The P-38 was used most extensively and successfully in the Pacific theater, where it proved ideally suited, combining excellent performance with exceptional range and the added reliability of two engines for long missions over water.
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Kurt BĂĽhligen, third highest scoring German pilot on the Western front with 112 victories, recalled later: "The P-38 fighter (and the B-24) were easy to burn. Once in Africa we were six and met eight P-38s and shot down seven. One sees a great distance in Africa and our observers and flak people called in sightings and we could get altitude first and they were low and slow."
[69] General der Jagdflieger Adolf Galland was unimpressed with the P-38, declaring "it had similar shortcomings in combat to our
Bf 110, our fighters were clearly superior to it.""
Lockheed P-38 Lightning - Wikipedia
The P 38 is an early stage WWII plane. But it is indeed a long range fighter.
It failed so badly that it stopped almost all the cargo planes and supply ships from getting to port. It failed so badly that it took out many runways that the 109 operated from. What your German Pilot was probably talking about was hitting it when it was loaded down with bombs on a bombing mission. Now, have the 109 meet it at 15K with it not carrying the bombs.
Early on, many of the 38 pilots were extremely green on twin engine birds. They trained on single engine trainers. And they were met with 11-1 odds against them. The areas it operated in NA meant it didn't have any cover when on the bombing runs. This period was what I call the "Meat Grinder". The introduction of the P-47 in NA was a huge improvement and moved the P-38 into top cover when operating with the P-47s. As the number of P-47s started showing up, the odds changed fast until the allied fighters in NA ended up with a 11-1 ratio in their favor. Each day, the Luftwaffe available air fields were slowly pushed back until the Spit, P-40 and Hurricane could no longer operate over enemy territory. This left the P-38 on it's own until the P-47s showed up. It's not that the P-38 was a bad bird. It was that it was so overwhelmed that many were lost. But as the months went on, the Luftwaffe was whittled down a little each day.
The short comings were trained out once they figured out that the P-38 pilots needed special training. The Piggyback P-38 was a godsend where the pilots trained on a real P-38 instead of just being dumped into the seat of the single seater.
Your comment that the P-38 was an early warbird was correct. But so was the 109. Both just got better through constant upgrades. But in early 1943 the P-38 out shined the 109. It's equal was the 190 for a few months. Then the P-38J-LO-25 (dive brakes) hit the skies in numbers and the 190 was left out to dry. Until the advent of the P-51D, the main high altitude long ranged fighter was the P-38J-LO-15 (no dive brakes) with it's fowler flaps. The way the 109 and 190 avoided their lunches from being eaten was by going in to a high speed dive that the P-38 Pilots were forbidden to follow. When the -25 hit (and the upgrades to the -15 to -25 standard, there were quite a few luftwaffe pilots that died when they tried that same tried and true maneuver. And, for once, the P-38 Pilots got the training they needed to excel in their birds. It wasn't just the P-38 that got better, it was also the P-51 and the P-47. In the end, those 3 operated over enemy held areas with impunity. All 3 were involved in the early 1944 fighter sweeps that all but wiped out the Luftwaffe.
This is why I listed only those 3. The impact those 3 had for the war effort was more pronounced than they other fighters. There wasn't enough P-51B/Cs to take the P-38 out of the bomber escort business. When the P-51D arrived, it arrived with a vengence in numbers with over 8000 produced as compared to the C/B version of about 3000. But the C/B versions had some pretty serious teething problems that were, for the most part, ironed out in the D.
Until the P-38J, there were only 2210 P-38s made (F, G, H). There were many more P-47s built in 1943 than all the P-38s and P-51B/Cs combined.
BTW, the Luftaffen Pilots all claimed that the 190 was the equal to the P-51D. Going by what they said you can chalk it up as Public Relations for their pilots.