IMO improving the P-39 really centers around one of three things happening.
1) Sufficent turbo production to equip the P-39 with one. The plane was designed to use one and it never had the performance as a production model that the prototype did
2) Boost Merlin production at Packard enough to install in P-39s
3) The real wild card. The War Department gives Ford the go ahead to build the V-1650 which on paper looked to be as good and most likely better than the Merlin and cheaper to build too due to its replacing a lot of the expensive forgings with steel castings and the use of side by side rods instead of Fork and Blade. Ford was so confindent that the company ordered the tooling for production with out even getting a contract from the Air Corps. But all was not in vain as the engine with four cylinders removed became the GAA Tank Engine http://www.fordgaaengine.com/ One unusual feature of the XV-1650 was the studs on the Main Bearing Caps were splayed outwards at 30 degrees to vertical so that two studs carried the load for the right bank and two for the left bank.
A better wing would be an improvement but a new wing and some other stuff just gets you the P-63. It really centers around the powerplant.
Or better yet, Pratt and Whitney doesn't get cold feet and develops the x-1800 http://en.wikipedia.org/wiki/Pratt_%26_Whitney_X-1800 and Bell manages to shoehorn one into the airframe
1) Sufficent turbo production to equip the P-39 with one. The plane was designed to use one and it never had the performance as a production model that the prototype did
2) Boost Merlin production at Packard enough to install in P-39s
3) The real wild card. The War Department gives Ford the go ahead to build the V-1650 which on paper looked to be as good and most likely better than the Merlin and cheaper to build too due to its replacing a lot of the expensive forgings with steel castings and the use of side by side rods instead of Fork and Blade. Ford was so confindent that the company ordered the tooling for production with out even getting a contract from the Air Corps. But all was not in vain as the engine with four cylinders removed became the GAA Tank Engine http://www.fordgaaengine.com/ One unusual feature of the XV-1650 was the studs on the Main Bearing Caps were splayed outwards at 30 degrees to vertical so that two studs carried the load for the right bank and two for the left bank.
A better wing would be an improvement but a new wing and some other stuff just gets you the P-63. It really centers around the powerplant.
Or better yet, Pratt and Whitney doesn't get cold feet and develops the x-1800 http://en.wikipedia.org/wiki/Pratt_%26_Whitney_X-1800 and Bell manages to shoehorn one into the airframe
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