$139.95 Buy Now	"XP-55 Ascender" "The XP-55 (Curtiss Model 249C), along with the XP-54 and XP-56, resulted from Army Air Corps proposal R-40C calling for unconventional aircraft designs. Like the XP-54, the Ascender was initially designed for the Pratt & Whitney X-1800 engine and had to be redesigned when the engine project was canceled. The XP-55 first flew on 13 July 1943 with an Allison V-1710 engine. The aircraft experienced stability problems and had modifications to increase the canard elevator surface, vertical stabilizer area, and eventually received wing tip extensions."

$109.95 Buy Now	"X-1 as used by Chuck Yeager to Break the Sound Barrier" "The Bell X-1 took its place in history on October 14, 1947 as the first aircraft to break the ""sound barrier"". The recorded speed was Mach 1.015 or 670 mph at an altitude of 42,000 ft. The ""plane"" was flown by chief test-pilot Chuck Yeager."

$134.95 Buy Now	"XB-70 Valkyrie" "The XB-70 Valkyrie was designed in the early 1960s at a cost of more than $5 billion. It was to be the replacement for the B-52, by then out of production, as America's strategic bomber. The program was cancelled as the flight testing was underway."

$170.00 Buy Now	"X-1 Glamorous Glennis, Aluminum Aircraft Panel" "The Bell X-1 took its place in history on October 14, 1947 as the first aircraft to break the ""sound barrier"". The recorded speed was Mach 1.015 or 670 mph at an altitude of 42,000 ft. The ""plane"" was flown by chief test-pilot Chuck Yeager."

$199.95 Buy Now	"X-45A UCAV" "Developed by Boeing to prove the value of unmanned aircraft in dangerous, high-priority combat roles, the X-45A UCAV would, in typical missions, be pre-programmed with objectives and target information from ground-based mission planners. It could then carry out operations on its own, or receive new command input enroute from controllers using satellite and line-of-sight communication links."

$139.95 Buy Now	"XP-59 Aerocomet" "The Airacomet was America's first jet-propelled airplane. Developed during World War II, it was such a top secret project that hundreds of flights had already been been made before it was announced to the public in 1943. Bell produced 66 P-59s. Although the airplane's performance was not spectacular and it never got into combat, the P-59 provided training for AAF personnel and invaluable data for subsequent development of higher performance jet airplanes."

$134.95 Buy Now	"XF-85 ""Goblin""" "The XF-85 parasite aircraft was developed to protect B-36 bombers flying beyond the range of conventional escort fighters. In theory, a B-36 penetrating enemy territory would carry its protecting fighter in the bomb bay. If attacked by enemy aircraft, the bomber would lower the Goblin on a trapeze and release it to combat the attackers."

$129.95 Buy Now	"X-3 Stiletto Experimental Aircraft" "The X-3 made its first flight on September 20, 1952. The X-3 made its first flight at Edwards AFB on October 20, 1952, with Douglas pilot Bill Bridgeman in the cockpit. The X-3 was powered by two afterburning 4,850lb thrust Westinghouse J34-WE-17 turbojet engines, although it was planned to have two afterburning 7,000lb thrust Westinghouse J46-WE-1 turbojets. Because the aircraft was severely underpowered, the aircraft could barely reach supersonic speeds unless it dove from a high altitude. The aircraft was retired after only 51 total flights."

$129.95 Buy Now	"X-4 Bantam Experimental Aircraft" "The Northrop X-4 Bantam was a small twin-jet airplane that had no horizontal tail surfaces, depending instead on combined elevator and aileron control surfaces (called elevons) for control in pitch and roll attitudes. The hope of some aerodynamicists was that eliminating the horizontal tail would also do away with stability problems at transonic speeds resulting from the interaction of supersonic shock waves from the wings and the horizontal stabilizers."

$129.95 Buy Now	"X-47 Pegasus UCAV" "Northrop Grumman built the X-47/Pegasus unmanned combat aerial vehicle (UCAV) demonstrator under a $12 million DARPA/Navy contract. It is intended to evaluate technologies and concepts for a possible follow-on carrier-capable, naval UCAV (UCAV-N) for fielding in the post-2010 timeframe. The UCAV-N is to perform three missions: surveillance, strike, and suppression of enemy air defenses (SEAD). The single X-47 flight test aircraft was formally rolled out in July, 2001."

$134.95 Buy Now	"X-33 (SSTO) Single Stage To Orbit Space Shuttle" "SSTO Next Phase -- ""X-33"" Given the success of the DC-X1, and the potential for a new generation of low-cost, reliable space launch vehicles, an ""advanced technology demonstrator"" (""ATD"") ""X""-vehicle SSTO demonstrator is the prudent next step. The most cost effective approach is a follow-on program to build, and preferably fly, an ATD, dubbed ""X-33."" This could be accomplished within four years following a competitive detailed system design phase."