Limit Load Factors WW2 Fighters eg. Spitfire, Mustang

[27/09]

Many a Spitfire broke up in mid air as a result of overly enthusiastic maneuvering. All the records, with rare exception, report the pilot being killed, so no hint on what he may have been doing when things came unstuck.

This made me go and lookup an incident Johnnie Houlton mentions in his book "Spitfire Strikes". This incident gives some idea what stress these aircraft could sustain and still bring their pilots home.

He had been testing out the supercharger aneroid control on a new Mk IX, and from 30,000 ft decide to do a Trim and Dive test on the way back down. He half rolled with 70% power and trimed into a vertical dive.

To quote;

"What followed next arose from a combination of 'finger trouble' and ignorance.....

.....when I started to pull out of the dive, the aircraft was flashing towards the earth at 1000 ft/sec. As I eased back on the stick and the elevator trim together, the nose of the Spitfire lifted about 20 degrees from the vertical, then the stick just "fell free" - I moved it quickly in all directions, and felt only 'snatching' here and there. Simultaneously the aircraft began to roll very slowly to the right, and I flicked on two quarter turns of nose-up trim on the trim-tab wheel....

.....The elevator sudddenly took over again and the Spitfire reared violently out of the dive, but the savage g force, forced my whole body downwards....... I was peering through a rain blurred window at a vague and wobbly image: "that's the instrument panel of a Spitfire . . . it's upside down . . . what am I doing in a Spitfire?" The panel flopped right side up, and I levered myself upright, to find the aircraft back at 9000 ft and still making sluggish upward rolls to the right. As I collapsed under the g force the split-type stick had folded across my right leg,. My goggles were over my mouth, my oxygen mask under my chin and I ached all over.....

.....The metal skin of the Spitfire wings were badly buckled and was 'oil canning' freely, and the wing tips were twisted....."

Imagine what stresses must have been applied to the aircraft that were lost through structural failure, though perhaps in some cases it could have been a culmination stress over a period of time.