Shortround6
Major General
To replace the Hurricane you need a plane that you could have 2000 of by the end of July 1940. The American aircraft industry, large as it was in 1939-40, was a mere infant compared to what it would become. It really wasn't in a position to supply 2000 fighters from the summer of 1938 to the summer of 1940 of any type let alone planes that flew as prototypes in 1939.
The Hawk 75 was as good as it was going to get as far as what was available and while the problems could have been fixed ( and were in the P-40 which used the same basic airframe from the firewall back) there is no reason for British factories to sit idle while american planes are purchased. American planes were purchased because Britihs production was already maxed out for the time( new factories were under construction but time was needed as was equipment for the factories and time was needed to train workers)
The Hawk 75 was as good as it was going to get as far as what was available and while the problems could have been fixed ( and were in the P-40 which used the same basic airframe from the firewall back) there is no reason for British factories to sit idle while american planes are purchased. American planes were purchased because Britihs production was already maxed out for the time( new factories were under construction but time was needed as was equipment for the factories and time was needed to train workers)