Changes

===Merlin engine===

===Merlin engine===

In 1942 the British experimented by replacing the Allison with their own more powerful liquid-cooled Rolls-Royce Merlin supercharged engine; the P-51 suddenly became the fastest piston- engine plane of all time. While it took a great deal of training to handle this "hot" plane properly, it could outperform anything but a jet. The new P-51B and P-51C models could fly 453 mph at 28,800 feet (versus 250 mph that high with the old Allison engines) and could climb to 20,000 feet in 6 minutes instead of 11. Washington now ordered all-out production. With Packard Corporation making the Merlin engine under license, the P-51B started rolling off North American's assembly lines in Los Angeles and Dallas in June, 1943.  

In 1942 the British experimented by replacing the Allison with their own more powerful liquid-cooled Rolls-Royce Merlin supercharged engine; the P-51 suddenly became the fastest single-engined fighter of the time. While it took a great deal of training to handle this "hot" plane properly, it could outperform anything but a jet. The new P-51B and P-51C models could fly 453 mph at 28,800 feet (versus 250 mph that high with the old Allison engines) and could climb to 20,000 feet in 6 minutes instead of 11. Washington now ordered all-out production. With Packard Corporation making the Merlin engine under license, the P-51B started rolling off North American's assembly lines in Los Angeles and Dallas in June, 1943.

==Escort role==

==Escort role==