The United States
military, since their first use of airplanes have given most of their fighter craft the designation of F. The F4F Corsair
, for example. There were many notable exceptions during World War II
, such as the venerable P-51
, or the P-47
. However, when jet designs began to replace propeller driven aircraft, the military wanted to consolidate their naming scheme under a single 'F', to begin with a clean slate. The McDonnell XFD-1 Phantom, the McDonnell XF2D-1 Banshee, and the North American XFJ-1 Fury, were all later designated as F-1, F-2, and F-3 respectively.
The 'New F' series of fighters has since proceeded largely unbroken. If that's the case, then why do we only hear about F-15 Eagles, F-16 Falcons, F-18 Hornets, and F-22 Raptors?
The biggest reason for the 'skipping' of numbers in the new F series, is the fact that most of them are actually only experimental designs. Two companies build prototypes for their prospective buyer (usually the United States Navy or Air Force). The two jets compete, and the Department of Defense selects one of them to purchase. Experimental models are proceeded by a Y, so that there is no actual F-17, but there was a YF-17, which competed with the YF-16 (which later became the F-16).
There are two examples that are not covered by experimental models, however.
There is not an actual F-13 fighter jet. The main reason for this was the common superstition with the number thirteen (hey, pilots are a superstitious bunch). So, in the interests of morale, the F-13 was skipped over.
There was an aircraft designated F-13, however. B-29 Superfortresses that were refitted for aerial surveillance and photography had the designation F-13, but they were most definitely not part of the new F series of jet fighters.
The only other F-number that does not have either a fighter, or an experimental prototype is the F-19.
The official line from the United States Air Force is that there simply was never any fighter given the designation F-19. After the F-20 designation was given to the Tigershark, rumor began to attach the F-19 to the semi-secret 'stealth fighter' project that was underway at Lockheed's Skunk Works division. Public culture began to fill the void of the F-19's absence. The computer game maker Microprose released an F-19 Stealth Fighter game for the 286. In 1986, the Testor Corporation of Illinois released a ten buck plastic kit model of a so-called "F-19 Stealth Fighter". Also in 1986, master of acronyms Tom Clancy referred to an "F-19 Ghostrider" in his novel Red Storm Rising.
The stealth fighter theory crumbled, however, when it was revealed that the 'stealth fighter' was not actually a fighter, but an attack aircraft. The F-117 Nighthawk, which is the all-black, angular, UFO-ish plane that was so successful in the Gulf War.
The Air Force later stated that the F-19 was skipped so that it would not be confused with the Soviet Union's MiG-19 jet fighter. This statement does not hold up as well, since neither the F-17, F-21, nor the F-23 had been similarly skipped (they all share a MiG counterpart model). Another theory suggests that the skip may have been for marketing purposes. This may have been to give the makers of the F-20 Tigershark a more 'new' image, instead of the old, out-of-date, and un-sexy connotations of a jet fighter designated F-19.
Other theories include:
The F-19 belongs to some unknown ultra-secret project that may or may not be underway any longer
The mysterious and much rumored, although unconfirmed 'Aurora' is actually the F-19
A plot on the part of the US military to confuse Soviet intelligence, making them think that there actually was a secret project when there really wasn't, making them waste resources chasing a wild goose
The powers that be goofed on a form somewhere, accidently skipping the F-19
Maybe the Air Force was really just telling the truth
For more information, check out Joe Baugher's Encylcopedia of American Military Aircraft