Stability and Control characteristics of the Early Mark Spitfires

[DC338]

It was not until the design was evaluated under a set of measured and defined standards that the longitudinal instability was quantified and fixed in the Spitfire.

Can you explain this further. Fixed As a result of NACA? How? Surely not.

Can we have a analysis of figures 16 17 & 18 pointing to the instability in these test? It would appear tha 15 is an anomaly when compared to the later test.