How would you have armed the P38 if you were to use it as it was used historically?

[NZTyphoon]

I dont really think you need a 20mm cannon to shoot down a Zero, ME109 or even a FW190. Using a 20mm on anyone of them is like using buckshot on a dove

In air-to-air combat the idea is to shoot down an aircraft in as little a time as possible, because the more time a fighter pilot had to concentrate on one target meant there was more time for an opponent to get in some shooting of their own. Most combat during WW2 involved a few seconds of firing time, if that - ideally a diving pass from behind - there simply wasn't the time to line up and squeeze off a precision shot as in deer hunting. If a 20mm cannon could do the job more quickly and efficiently than .50s alone it didn't matter if there was some "overkill". As someone famous once quipped (and I wish I could remember who) "You don't need a sledgehammer to crack a nut, but if you want to destroy the nut use the sledgehammer."

Yep, FM2s and Mustangs could handle the job, but then the P-47 with 8 .50s and P-61s with four .50s and four 20mm cannon shot down aircraft most efficiently, as well as being highly effective at ground attack.

 

[Lighthunmust]

In air-to-air combat the idea is to shoot down an aircraft in as little a time as possible, because the more time a fighter pilot had to concentrate on one target meant there was more time for an opponent to get in some shooting of their own. Most combat during WW2 involved a few seconds of firing time, if that - ideally a diving pass from behind - there simply wasn't the time to line up and squeeze off a precision shot as in deer hunting. If a 20mm cannon could do the job more quickly and efficiently than .50s alone it didn't matter if there was some "overkill". As someone famous once quipped (and I wish I could remember who) "You don't need a sledgehammer to crack a nut, but if you want to destroy the nut use the sledgehammer."

Yep, FM2s and Mustangs could handle the job, but then the P-47 with 8 .50s and P-61s with four .50s and four 20mm cannon shot down aircraft most efficiently, as well as being highly effective at ground attack.

All you write is true. However, the options with the P-38 prevent the use of four 20mm cannon and probably more than five .50s. I also think many agree the concentration of fire in the nose in most cases make an accurate 2-3 second burst of five .50s as effective in reality as the 4 MG +1 AC. You only need to sufficiently crack the nut, the ground will destroy the nut, and your logistics will be easier. Fighter pilots miss more often than hit. Fighter pilots are more often targets than shooters. "Good generals study tactics, great generals study logistics".

 

[Shortround6]

Early P51's handled all those German aircraft also, and again, it's 4 50's weren't concentrated like a P38.

then why did they go to six guns? ground strafing?

I would also avoid head on passes on any bomber destroyers no matter what my plane was armed with if at all possible, but with 4 flatter shooting 50's concentrated in the nose, you should be getting hits on him before he gets hits on you, and with no dispersal of your rounds like on a single engine fighter.

You don't always have a choice, This flatter shooting advantage of the .50 may be a lot of hoopla with little to back it up. Yes the .50 shoots flatter as can be proved by any number of trajectory tables. But at any practical air to air range in WW II the difference of even a couple of feet of trajectory doesn't make a lot of difference. Very few pilots were trying 1000yd shots and against all but the smallest fighters the target is 5-6 feet high or larger. Your .50 gets him right smack dab in the middle and his not so flat shooting 20mm blows the bottom out of your fuselage, what was the practical difference again?
Shorter time of flight is more of an advantage.
In a head on pass with 400mph aircraft your are closing on each other and around 400yds per second. Time on target is going to be very brief, and it doesn't matter if you puncture every fuel tank he has, wreck his oil cooler, hole a hydraulic line and the oil tank and even knock a cylinder of his radial, he is a goner for sure, but none of the damage will take effect before his shells hit you. A single 20mm won't blow him out of the sky but the more damage you can do in a shorter amount of the time the more successful you will be.

Just like deer hunting, I've seen everything in deer camp from .223 up through .375 and everyone swore their gun was the best deer rifle.

Just like the doves, the deer aren't shooting back.

Somebody once said about African hunting ( close to this) "when you are standing 50yds away from an angry elephant, anything you can hold in your hands seems too small"

If four .50s worked so well Against the Japanese planes why was the Navy trying to mount a pair of 20mm guns in the F6F for two 20mm and four .50s and why were they trying to mount four 20mm in the Corsair? Not to mention shifting to the 20mm guns for practically every fighter except the very first F8Fs and FH Phantoms? They didn't believe their own combat results?

 

[Shortround6]

All you write is true. However, the options with the P-38 prevent the use of four 20mm cannon and probably more than five .50s. I also think many agree the concentration of fire in the nose in most cases make an accurate 2-3 second burst of five .50s as effective in reality as the 4 MG +1 AC. You only need to sufficiently crack the nut, the ground will destroy the nut, and your logistics will be easier. Fighter pilots miss more often than hit. Fighter pilots are more often targets than shooters. "Good generals study tactics, great generals study logistics".

Once again, the "nut" isn't shooting back. How long can a liquid cooled engine last with a holed radiator? Or any engine last with a holed oil tank or shot away oil line. The plane may not make it's home field and the ground will destroy the "nut" but will the nut get in a burst or two at a wingman or squadron mate?
How many enemy planes were claimed as "damaged" compared to how many shot down?
What percentage of P-38 pilots, with out having gone strafing, landed with empty guns? What percentage even used all the cannon ammo, assuming the gun didn't jam?
Knowing the ACTUAL need for more ammo rather than a PERCEIVED need for more ammo would go a long way in answering this question.

 

[pinsog]

Shortround6,

"If four .50s worked so well Against the Japanese planes why was the Navy trying to mount a pair of 20mm guns in the F6F for two 20mm and four .50s and why were they trying to mount four 20mm in the Corsair? Not to mention shifting to the 20mm guns for practically every fighter except the very first F8Fs and FH Phantoms? They didn't believe their own combat results?"

None of these aircraft had guns concentrated on the centerline like the P38 either. Was it Gunther Rall that said something like 2 guns on the centerline was worth 4 in the wings? Someone help me with that quote please.

I'm definately not saying your wrong, I could actually argue your side of the argument and I'm sure you could argue mine to, the only reason I'm saying we could ditch the cannon is how fragile the opponents it was facing was, Zero's and ME109's were particularly fragile. If I was in a P38 having to fight P47's, I'd keep the cannon! But, also I have been reading war stories for just over 30 years now ALOT of times the pilots were quoted as saying they were out of ammo and ran for home.

You said doves, deer and nuts don't shoot back, neither do Zero's, 109's and 190's.....................as long as your behind them.;o)

 

[Lighthunmust]

Once again, the "nut" isn't shooting back. How long can a liquid cooled engine last with a holed radiator? Or any engine last with a holed oil tank or shot away oil line. The plane may not make it's home field and the ground will destroy the "nut" but will the nut get in a burst or two at a wingman or squadron mate?
How many enemy planes were claimed as "damaged" compared to how many shot down?
What percentage of P-38 pilots, with out having gone strafing, landed with empty guns? What percentage even used all the cannon ammo, assuming the gun didn't jam?
Knowing the ACTUAL need for more ammo rather than a PERCEIVED need for more ammo would go a long way in answering this question.

That is certainly a great question. I wonder how hard it will be to find the data to answer it. If a "nut" isn't cracked enough to prevent it from shooting back, it ain't cracked. Four .50s cracked alota of "nuts". If you are making solid hits with five nose mounted .50s the end result will not be much different from 4+1, maybe not a messy in the air but just as messy when everything hits the ground. I am surprised the subject of Howard and the situation resulting in his Medal of Honor hasn't been mentioned. Four was enough until he ran out of ammunition but not guile and courage. We already have ample examples of USN aviators thinking four was enough until they ran out of ammunition.

 

[Njaco]

How many .50 bullets did it take to bring down...say, a 109?
How many 20mm shells?

Whats the weight of 4 fully loaded .50s and 2 fully loaded 20mm?

I would think that if it takes one or two shots from a 20mm to take out an opponent that leaves more ammo to get more compared to the .50s.

 

[pinsog]

How many .50 bullets did it take to bring down...say, a 109?
How many 20mm shells?

Whats the weight of 4 fully loaded .50s and 2 fully loaded 20mm?

I would think that if it takes one or two shots from a 20mm to take out an opponent that leaves more ammo to get more compared to the .50s.

It is a legitimate point IF you could connect with every round. But if you could connect with every round I would put the 37mm out of the P39 in it with 100 rounds and shoot down everything in the air. You have alot more ammo to miss with carrying 50's than you do when carrying 20mm. Again,like shooting doves with buckshot, sure buckshot will kill a dove, but you gotta hit it first. It takes more #8 birdshot, but you alot more likely to hit it to.

 

[Lighthunmust]

I stopped being lazy. I broke out Dean and Bodie.

From Dean's "America's Hundred-Thousand" pages 133, 134, 135 -

Cyclic rate of the 20mm is 600 rpm
Cyclic rate of the .50 BMG is 800-900 rpm

Even if the cyclic rates given are a little high, the cannon is almost certainly 30% slower than the .50 BMG. This means that there is more of a gap in all directions of flight between fired cannon ammunition and consequencly a greater chance for a miss. - Lighthunmust

Firing time of the P-38s 20mm is 15secs
Firing time of the P-38s .50s it is 33.3 seconds.

This means that only the four .50s were available for more than half the firing. Considering how many times I have read of pilots missing with their first bursts, the .50s were probably accounting for most of the killing. - Lighthunmust

Total projectile throw weight per second for P-38 with 4+1 = 9.26 lbs
Total projectile throw weight per second for P-40E with 6x.50=9.54 lbs

Granted that cannon shells explode at all ranges. The shortness of engagement ranges somewhat negates this advantage especially when considering the limited number of hits possible per second. More rounds per minute and for more bursts would be available for aircraft known to be easy (includes most WW2 aircraft) to destroy - Lighthunmust

From Bodie's "The P-38 Lightning" -

The following is a summary of two paragraphs from p.82 and a caption from p.87:

In March 1942 three different P-38 nose configurations of four 20mm were tried. Throw weight per second increased 50% but with a reduction of firing time to 5.13 seconds. Normal armament (4+1) of P-38F is 40 seconds. (note this conflicts with Dean but Dean did not give a model letter designation)

They also tested a proposed nose of four .50s and two 20mms that increased throw weight per second by 35% but this was using a P-38 as a test bed for the XP-49. Page 87 has a photograph of this arrangement. The photo's caption also mentions the fitting of eight 50s and another fitting of three .60s. There is no mention of actual loading of ammunition and firing from the P-38, but the larger XP-49 would have 500 rpg of .50 and 90 rpg of 20mm.

End of summary of Bodie paragraphs.

The .60 caliber was a 20mm cartridge necked down to .60 caliber, which was a dumb idea. This arrangement indicates that three 20mm with sufficient ammunition may have been possible. There is no text indicating if six, let alone eight .50s could have been supplied with sufficient ammunition for a firing time equal to a fighter with six or eight wing guns. I think it is doubtful they could. I still think all things considered that four .50s (with a longer firing time) or five .50s (7.95 throw weight per second) for the P-38 would when all things are considered be effectively equal to the 4 +1 in destroying aircraft. It would have reduced logistical requirements and ultimately been a more efficient weapons package for the P-38. For whatever reason they stuck to the 4+1 even when having the possible heavier throw weight of four 20mms or six .50s. I'll bet firing time was a factor in this decision, not just change of production issues. - Lighthunmust

P.S. Fighter pilots miss more often than hit. Fighter pilots are more often targets than shooters.

 

[Shortround6]

the US navy figured that one 20mm gun was worth three .50 calibers in effectiveness. The throw weight works just fine if you are firing solid (non-exploding) projectiles. Relative effectiveness changed back and forth a bit as the war went one because ammo did not stay the same. Neither the 20mm Hispano or the .50 cal in aircraft use finished the war using the same ammo they started with. Effectiveness in combat reports will vary from year to year depending on ammo. The US didn't get really good .50cal ammo (the M8 API) until 1943 and it wasn't the predominate round until sometime in 1944.

The Germans figured fighter pilots hit, on average, with about 2% of their rounds fired. I repeat, ON AVERAGE. This includes super aces, who do much better, and green pilots, who do much worse. The bigger guns ammo is much more destructive on a weight for weight basis, which is why the Germans shifted to the 30mm guns. It was almost impossible for a single engined fighter to carry enough 20mm ammo to "average" one kill per flight against 4 engined bombers. It was possible using 30mm ammo.
It is the same principle with the.50 cal vs 20mm.
The 20mm round may be 4 times as effective as the .50 cal round. the 3 times as effective for the gun's rating takes into account the rates of fire between the guns. The 20mm ammo is only a bit over double the weight of the .50cal ammo.
3-5 hits from a 20mm gun may be enough (on average) to bring down a single engine fighter. How many hits does the .50 need, on average?

By the way. the .60 caliber was an attempt at higher muzzle velocity. Studies and calculations had shown the US Army that increasing the velocity would greatly increase the chances of hitting. This a good idea on the face, the "dumb" part is that such ultra high velocity guns are heavy and require heavy ammunition. They also suffer from extreme barrel wear.

 

[pinsog]

Shortround6,
"3-5 hits from a 20mm gun may be enough (on average) to bring down a single engine fighter. How many hits does the .50 need, on average"

Depends on where you hit them. Everyone speaks of how much more damage a 20mm does than a 50, but would someone please point out a safe place on a single engine fighter like the Zero, ME109 or FW190 that could absorb a 2 second burst from 4 concentrated 50's? If you hit a Zero, ME109 or FW 190 anywhere between the prop hub, 2 feet behind the pilot and between the swastikas on the wings with a solid burst from 4 concentrated 50's in the nose of a P38, i would think it is a done deal. Your either gonna kill the engine, pilot, tear off a wing, flame a fuel tank, blow up ammo in the wing, or cause some sort of massive structural failure.

 

[P-40K-5]

2 seconds of accurate fire will bring down almost any fighter. the trick is trying to get that accurate burst.

Erich Hartmann a few others mastered that trick.

anyways, a few hits from a 109 cannon was enough to bring down a fighter. that means less time shooting
at the e/a, which means more time to engage the next target, watch your back, or get the hell out of there.

 

[Lighthunmust]

the US navy figured that one 20mm gun was worth three .50 calibers in effectiveness. The throw weight works just fine if you are firing solid (non-exploding) projectiles. Relative effectiveness changed back and forth a bit as the war went one because ammo did not stay the same. Neither the 20mm Hispano or the .50 cal in aircraft use finished the war using the same ammo they started with. Effectiveness in combat reports will vary from year to year depending on ammo. The US didn't get really good .50cal ammo (the M8 API) until 1943 and it wasn't the predominate round until sometime in 1944.

The Germans figured fighter pilots hit, on average, with about 2% of their rounds fired. I repeat, ON AVERAGE. This includes super aces, who do much better, and green pilots, who do much worse. The bigger guns ammo is much more destructive on a weight for weight basis, which is why the Germans shifted to the 30mm guns. It was almost impossible for a single engined fighter to carry enough 20mm ammo to "average" one kill per flight against 4 engined bombers. It was possible using 30mm ammo.
It is the same principle with the.50 cal vs 20mm.
The 20mm round may be 4 times as effective as the .50 cal round. the 3 times as effective for the gun's rating takes into account the rates of fire between the guns. The 20mm ammo is only a bit over double the weight of the .50cal ammo.
3-5 hits from a 20mm gun may be enough (on average) to bring down a single engine fighter. How many hits does the .50 need, on average?

By the way. the .60 caliber was an attempt at higher muzzle velocity. Studies and calculations had shown the US Army that increasing the velocity would greatly increase the chances of hitting. This a good idea on the face, the "dumb" part is that such ultra high velocity guns are heavy and require heavy ammunition. They also suffer from extreme barrel wear.

The USN experience with and rationale for 20mm is primarily based on ship-borne AA defense gunners. These gunners would be expected to open fire at distances much greater the typical 200 yards of effective air to air accuracy. They could do this effectively because their ammunition did not rely on kinetic energy.

The German data is primarily based on the need to shoot down U.S. Heavy Bombers. They came to the conclusion that just having the cannon was not enough because they could not carry enough 20mm or 30mm in their 109s and 190s. Hence the effort to design single engine aircraft with more ammunition capacity or/and bigger cannon. They never went down the other path of more HMG and ammunition and that may be because the 109 and 190 could not efficiently do this. The Germans were also looking at the issue with regard to standoff range for twin-engined bomber destroyers staying out of the range of American .50s.

It can take only one hit from a .50 to kill or incapacitate the pilot or engine. Erich Hartmann's "Stick your nose in his cockpit" is not so much a trick to master as having the resolve to close with the enemy because of limited ammunition for taking low hit probability shots at greater distances. Robert Johnson's P-47 was hit with multiple 20mm shells. The last 190 to attack him was out of cannon shells and ineffective. Just a change to one cowl mounted 12.7mm for the two 7.92s would have probably end Johnson's career.

The USAAF could have retained 20mms in the Mustang and put them in the Thunderbolt. They didn't. They also started out with .50s in the F-80, F-84, and F86. Only the ineffectiveness due to insufficient oxygen at Korean War altitudes, better fire controls, increased aircraft size, and better quality cannons forced a change.

The .60 was a dumb idea for the reasons you stated and other reasons. As you yourself have said in other words elsewhere, "flat shooting" trajectories were over-rated for the ranges of engagement. I have as many books on firearms as aircraft. Have reloaded ammunition for accuracy, shot competition, and have experience with automatic weapons domestic and foreign up to a four 12.7mm Dshk mounted antiaircraft system. What I don't have is the loose government money available in WW2 to be thrown at every poorly conceived (dumb) idea. The .60 was like the .220 Swift in a world where the more efficient .22-250 and .243 prevail.

Getting back to the main point: for the P-38, disregarding other fighters, the cannon may have not been the best answer.

 

[P-40K-5]

yep Erich's sticking his nose into the cockpit got him the highest kills in aviation history.. that nobody will
ever touch. nice trick indeed.

 

[Lighthunmust]

yep Erich's sticking his nose into the cockpit got him the highest kills in aviation history.. that nobody will
ever touch. nice trick indeed.

A "trick" others on both sides were aware of. A target rich environment of lessor opponents and lack of pilot rotation is the biggest reason for the kill count.

 

[P-40K-5]

A "trick" others on both sides were aware of. A target rich environment of lessor opponents and lack of pilot rotation is the biggest reason for the kill count.

two fold.. he never lost a wingman.. nutter nice trick. he also let his wingman fly his personal a/c.. etc.,etc.,etc.
target rich enviroment means that theres that many more e/a hunting for him too.. so that arguement dosn't
fly in my book. he also refused to fly any other a/c.

 

[Jabberwocky]

I stopped being lazy. I broke out Dean and Bodie.

The .60 caliber was a 20mm cartridge necked down to .60 caliber, which was a dumb idea. This arrangement indicates that three 20mm with sufficient ammunition may have been possible.

Just a small correction.

There were two wartime .60 cal experimental aircraft guns in the US.

One, the T18, was based on the Hispano, but it considered too much work to get it right. It was dropped pretty early on - 1942 I think

The other was loosely based on the German MG151/15 (15 x 96 mm). This was necked out to accept the US experimental 15.2 x 114 anti-tank cartridge and went through several iterations.

It was never really successful. RoF and M/V were good, but the weapon was considered too heavy and not reliable enough. Despite an order for 3000 guns, only 300 were made and it and was dropped after about 10 years of messing about with various experimental designs.

 

[Lighthunmust]

Just a small correction.

There were two wartime .60 cal experimental aircraft guns in the US.

One, the T18, was based on the Hispano, but it considered too much work to get it right. It was dropped pretty early on - 1942 I think

The other was loosely based on the German MG151/15 (15 x 96 mm). This was necked out to accept the US experimental 15.2 x 114 anti-tank cartridge and went through several iterations.

It was never really successful. RoF and M/V were good, but the weapon was considered too heavy and not reliable enough. Despite an order for 3000 guns, only 300 were made and it and was dropped after about 10 years of messing about with various experimental designs.

You are absolutely correct! It has been a while since I looked at "Flying Guns, World War II" by Williams and Gustin. I forgot about the MG151 based T17. The main point I am trying to make is for the technology of the day, you reached a point of diminishing satisfactory returns past the .50 until you reached 20mm. Since the 1980s there have been .50 projectiles that approach the terminal ballistics of WW2 era 20mm cannon shells. Everyone (especially Americans) should take a look at "Flying Guns". Americans will discover they do not have a monopoly on the world's greatest geniuses for gun and projectile design.

P.S. While "Flying Guns" does discuss and has tables of comparative cartridge destructiveness, and gun power and efficiency; I do not recall a comparative discussion or table of actual ffectiveness of the aircraft carrying these guns that includes ammunition firing times available. I will look more closely for this.

P.P.S. I found no discussion or tables of actual effectiveness of aircraft in regard to ammunition firing times. Except for the ineffectiveness of firing great quantities of rifle caliber ammunition. I did find comment about both sides during the war believing they had gun effectiveness problems.

 

[gjs238]

Any stats on actual P-38 cannon vs. MG usage and results?
Anecdotal from P-38 pilots?

 

[Lighthunmust]

Any stats on actual P-38 cannon vs. MG usage and results?
Anecdotal from P-38 pilots?

I'll take a look in my library when I can. It may take awhile as I am researching two other topics.