Between 1940 and 1946, Henshaw flew a total of 2,360 Spitfires and Seafires, more than 10% of total production.[98][99]
Henshaw wrote about flight testing Spitfires:
After a thorough pre-flight check I would take off and, once at circuit height, I would trim the aircraft and try to get her to fly straight and level with hands off the stick ... Once the trim was satisfactory I would take the Spitfire up in a full-throttle climb at 2,850 rpm to the rated altitude of one or both supercharger blowers. Then I would make a careful check of the power output from the engine, calibrated for height and temperature ... If all appeared satisfactory I would then put her into a dive at full power and 3,000 rpm, and trim her to fly hands and feet off at 460 mph IAS (Indicated Air Speed). Personally, I never cleared a Spitfire unless I had carried out a few aerobatic tests to determine how good or bad she was. The production test was usually quite a brisk affair: the initial circuit lasted less than ten minutes and the main flight took between twenty and thirty minutes. Then the aircraft received a final once-over by our ground mechanics, any faults were rectified and the Spitfire was ready for collection. I loved the Spitfire in all of her many versions. But I have to admit that the later marks, although they were faster than the earlier ones, were also much heavier and so did not handle so well. You did not have such positive control over them. One test of manoeuvrability was to throw her into a flick-roll and see how many times she rolled. With the Mark II or the Mark V one got two-and-a-half flick-rolls but the Mark IX was heavier and you got only one-and-a-half. With the later and still heavier versions, one got even less. The essence of aircraft design is compromise, and an improvement at one end of the performance envelope is rarely achieved without a deterioration somewhere else.[100][101]
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