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Boeing X-37 OTV (Orbital Test Vehicle)

2010 MODERN AIRCRAFT DRONE TECHNOLOGY

History of Boeing X-37 OTV (Orbital Test Vehicle)

The Boeing Defense X-37 is a long-term, reusable, unmanned spacecraft of the United States Air Force (USAF) and NASA that has performed multiple low- and high-profile round-trip low-Earth orbit (LEO) flights to date. The vehicle is classified as an "orbital test vehicle", hence the acronym "OTV" used in this publication.

The X-37 is now the smallest and lightest of all orbiting spacecraft (much smaller than NASA's original space shuttle fleet).

Boeing's work on the early X-40 glider undoubtedly influenced the design of the X-37 (the X-37 was slightly larger than the X-40). The X-37 was born from the original X-37A mold designed by NASA. The vehicle was handed over to DARPA under secret terms in 2004, and the Approach and Landing Test Vehicle (ALTV) grew out of earlier work and was eventually used for drop-glide testing in 2005 and 2006.

The X-37B marks the current (2017) operating model for the series, largely based on the X-37A modified to meet growing demand. Boeing's X-37C is also planned for an enlarged version, nearly 200 percent larger than the B model currently in use.

The X-37C will be used in conjunction with the Atlas V' Evolutionary One-shot Launch Vehicle (EELV), also in the planning stages.

Externally, the X-37B shares some visual similarities with previous STS space shuttles (aside from the traditional black and white color scheme). The nose is blunt, but suitable for atmospheric travel, but aerodynamically integrated into the aircraft's dorsal spine (since there is no need for a manned cockpit). The hull is almost plate-like, with a curved top and an almost flat bottom. Wing main planes are located low on the sides of the fuselage (as on the space shuttle) and amidships, with sweeps only found on the leading edge.

No horizontal fins were used - instead, the outwardly raked vertical fins served dual purpose in atmospheric flight. The landing gear is three-wheeled and fully retractable, with two-wheeled front legs and a single-wheeled main leg. These are used for traditional runways.

Inside, the vehicle is equipped with precise motorized nozzles in both the bow and stern areas. Avionics are located near the nose. The tail of the avionics is a kerosene-based JP-8 fuel tank, and the tail is a hydrogen peroxide tank (power is provided by gallium arsenide solar cells with lithium-ion batteries). The two fuel tanks are separated by a payload bay area that forms the central part of the fuselage.

The main engine is ejected through a nozzle at the rear of the spacecraft.

Vehicle dimensions include an overall length of 29.2 feet, a wingspan of 14.10 feet, and a height of 9.5 feet. Maximum takeoff weight (MTOW) is 11,000 lbs. Payload dimensions are 7ft x 4ft. Orbital speed (low Earth orbit) reaches 17,426 miles per hour.

The X-37 launch will be carried out using an Atlas V 501 series rocket (from United Launch Alliance), which has an enhanced Centaur rocket stage for extra propulsion on the go. The X-37 sits in the payload fairing prior to launch and is then released when it reaches the desired altitude. Landing is autonomous, and speeds approaching Mach 25 can be achieved in this maneuver.

The X-37 is the only space shuttle with this autonomous landing capability since the Soviet-era Blizzard. The process can be reused.

To date (2017), the X-37B has completed four major missions (flights from OTV-1 to OTV-4). OTV-1 launched on April 22, 2010 and flew the USA-212 mission lasting more than 224 days. On its return, it completed America's first autonomous runway landing. OTV-2 launched for Mission USA-226 on March 5, 2011, and remained in space for more than 468 days. The mission marked the maiden flight of the second X-37B.

OTV-3 was launched on December 11, 2012, and mission USA-240 lasted more than 674 days. This was the second flight of the first X-37B example. Launched for Mission USA-261 on May 20, 2015, OTV-4 has been in orbit for 717 days.

This was the X-37B's second flight and the first to land at the Space Shuttle Landing Facility at Kennedy Space Center in Florida.

To date (2017), two airworthy X-37B spacecraft have been completed. Their mission remains largely hidden from the public, so speculation abounds about its true purpose. Some believe the series is nothing more than a test vehicle to collect data on various components during missions.

Others see the series as consistent with the U.S. Air Force's dominance in space and its quest to stay ahead of the booming Chinese space program.