Toward the end of World War II, while the P-51 Mustang was busy helping to win the air war over Europe, an entirely different high-altitude interceptor mastered the skies over the Pacific. The P-38 was an innovative design for extreme speed and altitude that required a lot of bugs be wrung out of it before it became an effective weapon against the Japanese A6M “Zero.”
Compressibility effects that locked up control surfaces, engine failures and supercharger glitches caused the plane to be labeled “dangerous” after a large number of crashes when the plane was introduced to combat. As described in the video, these all got fixed, and the plane was eventually credited by its pilots with winning the air war in the Pacific.
However, one glitch that never got fixed lived on to torment future aircraft designers, like Bob Pond with his Lightning-like “Pond Racer,” shown below.
It was a subtle glitch and one that never caused any problems except in certain conditions that caused the plane to enter a “flat spin” condition. The flat spin is a condition that terrifies all pilots because of the large number of them killed by it. Normally, rudder control and throttle can be used to get out of a spin or to prevent it, and that works most of the time. But some aircraft, especially those with very large “moments of inertia” around the vertical axis, like the P-38 and most “wide” or “squarish” planes, have a fatal tendency to stick like glue in a flat spin, resisting all efforts to get out of it. Further, it’s hard to eject safely from an airplane in such a spin. So, not a good thing.
Later aircraft of similar planforms, like the McDonnell Douglas F-15, solved this problem with very large vertical stabilizers (tail fins). But the P-38 was designed at a time when speed was the absolute driving factor. It needed to go 400 mph to beat the Japanese fighters, so it’s tails were made small and aerodynamic. Even the Pond Racer did not really have adequate tail surface area to keep it out of spins, though with its three tails, it was better than the P-38.
Few pilots talk about the flat spin problem with the P-38, and it’s not mentioned in historical works, like the video above. Having established itself as a heroic icon, the plane really doesn’t need to be criticized by its admirers. Who, in his right mind, would criticize the slight wrinkles that Raquel Welch seems to have picked up now that she’s in her 70s? No gentleman, certainly. It would be absurd to criticize such an iconic beauty, who remains so, even to this day.
And I’d certainly be the last to criticize. Yet, I do mention it, if only because it’s something to keep in mind for the future. I wouldn’t even be aware of it except for the whispers of a P-38 pilot on a dusty runway near Petaluma, California back in the 1990s. He’d taken up ultralight flying, for fun, in his last years, but he’s long since gone on to the clear skies of the next life. He knew I was an aerospace engineer at Lockheed at the time, and he told me about the problem like he expected me to fix it in future models. “Kelly made the vertical stabs too damn small. I lost two buddies because of it. Get on that.” Heh. I’m sure he’s already told Kelly Johnson himself since then. But I’ll keep it in mind.