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Boeing X-37 OTV (Orbital Test Vehicle)

Unmanned Low Earth Orbit Space Vehicle

Boeing X-37 OTV (Orbital Test Vehicle)

Unmanned Low Earth Orbit Space Vehicle


The Boeing X-37 reusable unmanned orbiter has completed four missions to date involving the X-37B design.
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ORIGIN: United States
YEAR: 2010
STATUS: Active, In-Service
MANUFACTURER(S): Boeing Defense, Space & Security - USA
OPERATORS: United States
National flag of United States
Technical Specifications

Unless otherwise noted the presented statistics below pertain to the Boeing X-37B model. Common measurements, and their respective conversions, are shown when possible.
POWER: 1 x hydrogen peroxide-fueled main engine with JP-8 kerosene-based jet fuel tank; rocket-boosted to achieve low-earth orbit.







Variants / Models

• X-37 - Base Series Name
• X-37A - Initial vehicle developed by NASA; used in glide testing; later passed on to DARPA.
• X-37B - Modified X-37A for expanded mission set.
• X-37C - Proposed, dimensionally larger, variant of the X-47B with seating for up to six mission personnel.


Detailing the development and operational history of the Boeing X-37 OTV (Orbital Test Vehicle) Unmanned Low Earth Orbit Space Vehicle.  Entry last updated on 5/21/2018. Authored by Staff Writer. Content ©
The Boeing Defense X-37 serves the United States Air Force (USAF) and NASA as a reusable, long-duration, unmanned spacecraft and has, to date, completed several low- and high-profile flights to and from Low Earth Orbit (LEO). The craft is categorized as an 'Orbital Test Vehicle' and therefore takes on the acronym of 'OTV' in publication. The X-37 now stands as the dimensionally smallest and lightest of all of the orbital-minded spacecraft ever flown (it is decidedly smaller than the original NASA space shuttle fleet).

Boeing's work on the earlier X-40 glide vehicle no doubt influenced the design of the X-37 (the X-37 is slightly larger than the X-40). The X-37 was born through the X-37A form which was the initial design pushed by NASA. In 2004, the craft passed to DARPA under classified terms and the Approach and Landing Test Vehicle (ALTV) was derived from the earlier work, ultimately used for drop-glide testing during 2005 and 2006. The X-37B marks the current (2017) operational model of the series and is largely based on the X-37A with modifications made to suit growing requirements. A scaled-up version is also planned as the X-37C by Boeing, nearly 200% larger than the B-model currently in use. The X-37C will be mated to the Atlas V 'Evolved Expendable Launch Vehicle (EELV) also being planned.

Externally, the X-37B shares some visual similarities with previous STS space shuttle craft (beyond the traditional black-and-while color scheme). The nose is blunt yet aerodynamic for atmospheric travel and integrated into the dorsal spine of the vehicle (since no manned flight deck is needed). The fuselage is nearly-slab-sided with a curved top and near-flat bottom. The wing mainplanes are positioned low along the fuselage sides (as in the space shuttle) and at midships with sweep found along the leading edges only. No horizontal tailplanes are used - instead, outward-cranked vertical fins serve a dual purpose during atmospheric flight. The undercarriage is of a tricycle arrangement and fully-retractable with a double-wheeled nose leg and single-wheeled main legs. These are used for traditional runway landings.

Internally, the craft features precision maneuvering thrusters at both its nose and tail sections. Avionics are positioned near the nose. Aft of the avionics fit is the JP-8 kerosene-based fuel-tank and a hydrogen peroxide tank is positioned further aft (electrical power is by way of a Gallium arsenide solar cell-based unit with lithium-ion batteries). Separating the two tanks is the payload bay area making up the central portion of the fuselage. The main engine exhausts through a nozzle at the extreme rear of the spacecraft.

Boeing X-37 OTV (Orbital Test Vehicle) (Cont'd)

Unmanned Low Earth Orbit Space Vehicle

Boeing X-37 OTV (Orbital Test Vehicle) (Cont'd)

Unmanned Low Earth Orbit Space Vehicle

Dimensions of the vehicle include an overall length of 29.2 feet, a wingspan of 14.10 feet and a height of 9.5 feet. Maximum Take-Off Weight (MTOW) is 11,000lb. The payload measures 7 feet x 4 feet. Orbital speeds (Low Earth Orbit) reach 17,426 miles per hour.

Launching of the X-37 is accomplished by way of an Atlas V 501 series rocket (by United Launch Alliance) with a boosted 'Centaur' rocket stage adding additional propulsion during the voyage. The X-37 sits within a payload fairing prior to launch and is then released when the desired altitude is achieved. Landing is autonomous and speeds nearing Mach 25 are reached during this action. The X-37 is the only space plane, after the Soviet-era 'Buran' shuttle, to feature this autonomous landing capability. The craft is reusable.

To date (2017), there have been four major missions involving the X-37B (flights OTV-1 through OTV-4). OTV-1 was launched on April 22nd, 2010 and conducted mission USA-212 which lasted over 224 days. It completed the first American autonomous orbital runway landing upon its return. OTV-2 launched on March 5th, 2011 for mission USA-226 and remained in space for over 468 days. This mission marked the first-flight of the second X-37B example. OTV-3, launched on December 11th, 2012, went on mission USA-240 which lasted over 674 days. it marked the second flight of the first X-37B example. OTV-4 was launched on May 20th, 2015 for mission USA-261 and marked over 717 total days in orbit. This was the second flight of X-37B and the first flight to land at the Shuttle Landing Facility of Kennedy Space Center in Florida.

Two flyable X-37B spacecraft have been completed to date (2017). Their missions remain largely secretive to the public so speculation abounds as to their true purpose. Some view the series as nothing more than test vehicles collecting data on different components during missions. Others suspect the series to be in line with USAF dominance of space - attempting to remain steps ahead of a rising Chinese space program.


Our Data Modules allow for quick visual reference when comparing a single entry against contemporary designs. Areas covered include general ratings, speed assessments, and relative ranges based on distances between major cities.

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Relative Maximum Speed
Hi: 20000mph
Lo: 10000mph
This entry's maximum listed speed (10,827mph).

Graph average of 15000 miles-per-hour.
Aviation Era
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Unit Production (2)
Comm. Market HI*: 44,000 units
Military Market HI**: 36,183 units

  * Commercial Market High belongs to Cessna 172.

  ** Military Market High belongs to Ilyushin Il-2.

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Supported Roles
Ground Attack
Aerial Tanker
A2A=Air-to-Air; UAV=Unmanned; CAS=Close Support; ASW=Anti-Submarine; AEW=Airborne Early Warning; MEDEVAC=Medical Evac; EW=Electronic Warfare; SAR=Search-Rescue
Commitments / Honors
Military lapel ribbon for Operation Allied Force
Military lapel ribbon for the Arab-Israeli War
Military lapel ribbon for the Battle of Britain
Military lapel ribbon for the Battle of Midway
Military lapel ribbon for the Berlin Airlift
Military lapel ribbon for the Chaco War
Military lapel ribbon for the Cold War
Military lapel ribbon for the Cuban Missile Crisis
Military lapel ribbon for pioneering aircraft
Military lapel ribbon for the Falklands War
Military lapel ribbon for the French-Indochina War
Military lapel ribbon for the Golden Age of Flight
Military lapel ribbon for the 1991 Gulf War
Military lapel ribbon for the Indo-Pak Wars
Military lapel ribbon for the Iran-Iraq War
Military lapel ribbon for the Korean War
Military lapel ribbon for the 1982 Lebanon War
Military lapel ribbon for the Malayan Emergency
Military lapel ribbon representing modern aircraft
Military lapel ribbon for the attack on Pearl Harbor
Military lapel ribbon for the Six Day War
Military lapel ribbon for the Soviet-Afghan War
Military lapel ribbon for the Spanish Civil War
Military lapel ribbon for the Suez Crisis
Military lapel ribbon for the Vietnam War
Military lapel ribbon for Warsaw Pact of the Cold War-era
Military lapel ribbon for the WASP (WW2)
Military lapel ribbon for the World War 1
Military lapel ribbon for the World War 2
Military lapel ribbon for the Yom Kippur War
Military lapel ribbon for experimental x-plane aircraft
* Ribbons not necessarily indicative of actual historical campaign ribbons. Ribbons are clickable to their respective campaigns/operations.

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