The U.S. Air Force has released new images of its experimental new X-37B space plane as the secretive mission's launch date next April draws near.

The X-37B, or OTV, spacecraft is pictured in launch configuration at a Boeing Co. factory in August 2009. Credit: U.S. Air Force

In a response to written questions, an Air Force spokesperson said the unmanned spaceship is scheduled for launch April 19 on an Atlas 5 rocket from Cape Canaveral, Fla.

The winged X-37B, also named the Orbital Test Vehicle, is managed by the Air Force Rapid Capabilities Office under the direct supervision of the secretary of the Air Force and the undersecretary of defense for acquisition, technology, and logistics.

The photos were published by Air & Space Magazine and provided to Spaceflight Now by the Air Force.

Air Force officials declined earlier requests for interviews on the mission.

"The Air Force Rapid Capabilities Office expedites development and fielding of select Department of Defense combat support and weapon systems by leveraging defense-wide technology development efforts and existing operational capabilities," the unit's mission statement says.

The spacecraft measures more than 29 feet long and nine-and-a-half feet tall. Its wingspan is 14 feet, 11 inches, and it will weigh about 11,000 pounds at launch, according to an Air Force fact sheet.

The OTV will be shrouded inside a bulbous five-meter diameter payload fairing for launch. The Atlas 5 rocket will fly in the 501 configuration with the large nose cone, no solid rocket boosters and a single engine Centaur upper stage.

The X-37B Orbital Test Vehicle on the runway at Vandenberg Air Force Base for range and taxi tests in October 2007. A series of captive and released taxi tests were performed to gather data and refine models used by the X-37B during autonomous landing. Credit: U.S. Air Force

The military is tight-lipped on the demonstrator's payload for the April mission, but the Air Force says it will test space technologies and prove concepts for small reusable spacecraft.

The OTV spacecraft is currently awaiting launch at its factory at Boeing Phantom Works in California. The vehicle is integrated and ready for shipment to Cape Canaveral two months before launch, according to Andrew Bourland, a spokesperson for the secretary of the Air Force.

Officials say the biggest challenge of late has been securing a launch opportunity on the Eastern Range. One more Atlas 5 rocket is in the queue ahead of the OTV mission.

"There are no spacecraft threats to the schedule," Bourland said.

The Air Force has also not disclosed the length of the OTV's mission in space. The ship will glide to an autonomous re-entry and landing at the end of its flight, most likely at a lengthy runway modified for the space shuttle at Vandenberg Air Force Base, Calif.

The spacecraft completed a series of captive carry and free flight tests in 2006 underneath the privately-owned White Knight aircraft from Scaled Composites. Taxi tests were conducted at Vandenberg in 2007.