THE SECRET AND EXPERIMENTAL MILITARY AIRCRAFT OF THE PAST AND PRESENT

Let’s start this story off with the fastest aircraft ever developed by the American military. The Falcon Hypersonic Test Vehicle 2 is an experimental rocket glider piloted by remote control that is designed to push the envelope of faster-than-sound travel to the tune of Mach 22. The idea is to create a craft that can reach any target in the world and deliver an explosive strike within a single hour, and to do so DARPA has developed a tough, lightweight glider.
read more: http://www.tested.com/tech/454420-secret-and-experimental-military-planes-around-world/item/falcon-hypersonic-test-vehicle-2/#gallery?icid=maing-grid7%7Cnetscape%7Cdl8%7Csec1_lnk3%26pLid%3D295126

The Air Force has definitely demonstrated a need for speed, and no experimental plane quenched that thirst quite like the X-51. Boeing’s X-51 Waverider, produced in conjunction with Pratt & Whitney Rocketdyne, was built to exceed Mach 6 – far faster than any current military aircraft. It’s launched into the atmosphere by a B-52 and uses its hydrocarbon-fueled scramjet engine to accelerate to hypersonic speeds. The final test flight for the Waverider is set to happen later this year.

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 powered flight on 26 May 2010 and also achieved the longest duration flight at speeds over Mach 5.[1]

The X-51 is named "WaveRider" because it uses its shockwaves to add lift. The program is run as a cooperative effort of the United States Air Force, DARPA, NASA, Boeing, and Pratt & Whitney Rocketdyne. The program is managed by the Propulsion Directorate within the United States Air Force Research Laboratory (AFRL).[3] The X-51 had its first captive flight attached to a B-52 in December 2009

You can’t go anywhere these days without hearing about drones, but the concept of unmanned planes waging war isn’t a new one. Lockheed-Martin pioneered the concept in the 1990s with a project code-named DarkStar. This was a top secret development mission to produce an unmanned reconnaissance drone with stealth capabilities, and even though the project was terminated in 1998 rumors circulated that it was brought back as an undercover “black ops” protocol and used during the 2003 invasion of Iraq.

The RQ-3 DarkStar was designed as a "high-altitude endurance UAV", and incorporated stealth technology to make it difficult to detect, which allowed it to operate within heavily defended airspace, unlike the RQ-4 Global Hawk, which is unable to operate except under conditions of air superiority. The DarkStar was fully autonomous: it could take off, fly to its target, operate its sensors, transmit information, return and land without human intervention. Human operators, however, could change the DarkStar's flight plan and sensor orientation through radio or satellite relay. The RQ-3 carried either an optical sensor or radar, and could send digital information to a satellite while still in flight. It used a single jet engine of unknown type for propulsion. http://en.wikipedia.org/wiki/RQ-3_DarkStar

The first prototype made its first flight on March 29, 1996, but its second flight, on April 22, 1996, ended in a crash shortly after takeoff. A modified, more stable design (the RQ-3A) first flew on June 29, 1998, and made a total of five flights before the program was canceled just prior to the sixth and final flight planned for the airworthiness test phase. Two additional RQ-3As were built, but never made any flights before program cancellation.
Although purportedly terminated on January 28, 1999, it was reported in April 2003 that the RQ-3 was still in development as a black project.[2] The size and capabilities were reported to have increased somewhat. It was further alleged that the first such example had been used in the 2003 invasion of Iraq.[2] There has been no independent confirmation.

The "R" is the Department of Defense designation for reconnaissance; "Q" means unmanned aircraft system. The "3" refers to it being the third of a series of purpose-built unmanned reconnaissance aircraft systems.