Years, not months. P-51 probably had the shortest development time. Prototype NA-73X flew in 1940. Early Allison powered A-36 and Mustang I entered service with RAF in 1942. The mature weapon system P-51B entered service in the winter of 1943-1944. F-35 prototype first flew in 2006.
Few things...
It shouldn't take a great deal of time to develop an aircraft, take a look on some of best selling aircraft around:
- A-4 Skyhawk, first flight 1954, introduction 1956 - 2 years
- MiG-21 - first flight 1956, in service 1959 - 3 years
- Mirage III - first flight 1956, introduction 1961 - 5 years
- F-4 Phantom, first flight 1958, introduction 1960 - 2 years
- F-15 - first flight 1972, introduction 1976 - 4 years
- F-16 - first flight for YF-16 1973, introduction 1978 - 5 years
- MiG-29 - first flight 1977, introduction 1983 - 6 years
Some Most Revolutionary designs:
- Harrier - Hawker Siddeley P.1127 1960, Harrier in serice 1969 - 9 years - first ever operation STOVL aircraft!!!
- Have Blue first flight 1977, F-117 in service 1983 - 5 years first ever stealth bomber.
At this point I wanted to "trash" the F-35 (F-35B: 2006 - 2015 - 9 years, F-35A - 2016 - 10 years and F-35C 2018 -12 years planned)
However I realized that F-35 isn't outstanding, if I take delay from first flight to introduction of
latest airframes:
Gripen 1988 - 1997 9 years
Rafale 1986 - 2001 15 years
Typhoon 1994 - 2003 9 years
Raptor 1997 - 2005 8 years
It looks like modern industry "unlearned" how to develop an aircraft. Today you have all CAD/CAM technologies, digital simulations you couldn't dread of in 60th and yet it takes 2-3 more times to produce an aircraft.
Horrible!