The Boeing 787 is the new Boeing aircraft. It is currently in its development phase. Designers of this plane is made lot of research for this aircraft should be particularly fuel-efficient through the use of composite materials in the construction of the device and use of new reactors. The X-38 Crew Return Vehicle (CRV) was a prototype for a wingless lifting body reentry vehicle that was to be used as a Crew Return Vehicle for the International Space Station (ISS). The X-38 was developed to the point of a drop test vehicle before its development was cancelled in 2002 due to budget cuts. The X-43 is an unmanned experimental hypersonic aircraft with multiple planned scale variations meant to test various aspects of hypersonic flight. It was part of NASA's Hyper-X program. It has set several airspeed records for jet-propelled aircraft. The Lockheed Martin X-44 MANTA (Multi-Axis No-Tail Aircraft) was a conceptual aircraft design by Lockheed Martin that has been studied by NASA and the U.S. Air Force. The Boeing X-45 unmanned combat air vehicle is a concept demonstrator for a next generation of completely autonomous military aircraft, developed by Boeing's Phantom Works. The Boeing X-46 was a proposed unmanned combat air vehicle (UCAV) that was to be developed in conjunction with the U.S. Navy and DARPA as a naval carrier-based variant of the Boeing X-45 UCAV being developed for the U.S. Air Force. The Northrop Grumman X-47 is a demonstration Unmanned Combat Aerial Vehicle. The X-48 is an experimental unmanned aerial vehicle (UAV) for investigation into the characteristics of blended wing body (BWB) aircraft, a type of flying wing. The Boeing X-51 (also known as X-51 WaveRider) is an unmanned scramjet demonstration aircraft for hypersonic (Mach 6, approximately 4,000 miles per hour (6,400 km/h) at altitude) flight testing. It successfully completed its first free-flight on 26 May 2010 and also achieved the longest duration flight at speeds over Mach 5. The X-53 Active Aeroelastic Wing (AAW) development program is a completed research project that was undertaken jointly by the Air Force Research Laboratory (AFRL), Boeing Phantom Works and NASA's Dryden Flight Research Center, where the technology was flight tested on a modified McDonnell Douglas F/A-18 Hornet. The Gulfstream X-54 is a research and demonstration aircraft, under development in the United States by Gulfstream Aerospace, that is planned for use in sonic boom and supersonic transport research. The Lockheed Martin X-55 Advanced Composite Cargo Aircraft (ACCA) is an experimental twin jet engined transport aircraft. It is intended to demonstrate new cargo-carrier capabilities using advanced composites. A project of the United States Air Force's Air Force Research Laboratory, it was built by the international aerospace company Lockheed Martin, at its Advanced Development Programs (Skunk Works) facility in Palmdale, California. The Boeing Bird of Prey was a black project aircraft, intended to demonstrate stealth technology. The DARPA Falcon Project (Force Application and Launch from CONtinental United States) is a two-part joint project between the Defense Advanced Research Projects Agency (DARPA) and the United States Air Force (USAF) and is part of Prompt Global Strike. The Dassault nEUROn is an experimental Unmanned Combat Air Vehicle (UCAV) being developed with international cooperation, led by the French company Dassault Aviation. The Payen Pa 49 Katy was a small experimental French turbojet powered tailless aircraft, first flown in 1954, was the first French aircraft of this kind and the smallest jet aircraft of its day. MIT's D "double bubble" series design concept is based on a modified "tube-and-wing" structure that has a very wide fuselage to provide extra lift. The aircraft would be used for domestic flights to carry 180 passengers in a coach cabin roomier than that of a Boeing 737-800.