drgondog
Major
I certainly agree that Curtiss was not involved in the design of the P-51. The question is are the similarities in the radiator design an example of convergent evolution or do the designs share the same roots (ie NACA).
The evolution in research papers were 1.) Meredith, 2.) Capon and 3.) Gothert (as translated by NACA). The major collaboration between NACA and NAA was developing wind tunnel test conditions too model non-operational configurations to investigate flow properties on the 1/4 scale model - using various size baffle plates to simulate the radiator internally - then much more when the full scale XP-51B was sent to Ames to investigate 'the Rumble' March/April 1943.
The key differentiator was the plenum design, the intake scoop and the variable geometry exit gate to accommodate high speed jet effect (closed-low drag) while also serving low speed/climb cooling (open-high drag).
Curtiss never figured out the upper lip/gutter effect to strip low energy BL from the intake plenum and radiator, nor did they figure out that the exhaust plenum needed length and variable geometry exit (Ditto Spit, all Bf 109 through E, Hurricane, etc.). It also took NAA two years to finally design an enduring cooling system that made major strides in reducing high speed cooling drag