Ok lets get started on the P-38, bit by bit.
First the astonishing inability of Lockheed to upgrade the cooling system (inc intercoolers) to deal wth the greater power developed by Allison.
This meant the performance was officialy fixed across multiple models:
"The maximum speed and climb performance of the various P-38 models is, however, something of a mystery. Although rated takeoff power from the XP-38 through the P-38H increased from 1150 bhp to 1425 bhp the Tactical Planning Charts issued by Wright Field show all variants with a similar speed. Closer examination of the charts will reveal that all P-38 powerplants, through the H model, are limited to 1150-1240 bhp, due to "inadequate cooling." "
The P-38 Lightning
Now can you imagine if Suprmarine, Republic, DH, NA (etc) had said "ok you have upgraded engines but because we cannot be bothered to upgrade the cooling system so you can't use the perfomance"? Heads would have rolled but somehow Lockheed got a pass on that.
Now this, plus the extreme (and unnecessary) complexity of the controls was probably the major factor in the incredible engine unreiability suffered when in service in the 8th. What happened was many undid the stops on the throttle/boost controls and blew their engines up through overheating. That makes much more sense that the claim that the 'low' temps seperated the lead from the fuel, because the P-38 suffered from excessive temps, not too low ones. Amazingly other planes with much hgher intercolooling didn't suffer from this.
Even without this unofficial tweeking they were easy engines to blow because of poor controls and cooling (not Allison's fault):
"As a typical case to demonstrate my point, let us assume that we have a pilot fresh out of flying school with about a total of twenty-five hours in a P-38, starting out on a combat mission. He is on a deep ramrod, penetration and target support to maximum endurance. He is cruising along with his power set at maximum economy. He is pulling 31" Hg and 2100 RPM. He is auto lean and running on external tanks. His gun heater is off to relieve the load on his generator, which frequently gives out (under sustained heavy load). His sight is off to save burning out the bulb. His combat switch may or may not be on. Flying along in this condition, he suddenly gets "bounced", what to do flashes through his mind. He must turn, he must increase power and get rid of those external tanks and get on his main. So, he reaches down and turns two stiff, difficult gas switches {valves} to main - turns on his drop tank switches, presses his release button, puts the mixture to auto rich (two separate and clumsy operations), increases his RPM, increases his manifold pressure, turns on his gun heater switch (which he must feel for and cannot possibly see), turns on his combat switch and he is ready to fight.
At this point, he has probably been shot down or he has done one of several things wrong.
Most common error is to push the throttles wide open before increasing RPM. This causes detonation and subsequent engine failure. Or, he forgets to switch back to auto rich, and gets excessive cylinder head temperature with subsequent engine failure."
"The large number of engine failures deep inside enemy airspace exacerbated the problem, and the aggregate exchange rate, accidents inclusive, dropped to about 1:1.5 in favour of the Lightning by 1944.".
Now that is the claims/loss rate, given the usual 2:1, or 3:1 overclaiming rate P-38s were dying in larger numbers than they were killing
"To aggravate these problems, inadequate cockpit heating resulted in severe pilot frostbite, while the Luftwaffe quickly learned about the compressibility problems in dives, with German pilots evading the P-38s by executing a split-S at high speed. The initial roll rate was not spectacular and the easily recognized planform provided the Luftwaffe with yet another advantage to play."
"Poor serviceability and engine problems meant that initially 50 or less aircraft were available for such missions, including the first escorts over Berlin"
Der Gabelschwanz Teufel - Assessing the Lockheed P-38 Lightning
Then the miserable mach limit, a problem right from the beginning:
"The XP-38 airframe proposal carried 400 USG of fuel internally, employed a near to symmetrical NACA 23016/4412 section and grossed out at 11,400 lb. Designed for 1,150 HP engines, the Model 22 was built to exceed 360 kts at altitude, stunning performance for the time. Johnson had at the time commented in detail on the possibility of compressibility affecting the handling of the aircraft, this was later to prove to be a major issue."
"The 322 (RAF version) had by that time also demonstrated problems due compressibility in dives which caused 'Mach tuck', a severe nose down pitching moment due to the aft of the CoP. This often led to the breakup of the aircraft and usually, loss of the pilot".
Now the P-47 also had a poor mach limit (though better than the P -38) but you had a better chance of survival in it provided the pilot had enough altitude and kept their head until a lower altitude was reached. The problem was the difference between the max level speed, lawn dart speed and 'tear the plane to shreds' speed were much too close in the P-38.
Now the eventually fitted dive recovery flaps saved a lot of iives, not because they improved the mach limit by much (they didn't) but, provided there was enough altitude, they alowed a gentle pull out that didn't overstress the airframe.
So there are two major long known about problems that Lockheed took ages to alleviate, with the third, control complexity, never fixed.
First the astonishing inability of Lockheed to upgrade the cooling system (inc intercoolers) to deal wth the greater power developed by Allison.
This meant the performance was officialy fixed across multiple models:
"The maximum speed and climb performance of the various P-38 models is, however, something of a mystery. Although rated takeoff power from the XP-38 through the P-38H increased from 1150 bhp to 1425 bhp the Tactical Planning Charts issued by Wright Field show all variants with a similar speed. Closer examination of the charts will reveal that all P-38 powerplants, through the H model, are limited to 1150-1240 bhp, due to "inadequate cooling." "
The P-38 Lightning
Now can you imagine if Suprmarine, Republic, DH, NA (etc) had said "ok you have upgraded engines but because we cannot be bothered to upgrade the cooling system so you can't use the perfomance"? Heads would have rolled but somehow Lockheed got a pass on that.
Now this, plus the extreme (and unnecessary) complexity of the controls was probably the major factor in the incredible engine unreiability suffered when in service in the 8th. What happened was many undid the stops on the throttle/boost controls and blew their engines up through overheating. That makes much more sense that the claim that the 'low' temps seperated the lead from the fuel, because the P-38 suffered from excessive temps, not too low ones. Amazingly other planes with much hgher intercolooling didn't suffer from this.
Even without this unofficial tweeking they were easy engines to blow because of poor controls and cooling (not Allison's fault):
"As a typical case to demonstrate my point, let us assume that we have a pilot fresh out of flying school with about a total of twenty-five hours in a P-38, starting out on a combat mission. He is on a deep ramrod, penetration and target support to maximum endurance. He is cruising along with his power set at maximum economy. He is pulling 31" Hg and 2100 RPM. He is auto lean and running on external tanks. His gun heater is off to relieve the load on his generator, which frequently gives out (under sustained heavy load). His sight is off to save burning out the bulb. His combat switch may or may not be on. Flying along in this condition, he suddenly gets "bounced", what to do flashes through his mind. He must turn, he must increase power and get rid of those external tanks and get on his main. So, he reaches down and turns two stiff, difficult gas switches {valves} to main - turns on his drop tank switches, presses his release button, puts the mixture to auto rich (two separate and clumsy operations), increases his RPM, increases his manifold pressure, turns on his gun heater switch (which he must feel for and cannot possibly see), turns on his combat switch and he is ready to fight.
At this point, he has probably been shot down or he has done one of several things wrong.
Most common error is to push the throttles wide open before increasing RPM. This causes detonation and subsequent engine failure. Or, he forgets to switch back to auto rich, and gets excessive cylinder head temperature with subsequent engine failure."
"The large number of engine failures deep inside enemy airspace exacerbated the problem, and the aggregate exchange rate, accidents inclusive, dropped to about 1:1.5 in favour of the Lightning by 1944.".
Now that is the claims/loss rate, given the usual 2:1, or 3:1 overclaiming rate P-38s were dying in larger numbers than they were killing
"To aggravate these problems, inadequate cockpit heating resulted in severe pilot frostbite, while the Luftwaffe quickly learned about the compressibility problems in dives, with German pilots evading the P-38s by executing a split-S at high speed. The initial roll rate was not spectacular and the easily recognized planform provided the Luftwaffe with yet another advantage to play."
"Poor serviceability and engine problems meant that initially 50 or less aircraft were available for such missions, including the first escorts over Berlin"
Der Gabelschwanz Teufel - Assessing the Lockheed P-38 Lightning
Then the miserable mach limit, a problem right from the beginning:
"The XP-38 airframe proposal carried 400 USG of fuel internally, employed a near to symmetrical NACA 23016/4412 section and grossed out at 11,400 lb. Designed for 1,150 HP engines, the Model 22 was built to exceed 360 kts at altitude, stunning performance for the time. Johnson had at the time commented in detail on the possibility of compressibility affecting the handling of the aircraft, this was later to prove to be a major issue."
"The 322 (RAF version) had by that time also demonstrated problems due compressibility in dives which caused 'Mach tuck', a severe nose down pitching moment due to the aft of the CoP. This often led to the breakup of the aircraft and usually, loss of the pilot".
Now the P-47 also had a poor mach limit (though better than the P -38) but you had a better chance of survival in it provided the pilot had enough altitude and kept their head until a lower altitude was reached. The problem was the difference between the max level speed, lawn dart speed and 'tear the plane to shreds' speed were much too close in the P-38.
Now the eventually fitted dive recovery flaps saved a lot of iives, not because they improved the mach limit by much (they didn't) but, provided there was enough altitude, they alowed a gentle pull out that didn't overstress the airframe.
So there are two major long known about problems that Lockheed took ages to alleviate, with the third, control complexity, never fixed.