Welcome to the world's best military aircraft museum, hosted by none other than Uncle Sam himself. Tucked deep in the bowels of one of America's less interesting states (sorry, Ohio!), this facility has more floorspace than any other of the museums I've visited, and historically important aircraft to fill all of it and then some, with quite a few planes parked outside together with a gaggle of the missiles which made the Cold War such a fun time.
Naturally enough the focus is on historically significant aircraft of the United States Air Force, ranging from slightly pre World War Two through to the modern day, represented by a YF-22 Raptor. World War Two bombers include the B-18 Bolo, B-24 Liberator and B-25 Mitchell; suprisingly, at the time I visited there was no example of the most famous American bomber of the war, the B-17 Flying Fortress, and the B-29 Superfortress was represented only by a cutaway fuselage and the very modified tanker version, the KC-97 Stratofreighter. World War Two fighters include the P-47 Thunderbolt and P-39 Aerocobra.
There are also aircraft from countries which fought against the US Air Force. World War Two German aircraft are represented by a Bf109, FW190, Me262 jet, Fieseler Storch and V1 and V2 rockets, the Italians by a Macchi Saetta, and the Japanese by a Kawanishi "George" and an Ohka rocket-powered kamikaze plane. Unfortunately, neither of the Japanese aircraft was on display, though if you're desperate then you can look at this photo of an Ohka at Quantico marine museum.
Finally, there's a very interesting section of weird and wonderful USAF aircraft, most of which never got out of the developmental stage. However, the first of these, the F-82 "Twin Mustang", did go into production and was used for some time, achieving some success during the Korean War. As its name suggests, and despite protestations to the contrary on its plaque, the Twin Mustang consists of two P-51 Mustangs joined together at the wing and tail. The comically stubby XF-85 Goblin is next, a "parasitic" jet fighter designed to be carried by the enormous B-36 Peacemaker bomber, and released to ward away enemy fighters before being recaptured and pulled back on board its mother plane. The Ryan X-13 Vertijet is another product of this period, designed to take off and land vertically from a mobile stand. The "Tacit Blue" is a much more recent test aircraft, designed as a test bed for the stealth concepts which were soon incorporated into the F-117 Knighthawk "stealth fighter" and B-2 Spirit "stealth bomber". Another aircraft built to explore radical technologies is the Grumman X-29, a modern looking jet with wings swept forward instead of backwards.