1942 it worked (mostly) and there was not shortage of guns, parts or ammo.

The M2 did have M8 API from mid war onward and some straight incendiary,

And the M8 API was not a very good incendiary, it did work somewhat as an indicator if the shooter was hitting because it often gave a flash on impact. All you had was little bit between the AP core and the Jacket. Advantage was that as the war went on over 80% of the belt was API. total amount of incendiary wasn't too bad compared to guns with 30-40% of the ammo being incendiary and rest AP and some tracers mixed in.
Late war you had some new incendiary on a trial basis. Dragondog's father may have used some some and it was pretty scary stuff, for the guys firing it.

 

[PAT303]

Minor improvements to be sure, but I'd be willing to bet that when you're fighting for your life at 25,000 feet, you'll take every improvement, no matter how minor.

I would yes and sitting upright in a natural position with four .303's in front of me in a well designed turret with excellent visibility and wide angles of fire would in my opinion be better than two .50's in a not so well designed mount with limited visibility and traverse, it's still going to be extremely difficult to hit a fighter in either but for me the Lancaster turret with four guns loaded with lots of tracer would definitely be the pick of the two .

 

[PAT303]

Your .50 cal versus the .303 pea-shooter argument is not convincing.

You might want to tell all the German airman over southern England in 1940 that the .303 is a pea shooter.

 

[Thumpalumpacus]

I would yes and sitting upright in a natural position with four .303's in front of me in a well designed turret with excellent visibility and wide angles of fire would in my opinion be better than two .50's in a not so well designed mount with limited visibility and traverse, it's still going to be extremely difficult to hit a fighter in either but for me the Lancaster turret with four guns loaded with lots of tracer would definitely be the pick of the two .
View attachment 708913
View attachment 708914

Right, the Lanc's tail-turret was cool, job well-done. B-24 had the same advantages you mention except rate of fire compared to the B-17's tail-mount. Now let's look at dorsal, belly, and nose? I think the -17 gets the first two right, the Lanc gets the last right. The -17's nose armament was its weak spot in earlier iterations, and even the -G model's workaround had nothing on the Wellington or Lanc's turret, imo.

The German fighters are still gonna need more armor against the heavier slugs thrown at them. So while mountings matter, I still think the original question of why not a .50 is valid, at least once the problems got ironed out. The move to heavier armament in fighters speaks to this as well.

Of course J JDCAVE makes good mention of not wanting to change designs in the middle of a production run, but rather, sticking with what you've got. That works both ways when we compare these bombers and their armament, but America had the luxury of greater industrial resources.

 

[PAT303]

Look at the P-47 with 4ea .50 cal in each wing! Patton said he could always tell when they arrived in a place that had been worked over by Thunderbolts- there were holes in the concrete.

Well I find this statement hard to believe because apparently Thunderbolts knocked out Tigers, none of the lesser tanks mind you but Tigers by bouncing .50 cal rounds off the cobblestone roads into their bellies, so the .50 cal couldn't punch holes in concrete because they bounced off it, unless the myth of .50's knocking out armor is not true?.

 

[PAT303]

The German fighters are still gonna need more armor against the heavier slugs thrown at them. So while mountings matter, I still think the original question of why not a .50 is valid, at least once the problems got ironed out. The move to heavier armament in fighters speaks to this as well.

My argument is I don't think it really matters what you have because hitting your target is the single biggest problem. I'd image having four .303's @ 1150 round a minute each with every 5th one a tracer would be the better option regardless of on target effect because having so many tracers going out allows you to at least know were your rounds are going, if you read up on flyers from ww2 to the middle east the sight of tracers seeking you out was the biggest deterrent, there is a good interview with an Argentinian pilot from the Falklands who said the MAG 58 tracers from the ships was the thing he remembers the most, not the missiles. Ultimately it was proven that bombers could not and did not survive without not just close fighter escort but operations taken by the likes of 2TAF and 8TH AF P47's bombing airfields, orbiting fighter bases, fuel depots and supply lines long before the guns started firing.

 

[33k in the air]

It is worth remembering that a few Lancaster's had twin 0.5 in the Dorsal position, one example being at Duxford.

Later Lancaster X production had a Martin dorsal turret with two .50-cal MGs, while a small number (about 180 by war's end, according to Harris' Despatch on War Operations,) of Lancaster I/III had a tail turret with two .50-cal MGs.

I would yes and sitting upright in a natural position with four .303's in front of me in a well designed turret with excellent visibility and wide angles of fire would in my opinion be better than two .50's in a not so well designed mount with limited visibility and traverse, it's still going to be extremely difficult to hit a fighter in either but for me the Lancaster turret with four guns loaded with lots of tracer would definitely be the pick of the two.

Something to note about that Lancaster rear turret is that gunners often removed that center perspex panel, as without that panel in place it provided the gunner clearer vision and allowed him to lean forward and look down to some extent. Removing that perspex, of course, left the turret open to the outside air.

Some crews felt the most important function of the rear gunner was not in shooting back at the enemy, but in providing early warning to the pilot of an approaching night fighter so that evasive action could be taken.

 

[PAT303]

Later Lancaster X production had a Martin dorsal turret with two .50-cal MGs, while a small number (about 180 by war's end, according to Harris' Despatch on War Operations,) of Lancaster I/III had a tail turret with two .50-cal MGs.

The rose turret

 

[JDCAVE]

It is worth remembering that a few Lancaster's had twin 0.5 in the Dorsal position, one example being at Duxford.

Yes, but not a lot. As mentioned above, KB.865 was one of the first to be equipped with that, and it was first operational with dad and crew, 1-March-1945. Below, KB.865. It's the a/c in the foreground. Note the more forward position of the turret. Photo CND Image Library, Yarmouth Nova Scotia, June-1945

 

[Jabberwocky]

I have disassembled an explosive-tipped .50 cal bullet. They definitely existed but I don't know their designation.

A WW2 vintage round or a modern round? To the best of my knowledge, the US didn't adopt a 'explosive-tipped' .50 round until the mid 1980s (and even then, by acquiring a foreign developed round).

Standard .50 cal rounds at the beginning of the war were the M2 ball, M2 AP and M1 tracer. Typical belting was 2 ball - 2 AP - 1 tracer

A new M1 incendiary round was introduced during 1942, as was the M2 tracer. These largely replaced the M2 ball and the M1 tracer in belt configurations. The M10 tracer was introduced a little later than these, although I can't find an exact date of service entry at the moment, and rapidly replaced the M1 tracer.

In 1943 the M8 AP-Incendiary and M20 AP-Incendiary-Tracer were developed, with both introduced sometime around very late 1943 or early 1944 (EDIT: Tony Williams gives "Spring 1944" for M8 service entry). These basically replaced everything else except for M2 AP. Standard belt configurations were typically comprised of AP, API and API-T, although it seems that incendiary rounds were more favoured in the PTO (possibly because of a lack of armour on Japanese aircraft).

There was also the M23 Incendiary round, which didn't enter service until just before VE Day.

Your .50 cal versus the .303 pea-shooter argument is not convincing.

It's not me that was making the argument, it was the RAF.

 

[JDCAVE]

Of course J JDCAVE makes good mention of not wanting to change designs in the middle of a production run, but rather, sticking with what you've got. That works both ways when we compare these bombers and their armament, but America had the luxury of greater industrial resources.

I don't think it was because they didn't want to. It was because they were unable to do so. Harris was very disappointed with the Air Ministry (of course) because of their inability to put together a better defensive fire power. Harris would be the first to agree that the 303 guns were insufficient and aircrew were lost as a result.

Jim

 

[Thumpalumpacus]

My argument is I don't think it really matters what you have because hitting your target is the single biggest problem. I'd image having four .303's @ 1150 round a minute each with every 5th one a tracer would be the better option regardless of on target effect because having so many tracers going out allows you to at least know were your rounds are going, if you read up on flyers from ww2 to the middle east the sight of tracers seeking you out was the biggest deterrent, there is a good interview with an Argentinian pilot from the Falklands who said the MAG 58 tracers from the ships was the thing he remembers the most, not the missiles.

Are you saying that American bomber gunners didn't have tracers in belt? I've been under the impression that they did load tracer, perhaps not the 1:5 ratio that American fighters normally did. Did British bombers use that 1:5 ratio as you suggest? Direct answers to both questions would be appreciated.

Ultimately it was proven that bombers could not and did not survive without not just close fighter escort but operations taken by the likes of 2TAF and 8TH AF P47's bombing airfields, orbiting fighter bases, fuel depots and supply lines long before the guns started firing.

Of course, the German fighters weren't defeated until Doolittle authorized sweeps and strafing after a mission.

 

[JDCAVE]

...but for me the Lancaster turret with four guns loaded with lots of tracer would definitely be the pick of the two... .

Except that the tracer had poor ballistics and tumbled (Basil Dickens ORS). It was discontinued in February 1945. From the 6-Group end of war "Historical Review No 6 RCAF Heavy Bomber Group European Theatre. Appendix to the 6-Group ORB

Jim

 

[JDCAVE]

Okay! So this is the definitive source on the debate between the 303 and the 50 caliber turrets. Harris's Depatch on War Operations 1942-1945.

Jim

 

[33k in the air]

Are you saying that American bomber gunners didn't have tracers in belt? I've been under the impression that they did load tracer, perhaps not the 1:5 ratio that American fighters normally did. Did British bombers use that 1:5 ratio as you suggest? Direct answers to both questions would be appreciated.

Tracers were removed as the war progressed, as the tracers actually resulted in poorer accuracy due to the optical illusion they created (the 'cut back' effect).

See the video "Why WWII Bombers Eliminated Tracers in their Ammo Belt Mixes" from the WWII US Bombers channel on YouTube, which cites the wartime documentation on the subject. (In the description box for the video there is a link to a Google Drive from which the documents shown can be downloaded.)