Re: Seafire conversion of Spitfires in the 1940s
The fix was slightly more than a spring. Basically the problem was the pilot could apply more back stick than the aircraft could handle in certain situation leading to the nose pitching up too far/rapidly and the aircraft breaking up, due to the aft centre of gravity. It was so far aft they packed lead into the engine bearer and it was still on the limits of what would be acceptable for the land based variant.
To counter this a weight was hung off the front of the control column, this meant as the g-forces increased the pilot would have to apply increasing back pressure. Consequently pulling out of a dive the stick would actually be moving forwards despite the pilot maintaining a constant pressure.
The spring came into it to keep the control column in the neutral position. Unfortunately Supermarine mounted the weight horizontally off the front of the control column, so in a vertical dive it was hanging straight down and the pilot could still apply too much aft pressure before the g would act on the weight in the required direction. Leading to a loss of wings and the aircraft. The Fairey Firefly had a similar issue but the mount for the weight was at a 45 degree angle. And they didn't faff around with springs.
More on this, and other aspects of flying the most inappropriate naval aircraft of WW2, in the excellent 'They Gave Me a Seafire' by Mike Crosley.