LeVier could dive a P-38 and recover while hitting speeds high enough to take panels off the plane.
What several pilots told me is that most of the compression losses were actually from guys trying to see what happened when you deliberately pushed past what the placard said. Meaning few accidentally compressed and couldn't recover. They also said that many times the failure to recover was evidently due to the fact that pilots panicked and didn't know what to do. The yoke would literally beat the crap out of you.
The compression losses during testing were most often due to failure of abused parts.
Kelly Johnson said he was certain a spring tab operating link failure is what actually killed Ralph Virden. It allowed the travel limit to be exceeded and snapped the tail off because the stress exceeded 9G, and Johnson said it may have exceeded 15G. The part that failed was designed to increase the leverage the pilot could apply to the elevator in order to effect a pullout. Virden was warned to be careful at low altitudes and high speeds, as he could easily exceed the design limits. At around 3000 feet and over 300MPH, Johnson said that the link broke, and allowed the elevator to go to full deflection. The plane Virden was in was the first YP-38, and the one with the most hours. It had for a while been the only one flying, and as such had logged a great number of hours. It was then committed to the dive and compressibility tests, after several more "Yippees" became available for other testing.
When Ben Kelsey lost a P-38 in dive testing it was because the flap lever failed. This plane was old and had suffered through a great deal of testing. Kelsey was able to get out, where as Virden could not, and Kelsey survived.
The truth about the wind tunnel was that NACA felt the speeds would wreck their wind tunnel. It could generate the speeds.
From Kelly Johnson's notes on the P-38 and compression:
At Mach .65, drag increases violently as a shock wave formed on the wing center section
At Mach .675 buffeting develops, and shortly after Mach tuck (diving tendency) begins. The tendnecy peaks at Mach .74.
For a number of reasons, it was virtually impossible to encounter compressibility tuck in any P-38 types if the dive was entered at 25,000 feet or less. Numerous flight tests by LeVier, Burcham, and Mattern confirmed that.
