What does 51 stand for in p-51 mustang?

Answer:
51 stands for the model of the Plane. The P stands for the series of planes example: P-40
P-47
P-38
P-51
The number i dentifies the specific plane. Planes are also updated or improved, so they put in letters example: P-51 B, P-51 D, P-51 H, ect.
First answer by Deerhunter74. Last edit by Deerhunter74. Contributor trust: 2 [recommend contributor recommended]. Question popularity: 1 [recommend question].