Shortround6
Major General
I suspect some, perhaps much, anti-P39 sentiment was due to prejudice.
Not to disregard actual relative performance deficiencies, but it just may be possible that some people were put off by what they considered an unusual, odd layout and different handling characteristics.......I imagine if the P-39 offered outstanding performance these prejudices would have been more easily overcome.
The British, who were the first to actually try to fly it in combat, felt that they had been deceived about it's actual performance. Put that together with trying to debug a new aircraft with a lot of problems and said aircraft doesn't really do anything that other available aircraft won't already do and it is not hard to figure out why they passed on the P-39.
Americans used bad tactics and persisted in overloading the plane. Add in the serviceability issues of the early models and the plane's lack of range, hard to go the offensive with it the Pacific or Europe from British bases, and one can see why the P-39 wasn't a favorite of the war planners.
Early American P-39s either had the 20mm, which may have had problems of it's own and only had a 60 rd drum, or had the 37mm, which in early versions had a defective ejection chute which caused numerous jams, usually after just a couple of shots. By the time the electrical system was sorted out and the armament issues resolved and the engines officially allowed to use WEP ratings, other fighters were becoming available in quantity for US forces.
P-39s in US service suffered from bad timing. Committed to combat with unresolved electrical/ mechanical issues, with insufficient support, using bad tactics and flown by mostly green pilots it is little wonder they failed to make a good impression.
While few in numbers how did the Free French and Italian pilots make out with them in 1943-44?