WI: NACA Modified P-38

[EverKing]

Ergonomics for fighter plane pilots. I think in those days it was just starting to be understood that flying fighters was different from flying bombers and transport planes. Not the least difference being only a single crew member. Who needed to keep his eyes out of the cockpit and on the surroundings as much as possible. And the grouping of the flight instruments, engine controls, gauges and fuel management controls and gauges should be placed for pilot efficiency not as an after thought during manufacture. Simplify and reduce the pilot workload so he concentrate more on looking out for the bogies.

It was a complaint leveled against the P-38 early in its career. See the "Final Report on the Tactical Suitability of the P-38F Type Airplane (6 March 1943)" Specifically, the conclusions which includes,

f. The cockpit installations are crowded and not arranged in a specific orderly fashion.

This was the impetus behind my re-arrangement of the cockpit (it goes beyond the Main Switch Box, mentioned above) ITTL P-38H and later. The Recommendations section also has many of the points that led directly to the modification of the starter system and switch arrangement (such as an automatic primer and ability to start both engines at once). These points were included in Narrative in Ch.13 Tuning and Tactical Report on the P-38F.

 

[Draconis]

The actual TL here is pretty limited in scope, as mentioned, and is solely based on the premise of adoption of the NACA recommendations before the US entry into the war. ITTL the decision and subsequent base-line improvement has led to other butterflies of improvements in the P-38 because of broader acceptance of its capabilities and therefore more willingness to devote resources to its improvement. Still, the final changes as they are currently have been small and incremental without major airframe redesigns--to the point where the early NACA P-38's even kept the same engine nacelles from the P-38E even though the (ATL) P-38F didn't need the oil radiators in the "chin." They kept a less favorable design because it was expedient and nothing more but they also soon realized that extra space could be used for core-type intercoolers, hurrying their adoption without needed to produce the large "chin" of the OTL P-38J/L (Model 422). The full list of TL To-Date alterations from the POD on to the current date of the Narrative (c. NOV-1944) can be found Here, many of which were historical additions/improvements anyway.

"Airframe/Systems Problems

• Limited dive speed due to Compressibility effect
  • Implement NACA recommended .2c chord extension on center wing [P-38F-1-LO Spring ‘42]
  • Move coolant and oil radiator to center wing LE for improved balance and aerodynamics [P-38F-1-LO Spring ‘42]
  • Extend Gondola trailing edge by 3 feet [P-38F-1-LO Spring ‘42]
  • Redesign canopy to increase its Critical Mach number [P-38F-1-LO Spring ‘42]
  • Install electric Dive Recovery Flaps [P-38H-20 (modified), P-38J/K (factory) Spring '44]
• Poor pilot visibility and egress due to the design of the five piece greenhouse canopy
  • Install a three part sliding canopy [P-38F-1-LO Spring ‘42]
  • Install a two piece sliding Bubble canopy [P-38J/K Spring ‘44]
• Insufficient charge cooling due to intercooler design
  • Install chin mounted core-type intercoolers [P-38F-1-LO Spring ‘42]
• Forward windshield does not allow installation of large gunsights
  • Redesign windshield to increase available space [P-38F-1-LO Spring ‘42]
  • Removal of separate Armored Glass, integration into forward windscreen [P-38F-1-LO Spring '42]
  • Further improvement with late models [P-38J/K Spring ‘44]
  • More to come
• Extra Internal Fuel
  • 55 US Gal. LE Tanks [P-38G Summer ‘42]
  • Reduced to 45 US Gal. LE Tanks [P-38J/K Spring '44]
• Cockpit Heat/Ventilation
  • Heat Exchanger off of Coolant Radiators (as P-39) [P-38H-1-LO Spring ‘43]
• Fuel Management
  • Install Electric Tank Selector system [P-38H-10-LO Summer ‘43]
  • Better fuel level indication/warning [P-38H-10-LO Summer ‘43]
• Electric Fuses cannot be replaced in flight
  • Replace fuses with pilot-accessible breaker box [P-38H-5-LO Spring ‘43]
• Engine Controls are complicated to adjust in emergencies
  • New unified engine control unit (power, rpm, props, and mixture) [P-38J/K Summer ‘44]
• Engine starters are difficult to use and only allow single engine starts
  • Replace manual fuel primer pump with automated electric primer [P-38H-10-LO Summer ‘43]
  • Unify the Energize/Mesh switches so there is one per engine [P-38H-10-LO Summer ‘43]
• Yoke limits cockpit space and blocks view of some instruments/main switch panel
  • Install single control stick [P-38J/K Spring '44]
• Turbo’s are prone to overspeed and failure
  • Automatic turbo rpm governor [P-38G-15 Late ‘42]
• Slow Initial Roll Rate, heavy control surfaces
  • Install Hydraulically boosted ailerons [P-38H-20 (Modification), P-38H-25 (factory) Winter/Spring ‘44]
• Carburetor Air Temperature Regulation
  • Pressure switch on vacuum line for CAT gauge which opens/closes shutters automatically [P-38H-1-LO Spring ‘43]
  • Add forward shutter with a second switch to close at lower CAT temps [P-38H-18-LO Late ‘43]
• Automatic Oil Temp Regulation
  • Pressure switch on vacuum line for Oil Temp Gauge with opens/closes shutters automatically [P-38H-1-LO Spring ‘43]
• Automatic Coolant Temp Regulation
  • Pressure switch on vacuum line for Coolant Temp Gauge with opens/closes shutters automatically [P-38H-1-LO Spring ‘43]
• Maneuver Flaps
  • 8 degree down, maneuver setting [P-38F-5-LO Late Spring ‘42]
• Propeller Efficiency
  • 4-Blade High-Activity Curtis Electric [P-38J Summer ‘44]
  • 4-Blade High-Activity Aeroprop [P-38K Late Spring '44]
• Single Generator
  • Add second generator on RH engine. [P-38G-1-LO Late Summer ‘42]
• Battery Heat
  • Move battery to rear compartment near the radios [P-38H-20 Jan ‘44]
• Limited Manifold Absolute Pressure
  • Water-Alcohol Injection [P-38J/K Summer ‘44]
    • Tanks ahead of main spar of inboard outer wing panel
• Limited External Store Load
  • Up-rated under-wing pylons for 300 gal tanks / 2000# bombs [P38G-5-LO Fall ‘42]
  • Outer wing mounts for 260# each [P38H-25 Spring '44]
  • More to come
• Weight Savings
  • Simplified Canopy [P-38J/K Spring '44]
  • Reduction of Turbo armor [P-38J/K Spring '44]
  • Slightly Reduced structure in booms (no longer needed after removal of the rads and battery) [P-38J/K Spring '44]

Production Problems

• Overall volume of Production
  • Vultee (VN): Ordered Spring ’43 after Consolidated Merger (Convair). In tooling up, it is determined they wouldn’t be able to meet demand, so they are first given Swordfish to develop two-seat TP-38’s [Beginning Production Autumn '43]
  • Bell (BE): Give up P-63 [Beginning P-38 Production Autumn '43]
    • P-39N Order 42-19241/19445 (205) kept in place
    • P-39Q-10-BE Order 42-21251/22245 (995) kept in place
    • P-63 Order: 42-68861/70860 (2000) re-allocated to P-39
    • P-63 Order: 43-10893/12092 (1200) re-allocated to P-38
    • P-63 Order: 44-4001/5100 (1100) re-allocated to P-38 (if needed)
• Production of alternate models
  • TP-38 [TP-38H-10-VN Autumn '43]
  • P-38(NF)
    • Single-Seat w/ AN/APS-6 [modified P-38H as P-38L Winter '43/'44]
    • Two-Seat w/ SCR-720A [modified TP-38H as P-38M Late Summer '44]
    • Single-Seat w/ AN/APS-6 [modified P-38J as P-38N Autumn '44]
    • More to come
• Production of Allison Engines
  • Cancellation of P-63 permits increased capacity for P-38 [Summer '43]

Doctrinal/Training Problems

• Lack of suitable training aircraft
  • Proper two-seat, dual control variant [TP-38H-10-VN Autumn '43]
• Proper Engine Out Training
  • Single engine practice / confidence building as standard training [Autumn '43]
  • Proper Engine Loss on Take-Off procedures [Developed Autumn '43, added to P-38 RTUs Winter '43/'44, standardized in P-38J/K Pilot's Manual Summer '44]
• Combat Doctrine Development / Training
  • Rotate experienced pilots to Transitioning units for tactical dissemination [Late Summer '43]
  • Include P-38 in Tactical Training Schools in England [Winter/Spring '44]
  • Establish Tactical Training Schools in Australia (later New Guinea, Solomons, etc) [Summer '44]" EverKing's list of improvements from post #1940.

Looking at this very comprehensive list of ATL improvements to the P-38 it's difficult to see how what more could have been done. I think you can't get any more significant increases in performance in a propeller driven airplane by this point. Which leads to the question, could any of these ATL improvements been reached earlier in another ATL where the XP-38 isn't destroyed on the record attempt flight?

Of course it's impossible to answer that with any certainty. An alternate TL of an ATL. But it does spawn some speculations.

Many of the improvements listed could not have been achieved much earlier then in this ATL because they weren't available until later. Most notable the more powerful Allison engines. Paddle bladed high activity propellers. Higher speed turbochargers. The technology to make bigger plexiglass shapes.

But there were the other improvements that the 1939/1940 technology would have supported. For example the NACA design changes. Dive recovery flaps. Hydraulically boosted ailerons. And a better fuel management system. And a proper fighter plane joystick, dammit. Having an earlier and better P-38 may have led to more British interest and purchasing of the Lightning in 1940/1941 pushing Lockheed to implement improvements for the RAF before the U.S. entry into the war. Hopefully including the British requesting an all 20mm cannon armament fit.

Which leads to this speculation concerning EverKing's almost perfect ATL NACA P-38. The only substantial way I think the 1943/1944 NACA P-38 could have been further improved would have been by moving the cockpit forward about 1.5 feet or so. And then fitting 4 20mm cannons (hopefully they're reliable ones) in the lower belly behind the cockpit with the forward most barrels placed just aft of the nose gear and with about 250 to 300 rounds per gun. Imagine that punch with a gyrostabilized gunsight.

 

[EverKing]

Dive recovery flaps. Hydraulically boosted ailerons.

Dive recovery flaps were developed in '42 by Irv Culver at Lockheed (progenitor of the Skunk Works nickname), first tested in the 16-foot high-speed wind tunnel at Ames. See the Introduction of This Report (PDF Download).

(Practical) Boosted ailerons were developed by Lockheed engineer Bob Richolt in July of '43. He developed (and patented) a new type of hydraulic servomotor that could progressively increase force based on the input via a bell crank rather than directly activating the hydraulics as either on/off.

EDIT: Here's the patent (filed in Sept '43, granted in Mar '48).

So, these two still wouldn't have been available until '42/'43.

Which leads to this speculation concerning EverKing's almost perfect ATL NACA P-38. The only substantial way I think the 1943/1944 NACA P-38 could have been further improved would have been by moving the cockpit forward about 1.5 feet or so. And then fitting 4 20mm cannons (hopefully they're reliable ones) in the lower belly behind the cockpit with the forward most barrels placed just aft of the nose gear and with about 250 to 300 rounds per gun. Imagine that punch with a gyrostabilized gunsight.

Which is basically what Vultee settled on ITTL for the XP-81

 

[Draconis]

After having posted this link in the Munich Shuffle thread it occurred to me that the NACA P-38 readers may appreciate the assessments of and comments on the OTL P-38 as compared to other fighters by some of the pilots who flew those planes in WW2. The link connects to an old (1996) archived discussion forum. With commentary from some of the P-38 pilots. Considering that these men are now gone the discussion is an irreplaceable and vivid insight into the recent past. And an informative and myth dispelling look at the P-38 Lightning in the ETO.

The P-38 (C.C. Jordan; MakinKid; CDB100620)

 

[tomo pauk]

And an informative and myth dispelling look at the P-38 Lightning in the ETO.

What myth would that be (or more of them) - the article is rather long...

 

[Draconis]

What myth would that be (or more of them) - the article is rather long...

This is one sample from the article discussing the relative merits of the P-38 compared to the P-51. Including a differing opinion of why the 8th Air Force replaced the P-38 with the P-51.

"Sidney described the Mustang as a super P-40. He did not consider it in
the same class with the P-38. He often said that the P-40 and P-51
represented pre-war air combat thinking, and that the P-38 represented the
future. That's a broad statement, and I can't recall his specific reasons
for making it, but it does give you a sense of his feeling for the
aircraft.

Sidney said that were he flying the P-38 in Europe he could have shot down
more planes than he did. On more than one occasion, for example, he noted
that while he was closing in to wing-gun range an FW would execute one of
its fabulous snap-rolls and split-S away. Had he been in a P-38 he could
have opened fire seconds earlier, gained strikes for certain, possibly
destroying the aircraft.

Sidney believed the poor showing of the P-38 in the ETO was the result of
AAF brass, who, pre-war were wedded to the unescorted heavy bomber
concept, and didn't dare admit, in the face of terrible bomber losses,
that they had a perfectly capable figher capable of escorting their
bombers from day one to the farthest target they ventured to--but they
chose not to use it. Instead, they mutually, if unconsciously, fixed on
every reason they could find to discount the P-38 as a capable fighter.
They could then say they had no choice but to go unescorted until the P-51
came along. Had they said, Yeah, we had a good escort fighter in the P-38
but decided not to use it, congressional committees would have been
demanding to know who screwed the pooch (his phrase)." From "The P-38 as best."

 

[tomo pauk]

This is one sample from the article discussing the relative merits of the P-38 compared to the P-51. Including a differing opinion of why the 8th Air Force replaced the P-38 with the P-51.

Thanks.
The way I read it, it is much more of 'if only I was there...' stuff, rather than 'dispelling a myth'. He is also wrong on that 8th AF bombers were not escorted by P-38s, or on the notion that there was no bombers' escort before P-51(B) arrived.
Too bad that people that heap praises on their prefered A/C seem to never also list the shortcomings that aircraft had, and P-38 had a host of serious of these.

 

[Draconis]

I'm going to post again a link to a website that contains very detailed close up pictures of a partially assembled P-38L. The link takes you to a cutaway diagram which show various red spots on places that when clicked on bring up a highly detailed photographs of those places on the P-38. These photographs are scrollable by mouse and can be zoomed in and out. If one wants to see how crowded and complex this airplane is this is the way to go. Check out how complex the fuel and hydraulic plumbing is for example.

http://vintagetin.net/P-38L/#

 

[Driftless]

I'm going to post again a link to a website that contains very detailed close up pictures of a partially assembled P-38L. The link takes you to a cutaway diagram which show various red spots on places that when clicked on bring up a highly detailed photographs of those places on the P-38. These photographs are scrollable by mouse and can be zoomed in and out. If one wants to see how crowded and complex this airplane is this is the way to go. Check out how complex the fuel and hydraulic plumbing is for example.

http://vintagetin.net/P-38L/#

Fascinating views! Just creating the photo map was a hell of an undertaking.

 

[Draconis]

This link takes you to the detailed and scrollable photo of the P-38's gun bay. The breeches and magazines have been removed. And a few other things too. It illustrates how difficult it would have been to install 3 or 4 20mm cannons and an adequate ammunition supply for them in this narrow area. Possibly if the nose gear hydraulic motor was relocated and the two hydraulic reservoirs relocated enough space would have been freed up to put 2 20mm cannons, one on each lower outer edge of the gun bay with the rearmost one with it magazine filling the whole width. The second 20 mm placed forward enough so it's full width magazine is located just forward of the first one. That means the guns are staggered about a foot. That still leaves some room for more guns. But how many and what size?

http://vintagetin.net/P-38L/P-38L-5InsideGunBay180620/

 

[EverKing]

Too bad that people that heap praises on their prefered A/C seem to never also list the shortcomings that aircraft had, and P-38 had a host of serious of these.

Quoted for truth. I'm under no illusion of the issues with P-38. In fact the entire exercise in this thread has been to find way to correct as many of those issue as possible in satisfactory ways.

That said, I think it often goes pretty far the other direction too--that people tend to be unfairly and overly critical of airplanes that are not their preferred platform. Again, the P-38 may be a prime example in how little credit it is given by the Mustang Posse even though P-38s out-numbered Mustangs in the 8th AF until just a few weeks before D-Day which means Lightnings did a lion's share of the heavy lifting in those first months of '44 when they were outnumbered by a highly experienced Luftwaffe. It's easy to look at Kill Ratios and say "this fighter was better that that one" but that is only part of the story. When one considered the full gamut of variations between the fight the Lightnings faced in late '43/early'44 verses the fight the Mustangs pushed in late'44 and '45 you'll find they are worlds apart. Sure, the Lightning (especially before the J-25) had some severe performance (dive & roll) and comfort penalties and I don't think anyone would say that, as delivered and operated, the P-38 was in all ways superior to the P-51; but it was still the primary platform in early '44 that really started to destroy the Luftwaffe and prepare the way for the Invasion. The Mustang did more than its share of hunting as well, of course, and it reaped all the benefits of the early hard fight by being deployed by the hundreds against a depleted and increasing ill-trained Luftwaffe through the end of the war. So, as great as the P-51 was, the P-38 does deserve a lot more credit in Europe than it is often given by cursory histories.

 

[EverKing]

I'm going to post again a link to a website that contains very detailed close up pictures of a partially assembled P-38L. The link takes you to a cutaway diagram which show various red spots on places that when clicked on bring up a highly detailed photographs of those places on the P-38. These photographs are scrollable by mouse and can be zoomed in and out. If one wants to see how crowded and complex this airplane is this is the way to go. Check out how complex the fuel and hydraulic plumbing is for example.

http://vintagetin.net/P-38L/#

Loving this! Thanks for sharing.

 

[tomo pauk]

Quoted for truth. I'm under no illusion of the issues with P-38. In fact the entire exercise in this thread has been to find way to correct as many of those issue as possible in satisfactory ways.

An excellent thread indeed

That said, I think it often goes pretty far the other direction too--that people tend to be unfairly and overly critical of airplanes that are not their preferred platform. Again, the P-38 may be a prime example in how little credit it is given by the Mustang Posse even though P-38s out-numbered Mustangs in the 8th AF until just a few weeks before D-Day which means Lightnings did a lion's share of the heavy lifting in those first months of '44 when they were outnumbered by a highly experienced Luftwaffe. It's easy to look at Kill Ratios and say "this fighter was better that that one" but that is only part of the story.When one considered the full gamut of variations between the fight the Lightnings faced in late '43/early'44 verses the fight the Mustangs pushed in late'44 and '45 you'll find they are worlds apart.

The P-51 were present also in the 9th AF, serving as escort when needed.
The number of escorts during the 2nd day of the big week was, per Wikipedia (verbatim) ... 69 P-38s, 542 Eighth and Ninth Air Force P-47s and 68 Eighth and Ninth Air Force P-51s.
Number of P-38s was down from 94 as deployed on the day 1 of the Big Week - a ~30% lower number(!); 73 P-51s were deployed on day 1.

I agree that kill ratios can be misleading, ditto for kill claims, however, against the same stock of LW pilots and with the similar ( and meager) number of fighters, P-51s claimed 14-1-4, while P-38s claimed 0-1-0 (again, per Wikipedia) on the day 2. Yes, P-51 losses were 3 A/C, one P-38 damaged beyond repair. On the 3rd day, P-51s claim 19-1-10, vs. P-38s claiming only one (again the P-51s sustaining losses greater than the P-38s).
For the last day, Wikipedia entry:
Escort is provided by 73 P-38s, 687 Eighth and Ninth Air Force P-47s and 139 Eighth and Ninth Air Force P-51s; the P-38s claim 1-2-0 Luftwaffe aircraft, 1 P-38 is damaged beyond repair; the P-47s claim 13-2-10 Luftwaffe aircraft, 1 P-47 is lost and 6 damaged, 1 pilot is MIA; the P-51s claim 12-0-3 Luftwaffe aircraft, 2 P-51s are lost and 1 damaged beyond repair, 2 pilots are MIA.

P-51 was the one doing heavy lifting in the "kill the LW category" from the early 1944, along with P-47 (despite the often insufficient range), with P-38 coming as 3rd best. Please note that on the last day of the Big Week the P-51s outnumber the P-38s by almost 2:1.

The Mustang did more than its share of hunting as well, of course, and it reaped all the benefits of the early hard fight by being deployed by the hundreds against a depleted and increasing ill-trained Luftwaffe through the end of the war. So, as great as the P-51 was, the P-38 does deserve a lot more credit in Europe than it is often given by cursory histories.

We should probably give a lot more credit to the P-47, as the 1st USAAF type really hitting the LW in the ETO already in 1943. P-51s deployed in hundreds also benefitted by the deeds of the P-51s deployed in dozens in February of 1944.

 

[phx1138]

We should probably give a lot more credit to the P-47, as the 1st USAAF type really hitting the LW in the ETO already in 1943. P-51s deployed in hundreds also benefitted by the deeds of the P-51s deployed in dozens in February of 1944.

Agreed, & I say that as an avowed P-38 buff.

Too many historiographers focus on the P-51 and seem to think there were no escorts before it. There may not have been any able to make the Berlin round trip (& the lack of drop tanks that would have made that false is another thread ), but it's not as if the bombers went out alone on every mission--just the longer (longest) ones; indeed, AIUI, only on the longest parts of those, even.

The P-38 gets way, way too little credit.

I'd love to game it out, if it was possible: eliminate the P-47s & P-51s & see how much difference an all-P-38 escort force would have made.

(If I was was writing it... {See "avowed" above.})

 

[tomo pauk]

Too many historiographers focus on the P-51 and seem to think there were no escorts before it. There may not have been any able to make the Berlin round trip (& the lack of drop tanks that would have made that false is another thread ), but it's not as if the bombers went out alone on every mission--just the longer (longest) ones; indeed, AIUI, only on the longest parts of those, even.

Unfortunately, the P-47 was unable to escort the 8th AF bombers to Berlin before the -25 and -26 arrived some time in mid-1944 (despite what Greg says in his video), since those have had the increased internal fuel capacity to 370 gals from 305 gals, as well as the proper drop tanks facility.

 

[EverKing]

P-51 was the one doing heavy lifting in the "kill the LW category" from the early 1944, along with P-47 (despite the often insufficient range), with P-38 coming as 3rd best. Please note that on the last day of the Big Week the P-51s outnumber the P-38s by almost 2:1.

Conceded.

But, one has to wonder how the P-38 would have done if fielded with more experienced crews (the 55th and 20th FG, the first P-38 groups in the 8AF were both Green when they arrived in theatre) and better doctrine. The major factors holding the P-38 kill-counts back on Big Week 1 & 2 were lack of crew confidence due to early problems in their first month or two of combat as a result of lack of experience and poor doctrine which, even during Big Week, resulted in the Lightnings generally staying closer to the Bomber Streams rather than actively hunting the enemy down. By Big Week, the damage had already been done to these Groups and they never really recovered.

It does support your point, though, (and override my erred assessment to the contrary) that the P-51 was immediately having a bigger impact even with fewer active in the 8AF directly at the time.

We should probably give a lot more credit to the P-47, as the 1st USAAF type really hitting the LW in the ETO already in 1943. P-51s deployed in hundreds also benefitted by the deeds of the P-51s deployed in dozens in February of 1944.

Oh, absolutely. I wasn't deliberately excluding the Thunderbolt (which I adore, btw) but was just focusing on the Mustang because that is where the argument usually lies.

The P-38 gets way, way too little credit.

I think this is the main thrust of what I'm trying to say. The P-51 was the right system arriving at the right time under the right leadership and the right doctrine. The P-38 may not have the kill count or the reputation among the historians but ask the bomber crews and they loved seeing the P-38 more than any other. They stayed with the Bombers, often their mere presence holding the enemy off, which the crews could see circling the distance. I've read a few War Journals from the 91st and 100th BG(H) and the P-38s are always celebrated while they sometimes would make comments about the Mustangs either not showing up or just disappearing and leaving them alone (which, in the Mustang pilots' defense, is what they were ordered to do--hunt the Germans away from the bombers). I wouldn't say the Lightning was underrated so much as it tends to be underappreciated.

Still, as it was deployed IOTL, it was far from the ideal platform for High Altitude combat in Western Europe. It's flaws were too many and always seemed to be exacerbated in the 8AF where they were mitigated and overcome in all other theatres and uses (including in the 9AF).

 

[Draconis]

This link takes you to the detailed and scrollable photo of the P-38's gun bay. The breeches and magazines have been removed. And a few other things too. It illustrates how difficult it would have been to install 3 or 4 20mm cannons and an adequate ammunition supply for them in this narrow area. Possibly if the nose gear hydraulic motor was relocated and the two hydraulic reservoirs relocated enough space would have been freed up to put 2 20mm cannons, one on each lower outer edge of the gun bay with the rearmost one with it magazine filling the whole width. The second 20 mm placed forward enough so it's full width magazine is located just forward of the first one. That means the guns are staggered about a foot. That still leaves some room for more guns. But how many and what size?

http://vintagetin.net/P-38L/P-38L-5InsideGunBay180620/

The British developed a slightly shorter barreled version of the HS 20mm with a total length of 7 feet 2 inches. Using these shorter guns it may have been possible to fit 4 20mm cannon into the P-38s' nose using the modifications mentioned in my previous posting. The shorter barreled guns won't have the muzzles sticking out so far into the air stream. Reducing drag and the over chilling of the guns. There is a small reduction of muzzle velocity with the shorter barrels but the Mark 5 gun could still reach 2800 feet per second which is still pretty good for a WW2 20mm airplane cannon.

I would guess the ammo capacity would vary somewhat with each gun as the magazines in this arrangement would have their width reduced going from the rearmost to the front most as the nose narrows and as the available width is further reduced going forward by the space used by the breeches and barrels of the other guns. Maybe resulting in the rearmost magazine carrying about 250 rounds. Then reducing in steps of about 20 rounds down to about 190 for the front most magazine. A rough guestimate based on mounting the guns on the inside walls of the nose bay, not in the centre as was done for OTL's single 20mm. Thereby allowing the magazines to use all possible available space in a full width placement as described in my previous posting. And here again is the link from that previous posting showing the internal view of the P-38 (same size I think whether OTL or NACA ATL) nose gun bay. This is the only way I can see where it would've been possible to fit 4 20mm cannon in the P-38's nose and still have a reasonable ammunition capacity too.

http://vintagetin.net/P-38L/P-38L-5InsideGunBay180620/

 

[EverKing]

The British developed a slightly shorter barreled version of the HS 20mm with a total length of 7 feet 2 inches. Using these shorter guns it may have been possible to fit 4 20mm cannon into the P-38s' nose using the modifications mentioned in my previous posting. The shorter barreled guns won't have the muzzles sticking out so far into the air stream. Reducing drag and the over chilling of the guns. There is a small reduction of muzzle velocity with the shorter barrels but the Mark 5 gun could still reach 2800 feet per second which is still pretty good for a WW2 20mm airplane cannon.

I would guess the ammo capacity would vary somewhat with each gun as the magazines in this arrangement would have their width reduced going from the rearmost to the front most as the nose narrows and as the available width is further reduced going forward by the space used by the breeches and barrels of the other guns. Maybe resulting in the rearmost magazine carrying about 250 rounds. Then reducing in steps of about 20 rounds down to about 190 for the front most magazine. A rough guestimate based on mounting the guns on the inside walls of the nose bay, not in the centre as was done for OTL's single 20mm. Thereby allowing the magazines to use all possible available space in a full width placement as described in my previous posting. And here again is the link from that previous posting showing the internal view of the P-38 (same size I think whether OTL or NACA ATL) nose gun bay. This is the only way I can see where it would've been possible to fit 4 20mm cannon in the P-38's nose and still have a reasonable ammunition capacity too.

http://vintagetin.net/P-38L/P-38L-5InsideGunBay180620/

The US actually did copy the Mk.V as the A/N M3 Cannon, which in turn was adopted by the (post-war) USAF as the M24 which added electrical cocking (and re-cocking in the event of failure in flight) to it. The US M3 ("20mm Automatic Gun M3") was only 77.7" OAL (6' 5.7" or 1.97m) with a total weight of 99.5 lb (45.1 kg) including the cradle but not including the feed/de-linker mechanism which was another 15.5 lb (7 kg). Also, you'd have to add the electric trigger (3.5 - 5 lb depending on model) and charger (between 2.5 lb and 4.3 lb depending on model whether pneumatic, manual, or hydraulic...I do not have the data on the electric charger for the M24 at hand so can't speak to that) and an optional 1 lb electric heater. It offered a ROF of 650-800 RPM at a MV of 2730 fps (832 m/s). This according to TM 9-229, the official Technical Manual for the weapon updated 18 March 1947 and published 20 June 1947 from an original released 11 Jan 1945.

Unfortunately, this came too late to the US be used in the War and still didn't fix the headspace issues that caused so much reliability trouble.

 

[Salvare7097]

So I just had an interesting thought if you get a decent turboprop version of the P-38 you could potentially see it continue service as the A–38 to present day. Maybe every five-ten years update electronics and avionics. Especially after World War II the US isn’t going to do much pier on pier fighting. The plane could very much remain the COIN aircraft.

Remember the P-51 saw service as a CAS aircraft in Korea as and it is not as well-suited as the P-38 was for the role. If you get farsighted enough AAF and later AF brass. Hell you don’t even need that you just need brass to CAS as secondary notice how good the P-38 was at close air support and decide to save money by keeping the P-38 re-engineing and updating the avionics and electronics.

I’m not joking about seeing a potential CAS variant flying to this day in USAF Service. Or hell you could potentially throw a curveball in by having the army keep CAS and then have them keep P-38 or rather this case A-38 production going. CAS aircraft don’t need to be fast they don’t need to be particularly stealthy you could just go jamming root of countermeasures. CAS aircraft just need good loiter time.

 

[RanulfC]

So I just had an interesting thought if you get a decent turboprop version of the P-38 you could potentially see it continue service as the A–38 to present day. Maybe every five-ten years update electronics and avionics. Especially after World War II the US isn’t going to do much pier on pier fighting. The plane could very much remain the COIN aircraft.

Remember the P-51 saw service as a CAS aircraft in Korea as and it is not as well-suited as the P-38 was for the role. If you get farsighted enough AAF and later AF brass. Hell you don’t even need that you just need brass to CAS as secondary notice how good the P-38 was at close air support and decide to save money by keeping the P-38 re-engineing and updating the avionics and electronics.

I’m not joking about seeing a potential CAS variant flying to this day in USAF Service. Or hell you could potentially throw a curveball in by having the army keep CAS and then have them keep P-38 or rather this case A-38 production going. CAS aircraft don’t need to be fast they don’t need to be particularly stealthy you could just go jamming root of countermeasures. CAS aircraft just need good loiter time.

Your biggest issue it post-war politics. If Truman is still going to be President then the Air Force will not have the budget to keep more than one or two type of combat aircraft through 1950. (And assuming Korea still happens TTL) The P-47 was a wonderful COIN aircraft but it came down to a choice of it or the P-51 and the P-51 was the better 'interceptor' aircraft. (The Air Force bemoaned the use of the P-51 as a COIN as it was far more fragile and easily damaged by ground fire than the P-47)

A case 'might' be made for the P-38 rather than the P-51 but I doubt it.

Randy