The F-19 fighter designation has been one of the recurring mysteries of the postwar era and is the subject of numerous posts to this newsgroup. Scarcely a week goes by in which at least one netter doesn't ask why there an apparent "hole" in the USAF fighter sequence between F-18 and F-20. Was F-19 never assigned to any fighter aircraft as the Air Force claims, or is it a cover for some supersecret "black" project that is yet to be revealed?
All throughout the late 1980s, it was sort of an open secret that the Air Force and the Lockheed "Skunk Works" were working on a project to develop a "stealth fighter" that would be invisible to radar. It was assumed by almost everyone that this project bore the designation F-19, since that designation had apparently been skipped when F-20 was assigned to a Northrop design. In July of 1986, the Testor Corporation of Rockford, Illinois released a $9.95 plastic kit model of what they called the "F-19 Stealth Fighter". Tom Clancy referred to a "F-19 Ghostrider" in his 1986 novel Red Storm Rising as part of a plot involving a future European war.
After years of gossip and rumors, on November 10, 1988, the existence of the Lockheed "stealth fighter" was finally officially revealed by the Defense Department. It turned out to be an attack aircraft rather than a fighter, since it apparently has no air-to-air capability. At the same time, it was also revealed that its designation was F-117. It seems that the F-117 designation has nothing to do with the old fighter sequence which ended at F-111, in spite of rumors that the Soviet fighters under test at Groom Lake conceal their real identity by using call-signs such as F-112, F-113, and so on. During its development and test phase, the Lockheed "stealth fighter" was known strictly under its project name of Senior Trend, and never carried any designation at all, certainly not a designation of F-19. Although the real origin of the F-117 designation is still not known with certainty, it seems to have been derived from the strict security restrictions that were in place at Groom Lake during the flight testing --- pilots flying the Senior Trend test aircraft were not allowed to tell anyone what type of aircraft they were flying, and so whenever asked to fill out routine forms that requested identification of the aircraft type they flew they would fill in the meaningless number 117. When the first manual for the Senior Trend aircraft appeared, it had F-117 printed on its cover. Since it would cost too much to have the manual reprinted, the designation later became official.
So it seems that the Lockheed Senior Trend was never known as F-19. So what then WAS F-19? When asked about this, an Air Force spokesman claimed that the F-19 designation had never been assigned to any aircraft because of a fear that it might be confused with the Soviet MiG-19. This doesn't seem plausible, because the designations F-17, F-21, and F-23 had not been skipped. Another theory claims that the designation F-19 had been skipped at the insistence of the Northrop Aircraft Corporation so that they could obtain the F-20 designation for their turbofan-powered derivative of the F-5 Tiger II fighter, which had initially been known as the F-5G. Presumably this would make for better advertising copy--"The Northrop F-20: First of a new generation of fighters", for example. A similar sort of thing happened during World War 2 when the designation P-74 (and perhaps P-73 as well) had been deliberately skipped at the request of the Fisher Body Division of General Motors who wanted their new heavy escort fighter to carry the designation P-75 for advertising reasons. However, I have been unable to come up with a primary source for the Northrop story, so at this stage I can regard it as little more than an "urban legend".
This still leaves the question of the missing F-19 unresolved. Perhaps it really is the designation of some other super-secret project, so black that it will not be revealed for many years. Maybe the mysterious "Aurora" that is the subject of so much gossip, rumor, and speculation in this group is designated F-19. However, it is still not at all certain that any such aircraft as the "Aurora" actually exists. Maybe it will turn out that the Air Force had been telling the truth all along, that there never was an aircraft known as F-19. Perhaps all of this confusion was part of a deliberate plot by the Air Force to confuse Soviet intelligence--hoodwinking them into expending so much effort in trying to find out information about a plane that does not exist.