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

[davebender]

David McCambell who left the Essex with 1/2 tank of fuel, shot down 9 Japanese planes

I believe some Me-109 pilots achieved more then 9 kills on a single day. Multiple sorties were required but David McCambell also had the option to land for more fuel and ammo.

 

[Lighthunmust]

I think both sides of the argument being made have very valid points. With the P-38 one thing to consider regarding the weight of extra .50 cal ammunition, which may or may not weigh more than the cannon and shell it would replace, is that it would be in the best possible place to not adversely effect maneuvering. Discarding the less reliable cannon would certainly simplify maintenance and the logistical requirements of supplying two types of ammunition and replacement parts. For the P-38 this may be the best choice because fuel in not much of an issue. Does anyone have reports of P-38s going on missions without functioning or armed cannons due to maintenance or logistics problems? I would not be surprised to learn this may have occasionally happened in the PTO.

 

[pinsog]

I believe some Me-109 pilots achieved more then 9 kills on a single day. Multiple sorties were required but David McCambell also had the option to land for more fuel and ammo.

Multiple sorties per day is not an option when you fly from England to Germany. When David McCampbell shot down 9 Japanese planes in 1 mission, he broke off contact with targets still available, he shot down no more aircraft that day. If he had more ammo, and a full tank of fuel when he left the ship, how many might he have gotten? Lets put McCampbell in a P38 flying from a nearby island helping defend the fleet, with a full tank of fuel. The P38 already carries 500 rounds per gun, 100 more per gun than the Hellcat. The guns are concentrated in the nose. Could he have knocked down more Japanese dive bombers? Lets make the total 600 rounds per gun, or 700 rounds per gun. What ever the weight of the cannon, its mount and ammo, I would have deleted that stuff and put that much more 50 ammo. That is how I would have armed the P38. IMHO against the aircraft it fought, losing the 20mm would have not been an issue.

Can anyone tell us how much the cannon, its mount, and the 20mm ammo weighed in a P38? That would let us know how much more 50 ammo we could carry with no performance penalty.

 

[Lighthunmust]

Multiple sorties per day is not an option when you fly from England to Germany. When David McCampbell shot down 9 Japanese planes in 1 mission, he broke off contact with targets still available, he shot down no more aircraft that day. If he had more ammo, and a full tank of fuel when he left the ship, how many might he have gotten? Lets put McCampbell in a P38 flying from a nearby island helping defend the fleet, with a full tank of fuel. The P38 already carries 500 rounds per gun, 100 more per gun than the Hellcat. The guns are concentrated in the nose. Could he have knocked down more Japanese dive bombers? Lets make the total 600 rounds per gun, or 700 rounds per gun. What ever the weight of the cannon, its mount and ammo, I would have deleted that stuff and put that much more 50 ammo. That is how I would have armed the P38. IMHO against the aircraft it fought, losing the 20mm would have not been an issue.

Can anyone tell us how much the cannon, its mount, and the 20mm ammo weighed in a P38? That would let us know how much more 50 ammo we could carry with no performance penalty.

From AHT by Dean page 145, tables 19 and 20.

For the P-38J
(1) 20mm cannon installed 196 lbs.
20mm ammunition 92 lbs. for all load plans

(4) Cal. .50 Installed 425 lbs.
.50 cal ammunition = normal load 249 lbs. or three alternate loads plans each having 622 lbs.

150 rounds of 20mm ammo weighs 92 lbs.
800 rounds of .50 ammo weighs 249 lbs., 2000 rounds weighs 622 lbs.


I have no idea how much extra rpg could be made to fit with removal of the cannon, but if space would not be a problem, easily 200 extra rpg. Please do the math if you want a precise number.

 

[tomo pauk]

By the US 100K book, the cannon installation weights 196lbs, with further 92lbs for 150 pcs of ammo (totaling 288; firing time 15sec), while one gun its ammo weighted 261lbs (500 pcs, firing time 33sec). Replacing a cannon with one HMG ammo yields reduction of firepower by 25% (my estimate) for 1st 15 seconds of firing, but increases it by 25% for 2nd 18 seconds. Perhaps 5 x .50cals, tightly grouped, are at least as good as wing mounted 6 x .50cals?

 

[Lighthunmust]

By the US 100K book, the cannon installation weights 196lbs, with further 92lbs for 150 pcs of ammo (totaling 288; firing time 15sec), while one gun its ammo weighted 261lbs (500 pcs, firing time 33sec). Replacing a cannon with one HMG ammo yields reduction of firepower by 25% (my estimate) for 1st 15 seconds of firing, but increases it by 25% for 2nd 18 seconds. Perhaps 5 x .50cals, tightly grouped, are at least as good as wing mounted 6 x .50cals?

I think 5 in the nose would be more effective than 6 in the wings regardless of rps because of concentration at all ranges, perhaps 4 would also be. This however requires being a good shot. How many times did the dispersion of 6 in the wing fired outside the point of convergence manage to catch an opponent with just enough to do the job. I personally have seen what one .50 bullet can do to a target and it was impressive.

 

[tomo pauk]

Perhaps 90% of fighter planes deployed in Eastern front have had hull weapons only, yet I've didn't read that those planes were in disadvantage re. hit probability. Another thing that can be considered is that Fw-190D-9 did have wing guns deleted (ditto for P-39 in VVS service), yet I have to read about complain considering reduced hit probability.

I think 5 in the nose would be more effective than 6 in the nose

6 in the wings

 

[Lighthunmust]

Perhaps 90% of fighter planes deployed in Eastern front have had hull weapons only, yet I've didn't read that those planes were in disadvantage re. hit probability. Another thing that can be considered is that Fw-190D-9 did have wing guns deleted (ditto for P-39 in VVS service), yet I have to read about complain considering reduced hit probability.


6 in the wings

Perhaps it would take someone with a fair amount of experience in both to make an accurate assessment. When I think of target sleeve shooting, I'm guessing making hits with 6 in the wing was easier. However, wouldn't the short distance from the cockpit to the nose make deflection shooting easier in a P-38? - Lighthunmust

Whoops! Senior moment. Fixed it. - Lighthunmust

 

[fastmongrel]

As I recall it was only because of the British that the F4F was "upgraded" to six guns.

I have have heard this repeated many time but never understood it. How can the Royal Navy FAA be blamed for lumbering the F4F-4 with 6 guns. The customer for Grumman was the US government and the RN got what it was given under lend lease. Why would Grumman upset the people who were paying its bills to build an aircraft for a customer who had less than zero say in the design and production. I can imagine the RN asking for 6 guns but why would the US government who controlled the contracts listen to them they never did on any other lend lease weapon. If the British wanted something different they had to pay for it and or do the work themselves. A good example is the fuel stowage on escort carriers which wasnt up to RN standards as built, the RN had to have them modified after delivery from the shipyard.

 

[Lighthunmust]

I have have heard this repeated many time but never understood it. How can the Royal Navy FAA be blamed for lumbering the F4F-4 with 6 guns. The customer for Grumman was the US government and the RN got what it was given under lend lease. Why would Grumman upset the people who were paying its bills to build an aircraft for a customer who had less than zero say in the design and production. I can imagine the RN asking for 6 guns but why would the US government who controlled the contracts listen to them they never did on any other lend lease weapon. If the British wanted something different they had to pay for it and or do the work themselves. A good example is the fuel stowage on escort carriers which wasnt up to RN standards as built, the RN had to have them modified after delivery from the shipyard.

Perhaps because the American decision makers where echelons above reality in comparison to the complaining pilots who were not given a chance to provide imput. Grumman may have seen the handwriting on the wall regarding future fighter armament, or just didn't care one way or the other because nobody in the USN leadership objected. I don't know. I'll check my books.

 

[Lighthunmust]

I have have heard this repeated many time but never understood it. How can the Royal Navy FAA be blamed for lumbering the F4F-4 with 6 guns. The customer for Grumman was the US government and the RN got what it was given under lend lease. Why would Grumman upset the people who were paying its bills to build an aircraft for a customer who had less than zero say in the design and production. I can imagine the RN asking for 6 guns but why would the US government who controlled the contracts listen to them they never did on any other lend lease weapon. If the British wanted something different they had to pay for it and or do the work themselves. A good example is the fuel stowage on escort carriers which wasnt up to RN standards as built, the RN had to have them modified after delivery from the shipyard.

I have found a secondary sources without specific documentation of this information, just a list of sources. I checked Tillman's "Wildcat" and all I found was that at one time there were two separate production lines at Grumman for F4Fs and Martlets. According to Dean in AHT page 494 Gun Platform and Weapon Performance there were many complaints from USN aviators such as "The reduction of rounds per gun cut the firing time by at least five seconds. That doesn't seem like much, but can be a lifetime in combat". Dean writes "The FM-1 and the FM-2 versions by Eastern went back to four guns with more ammunition per gun. THE BRITISH, WHO INSTIGATED THE SIX GUN ARRANGEMENT THE -4 VERSION USED FOR COMMONALITY OF MANUFACTURE, STAYED WITH THIS CONFIGURATION." (capitalization added for emphasis) Dean is a respected source. I think Grumman, who would soon stop making Wildcats to concentrate on Hellcats, decided to make a production decision to reduce the costs of running two production lines and the USN Brass did not care.

 

[Lighthunmust]

Do we ditch the cannon for more .50cal ammo and/or an extra M2 or two?

 

[Shortround6]

Do we ditch the cannon for more .50cal ammo and/or an extra M2 or two?

Ditching the cannon for more ammo seems rather pointless. You are trading 40% of your striking power in the first 15 seconds for extended firing time for the American fighter that carried more rounds per gun for it's .50s than any other. If the P-38 is carrying 500rpg it has another 5 seconds of firing time over a P-47 carrying 425 rpg and 7 seconds more firing time than the Navy fighters. It has 2 1/2 times the firing time of some P-40s.

Swapping the 20mm and it's 150 rounds of ammo for a 5th M2 with 500rounds saves about 64lbs. you are giving up about 28% of your firepower in the first 15 seconds for 25% more firepower in seconds 16-33 compared to a normal P-38.

This makes more sense than the first option.

Trying to add a 6th M2 is self defeating. If you keep all six guns at 500rpg you will have increased the armament weight by about 286lbs. If you have room for the ammo. 1000 rounds of .50 cal ammo takes up how much volume compared to 150 rounds of 20mm?
Less ammo for all six guns or 4 guns keep 500rpg and two guns run out a lot sooner?
That 286lb is over 900 rounds of .50 cal ammo. How do you want to divvy it up?

 

[pinsog]

I seriously dont think you need a 20mm cannon to shoot down a Zero or a 109 or for that matter even a 190. 4 Bronwing 50,s that close together will annialate anything short of anAmerican medium bomber. Using a 20mm on any of those 3 planes is like using buckshot on a dove

 

[Shortround6]

I seriously dont think you need a 20mm cannon to shoot down a Zero or a 109 or for that matter even a 190. 4 Bronwing 50,s that close together will annialate anything short of anAmerican medium bomber. Using a 20mm on any of those 3 planes is like using buckshot on a dove

Dove's don't shoot back

 

[pinsog]

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

 

[Shortround6]

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

I believe you have said that already.

Now, could you have GUARANTEED in 1942 or 1943 that those 3 aircraft are the ONLY aircraft the P-38 would have to shoot down?
No Me 110s, no Me 210/410s, no Ju-88s, No Do 217s. No Japanese Sally's, or Betty's. How about an Emily or two?

And if I had to do a head on pass at at a Fw 190 that had four 20mm cannon I would want all the firepower I could get in my plane.

 

[pinsog]

I didnt realize I double posted. So much for multi tasking. If I were in a single engine fighter I would want 6 50's or something. The sole reason I think the Lightning could get away with 4 is because they are all concentrated. I guess to each his own. We'll just have to disagree. I'd want more firing time and you'd want more hitting power. I think we can all agree it's a good thing the Germans didn't have it. The P38-K with German cannon would have been a devistating bomber destroyer. So would a cannon armed P47.

 

[Lighthunmust]

Ditching the cannon for more ammo seems rather pointless. You are trading 40% of your striking power in the first 15 seconds for extended firing time for the American fighter that carried more rounds per gun for it's .50s than any other. If the P-38 is carrying 500rpg it has another 5 seconds of firing time over a P-47 carrying 425 rpg and 7 seconds more firing time than the Navy fighters. It has 2 1/2 times the firing time of some P-40s.

Swapping the 20mm and it's 150 rounds of ammo for a 5th M2 with 500rounds saves about 64lbs. you are giving up about 28% of your firepower in the first 15 seconds for 25% more firepower in seconds 16-33 compared to a normal P-38.

This makes more sense than the first option.

Trying to add a 6th M2 is self defeating. If you keep all six guns at 500rpg you will have increased the armament weight by about 286lbs. If you have room for the ammo. 1000 rounds of .50 cal ammo takes up how much volume compared to 150 rounds of 20mm?
Less ammo for all six guns or 4 guns keep 500rpg and two guns run out a lot sooner?
That 286lb is over 900 rounds of .50 cal ammo. How do you want to divvy it up?

What you write makes perfect sense. It also may not make perfect sense it you consider the logistical support necessary for the 20mm, known reliability issues, lower rate of fire, frequent target rich environment of easy to disable opponents at the beginning of P-38 service, and poor marksmanship of almost all pilots. Fighter pilots miss more often than hit, as Bong's experience demonstrates.

This question cannot be definitively answered with the data so far presented in this thread. The trend of the majority opinion appears to be ditch the cannon. My experience is that Majorities are frequently disastrously wrong. I am going back to Bodie's book to look for better data.

 

[pinsog]

I believe you have said that already.

Now, could you have GUARANTEED in 1942 or 1943 that those 3 aircraft are the ONLY aircraft the P-38 would have to shoot down?
No Me 110s, no Me 210/410s, no Ju-88s, No Do 217s. No Japanese Sally's, or Betty's. How about an Emily or two

And if I had to do a head on pass at at a Fw 190 that had four 20mm cannon I would want all the firepower I could get in my plane.

FM2 Wildcats handled Sally's, Betty's, and Emily's just fine, and it's 4 50's weren't concentrated like a P38.

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

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.

We just think different. I'd rather have more firing time and you'd rather have more hitting power. 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.