Considering the reliability problems with the 20MM and its much smaller ammo loadout perhaps an all .50 HMG approach might have been a more feasible and easily accomplished improvement. Two big advantages the P-38 had was having the firepower concentrated in the nose for a concentrated damage pattern and better targeting at all possible ranges. The second is the large magazines of 500 rounds per gun giving more than 40 seconds or better of firing time. That would have allowed the pilots to fire prolifically and in sustained combats for example long range escort missions. Were these 500 round magazines the largest .50 magazines installed in Allied fighters? Maybe.
Taking another look at the nose armament in the P-38 and the room available maybe the 20MM should have been removed and replaced by as many .50 M2s as could be fitted providing there is still room to give each additional M2 a 500 round magazine. Could the 4 .50s be move back to the fire wall and upward slightly to allow 2 more to be fitted below and forward of them giving a total of 6 HMGs? Could 7 or 8 be fitted and still have room for the large magazines? That would've been quite the concentrated punch having 8 M2s in the nose. Better then the P-47. Even the most well built and heavily armoured Luftwaffe bomber interceptor is not likely to survive a well aimed burst even without the additional benefit of 20MM hits.
Taking another look at the nose armament in the P-38 and the room available maybe the 20MM should have been removed and replaced by as many .50 M2s as could be fitted providing there is still room to give each additional M2 a 500 round magazine. Could the 4 .50s be move back to the fire wall and upward slightly to allow 2 more to be fitted below and forward of them giving a total of 6 HMGs? Could 7 or 8 be fitted and still have room for the large magazines? That would've been quite the concentrated punch having 8 M2s in the nose. Better then the P-47. Even the most well built and heavily armoured Luftwaffe bomber interceptor is not likely to survive a well aimed burst even without the additional benefit of 20MM hits.
Considering the real life P-38 and its various flaws that were slowly rectified over time what ever gains that improving the armament package would've produced was never considered worth interrupting the production lines for. But redesigning only the interior framing of the nose compartment to fit an additional 2 or 3 or 4 Mama Deuces might not have been too big a disruption to production.
That was not the only potential improvement that was deferred either. The Lightning had what must have been the shittiest canopy of all Allied late-war fighters. Why? The P-38s' canopy might have been what the cutting edge of plexiglas technology would permit in 1937 but in 1942 or 1943 when one-piece teardrop shaped canopies were being produced why was the P-38 not fitted with these? Other fighters were. Notably the P-47 and P-51 in 1944. It could not have been that big a job to redesign the canopy so the pilots would gain the benefit of improved visibility and reduced draftiness. But that would have disrupted production.
Well, that was real life. That's why we have alternate history speculation. So we can vent our spleens and resolve all the problems.
That was not the only potential improvement that was deferred either. The Lightning had what must have been the shittiest canopy of all Allied late-war fighters. Why? The P-38s' canopy might have been what the cutting edge of plexiglas technology would permit in 1937 but in 1942 or 1943 when one-piece teardrop shaped canopies were being produced why was the P-38 not fitted with these? Other fighters were. Notably the P-47 and P-51 in 1944. It could not have been that big a job to redesign the canopy so the pilots would gain the benefit of improved visibility and reduced draftiness. But that would have disrupted production.
Well, that was real life. That's why we have alternate history speculation. So we can vent our spleens and resolve all the problems.
That might have been the excuse. I don't buy it. There were comparable (bigger!) changes in the P-47 & P-51, & nobody was screaming--& both of those were, AFAIK, in greater demand in the higher-priority ETO.
Or was Lockheed production such a snafu even at its best the AAF decided not to throw a grenade in it?
That, I might believe.That might have been the excuse. I don't buy it. There were comparable (bigger!) changes in the P-47 & P-51, & nobody was screaming--& both of those were, AFAIK, in greater demand in the higher-priority ETO.
Or was Lockheed production such a snafu even at its best the AAF decided not to throw a grenade in it?
Everybody except the 8th airforce in late 1943 was screaming for more P-38s. Everybody.
It was a complicated airplane with a complicated airframe. Like the Spitfire. Both were an aluminum work of art. But it wasn't as easy to mass produce as for eg. the P-51. North American designed the Mustang in the middle of the war keeping the goal of simplicity of mass production firmly in mind. Lockheed designed the P-38 in 1937 with the idea of they were only building at best 200 or so for the the USAAC over the next few years.
Nevertheless Lockheed did manage to build 10,000 of them.
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Regarding the 8 nose gunned test plane does anybody know what size the magazines where for those 8 M2s? It looks like a very tight squeeze in that nose compartment. Bit blurry though.
I have only seen this and another very low res image from the opposite side for this installation. I have never found any information on how they made it work (if they did) or how much ammo they were able squeeze in per gun. My guess would be considerably less than the 500/gun of the standard installation. Something more like 200-250/gun at absolute most (remember how much space would be lost just with the extra guns and their mounts, not to mention the ejection chutes, etc) and very likely a bit less, with 150-200/gun seeming realistic, so about 14 - 18 seconds of fire-time (7 - 10 bursts I would think) compared to the 45 seconds of time (20-25 bursts likely) with the standard installation.
Sounds like a pretty good assessment to me. I've arrived at the conclusion that 6 HMGs could have been fitted in the OTL P-38 and still have the room for the 500 RPG with a minimal amount of redesign or disruption of ongoing production.
Now whether this would have been any large improvement over the existing armament fit I don't know. By that I mean I don't know if it would have been worth the trouble. Better to improve the reliability of the American built HS 20MM. If that wasn't going to happen then go to the 6 Brownings.
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McPherson
Banned
Or upscale the Browning MG into a true auto-cannon. Paper calculations...
Specifications
Doable? Space-wise the volume is there, but ~350 kilograms mass in the nose. That is a YIKES moment for any aircraft. ~2/5 of a TONNE.
What was the RTL load in the P-38 gun-pack?
2000 rounds of .50 at 4 ounces per round. = 500 pounds.
150 rounds of 20MM at 9 ounces per round = 85 pounds.
And the weight of the guns. 4 M2s = 300 pounds.
And the cannon. 130 pounds.
I get 1015 pounds for OTL P-38. About 585 of that being the ammo. You might want to check my numbers McP. I don't think they are wildly inaccurate but they are estimations.
McPherson
Banned
Add about 100 pounds for frame carriage and the feed ramps. So maybe the quad 20 pack is actually lighter?
Add about 100 pounds for frame carriage and the feed ramps. So maybe the quad 20 pack is actually lighter?
I think having four 20MM cannons concentrated in the nose would be the best armament installation for the P-38. But for these stumbling blocks. There is no way they can be fitted in the nose and still be supplied with (what I would consider) an adequate ammunition load. To do that means a redesign of the gondola. Which might have been a good move but just wasn't going to happen in real life.
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As for the 6 x .50 vs. the OTL Standard Load out, one way of looking at it is to look at their weight of fire per second (assuming you can get 500 rpg in the 6x setup and assuming your 20mm doesn't jam):
For those curious, a 4 x 20mm setup, if you could squeeze 150 rpg in there, would give you 198.73 oz(US)/sec (5633.9 g/sec) for 13.85 seconds. Then you're cooked.
- 6 x AN/M2 .50 Cal. @ 800 rpm = 118.67 oz(US)/sec (3364.24 g/sec) for 37.5 sec.
- 4 x AN/M2 .50 Cal. @ 800 rpm + 1 x A/N-M2 20mm @ 650 rpm = 128.8 oz(US)/sec (3651.42 g/sec) for the first 13.85 sec, then 79.12 oz(US)/sec (2243.01 g/sec) for the next 23.65 sec.
For those curious, a 4 x 20mm setup, if you could squeeze 150 rpg in there, would give you 198.73 oz(US)/sec (5633.9 g/sec) for 13.85 seconds. Then you're cooked.
The trouble with quad 20's isn't the weight. It's the space. The HS.404 / A/N-M2 is about 100 inches long, give or take depending on the specific model and installation, which is why there is only one installed in the P-38, where its receiver (and magazine) rides above the nose-gear compartment. To add more, as @Draconis pointed out, you would need to redesign the nose to allow more space either around or in front of the gear-well (the latter option would potentially upset weight-and-balance, while the former would require a redesign of the entire gondola to allow the required space).
Regarding the weight itself, the P-38 was dry-rated for 2000# ordnance in the nose. As was already pointed out the actual installation may have been a bit less, but this was its rated load in all of the documentation I have found. Even in pre-acceptance tests the notes point out that they loaded up to 2000# ballast in the nose to represent the accepted loading.
I suggest you look at the 4 X 20mm cannon installation in the Westland Whirlwind, this was very compact but had to us the 60 round drum magazines as belt feed was not an option at the time. The nose of the Whirlwind does not have nose gear eating up space but the frontal area is very small. With belt feed around 120 rounds per gun was considered possible I believe without major redesign
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There were definite plans for a version with four 20mm guns in a single horizontal row with at least 120 rounds per gun. If you look at the second picture above you can see the ammo drum for the port lower cannon and an empty space of at least the same volume above it in the void between the two armour plates. Some time a go on another forum (I have forgotten when and where) there was a suggestion that up to 2 rounds per gun could have been fitted with a custom built belt feed! So giving a P38 four cannons instead of the 0.5's might have been possible. When judging weight of fire and effectiveness I recommend Tony William's wed site where he uses multipliers to allow for the effectiveness of explosive rounds.
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There were definite plans for a version with four 20mm guns in a single horizontal row with at least 120 rounds per gun. If you look at the second picture above you can see the ammo drum for the port lower cannon and an empty space of at least the same volume above it in the void between the two armour plates. Some time a go on another forum (I have forgotten when and where) there was a suggestion that up to 2 rounds per gun could have been fitted with a custom built belt feed! So giving a P38 four cannons instead of the 0.5's might have been possible. When judging weight of fire and effectiveness I recommend Tony William's wed site where he uses multipliers to allow for the effectiveness of explosive rounds.
I suggest you look at the 4 X 20mm cannon installation in the Westland Whirlwind, this was very compact but had to us the 60 round drum magazines as belt feed was not an option at the time. The nose of the Whirlwind does not have nose gear eating up space but the frontal area is very small. With belt feed around 120 rounds per gun was considered possible I believe without major redesign
.
There were definite plans for a version with four 20mm guns in a single horizontal row with at least 120 rounds per gun. If you look at the second picture above you can see the ammo drum for the port lower cannon and an empty space of at least the same volume above it in the void between the two armour plates. Some time a go on another forum (I have forgotten when and where) there was a suggestion that up to 2 rounds per gun could have been fitted with a custom built belt feed! So giving a P38 four cannons instead of the 0.5's might have been possible. When judging weight of fire and effectiveness I recommend Tony William's wed site where he uses multipliers to allow for the effectiveness of explosive rounds.
Is the "empty space" where the gent is about to install the mag fpr the top gun that he is holding???
I suggest you look at the 4 X 20mm cannon installation in the Westland Whirlwind, this was very compact but had to us the 60 round drum magazines as belt feed was not an option at the time. The nose of the Whirlwind does not have nose gear eating up space but the frontal area is very small. With belt feed around 120 rounds per gun was considered possible I believe without major redesign
.
There were definite plans for a version with four 20mm guns in a single horizontal row with at least 120 rounds per gun. If you look at the second picture above you can see the ammo drum for the port lower cannon and an empty space of at least the same volume above it in the void between the two armour plates. Some time a go on another forum (I have forgotten when and where) there was a suggestion that up to 2 rounds per gun could have been fitted with a custom built belt feed! So giving a P38 four cannons instead of the 0.5's might have been possible. When judging weight of fire and effectiveness I recommend Tony William's wed site where he uses multipliers to allow for the effectiveness of explosive rounds.
But still, at the very best only 120 rounds per gun. 10 to 12 seconds of firing time. It doesn't seem like enough.
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I think I'd rather have 37.5sec of (moderately) heavy fire than (not quite) 14 heavy & (not quite) 24 lighter, even if the 20mm had zero chance of jamming.
I do appreciate the P-38 was complicated & Lockheed wasn't really well-prepared for (genuinely) mass-production. What I meant is, based on my understanding of the state of affairs in the company, things were pretty chaotic; were they so chaotic Lockheed was incapable of making a running change to the canopy? Was it so much worse, compared to NAA or Republic, that was impossible? Was demand for the P-38 so much higher than for P-51 or P-37? I'd have to say the answer to all of those was no; am I wrong?