Unmanned aerial vehicle

A group photo of aerial demonstrators at the 2005 Naval Unmanned Aerial Vehicle Air Demo.

An unmanned aerial vehicle (UAV; also known as a remotely piloted vehicle or RPV, or Unmanned Aircraft System (UAS)) is an aircraft that flies without a human crew on board the aircraft. Their largest uses are in military applications. To distinguish UAVs from missiles, a UAV is defined as a reusable, uncrewed vehicle capable of controlled, sustained, level flight and powered by a jet or reciprocating engine. Therefore, cruise missiles are not considered UAVs, because, like many other guided missiles, the vehicle itself is a weapon that is not reused, even though it is also unmanned and in some cases remotely guided.

There are a wide variety of UAV shapes, sizes, configurations, and characteristics. Historically, UAVs were simple drones[1] (remotely piloted aircraft), but autonomous control is increasingly being employed in UAVs. UAVs come in two varieties: some are controlled from a remote location, and others fly autonomously based on pre-programmed flight plans using more complex dynamic automation systems.

Currently, military UAVs perform reconnaissance as well as attack missions.[2] While many successful drone attacks on militants have been reported, they are also prone to collateral damage and/or erroneous targeting, as with many other weapon types.[1] UAVs are also used in a small but growing number of civil applications, such as firefighting or nonmilitary security work, such as surveillance of pipelines. UAVs are often preferred for missions that are too "dull, dirty, or dangerous" for manned aircraft.

The abbreviation UAV has been expanded in some cases to UAVS (unmanned-aircraft vehicle system). In the United States, the Federal Aviation Administration has adopted the generic class unmanned aircraft system (UAS) originally introduced by the U.S. Navy to reflect the fact that these are not just aircraft, but systems, including ground stations and other elements.

Contents

History

Ryan Firebee was a series of target drones/unmanned aerial vehicles.

The earliest unmanned aerial vehicle was A. M. Low's "Aerial Target" of 1916.[3] A number of remote-controlled airplane advances followed, including the Hewitt-Sperry Automatic Airplane, during and after World War I, including the first scale RPV (Remote Piloted Vehicle), developed by the film star and model airplane enthusiast Reginald Denny in 1935.[3] More were made in the technology rush during the Second World War; these were used both to train antiaircraft gunners and to fly attack missions. Jet engines were applied after WW2, in such types as the Teledyne Ryan Firebee I of 1951, while companies like Beechcraft also got in the game with their Model 1001 for the United States Navy in 1955.[3] Nevertheless, they were little more than remote-controlled airplanes until the Vietnam Era.

The birth of US UAVs (called RPVs at the time) began in 1959 when USAF officers, concerned about losing US pilots over hostile territory, began planning for the use of unmanned flights.[4] This plan became intensified when Francis Gary Powers and his "secret" U2 were shot down over the USSR in 1960. Within days, the highly classified UAV program was launched under the code name of "Red Wagon." [5] During the Vietnam War, the 02 and 04 August 1964 clash in the Tonkin Gulf between naval units of the US and North Vietnamese Navy initiated America's highly classified UAVs into their first combat missions of the Vietnam War. [6] Indeed, the USAF's UAVs were so secret, than even when the "Red Chinese"[7] showed photographs of downed US UAVs via Wide World Photos[8], the official US response was, "no comment." Only on February 26, 1973, during testimony before the US House Appropriations Committe, did the US military officially confirm that they had been utilizing UAVs in Southeast Asia (Vietnam).[9] While over 5,000 US airmen had been killed and over 1,000 more were either missing in action (MIA), or captured (prisoners of war/POW); the USAF 100th Strategic Reconnaissance Wing had flown approximately 3,435 UAV missions during the war,[10] at a cost of about 554 UAVs lost to all causes. In the words of USAF General George S. Brown, Commander, Air Force Systems Command in 1972, "The only reason we need (UAVs) is that we don't want to needlessly expend the man in the cockpit..."[11] Later that same year, General John C. Meyer, Commander in Chief, SAC command, stated, "...we let the drone do the high risk flying...the loss rate is high, but we are willing to risk more of them...they save lives!"[12]

During the 1973 Yom Kippur War, Syrian missile batteries in Lebanon caused heavy damages to Israeli fighter jets. As a result, Israel developed their first modern UAV. The images provided by these UAVs helped Israel to completely neutralize the Syrian air defenses at the start of the 1982 Lebanon War, resulting in no pilots downed.[13]

With the maturing and miniaturization of applicable technologies as seen in the 1980s and 1990s, interest in UAVs grew within the higher echelons of the US military. UAVs were seen to offer the possibility of cheaper, more capable fighting machines that could be used without risk to aircrews. Initial generations were primarily surveillance aircraft, but some were armed (such as the MQ-1 Predator, which utilized AGM-114 Hellfire air-to-ground missiles). An armed UAV is known as an unmanned combat air vehicle (UCAV).

As a tool for search and rescue, UAVs can help find humans lost in the wilderness, trapped in collapsed buildings, or adrift at sea.

UAV classification

Although most UAVs are fixed-wing aircraft, rotorcraft designs such as this MQ-8B Fire Scout are also used.
Schiebel S-100 fitted with a Lightweight Multirole Missile

UAVs typically fall into one of six functional categories (although multi-role airframe platforms are becoming more prevalent):

They can also be categorised in terms of range/altitude and the following has been advanced as relevant at such industry events as ParcAberporth Unmanned Systems forum:

Additional category can be applied in pattern of function: fixed routes vs. dynamically variable routes:

The United States military employs a tier system for categorizing its UAVs.

United States military UAV classifications

The modern concept of U.S. military UAVs is to have the various aircraft systems work together in support of personnel on the ground. The integration scheme is described in terms of a "Tier" system, and is used by military planners to designate the various individual aircraft elements in an overall usage plan for integrated operations. The Tiers do not refer to specific models of aircraft, but rather roles for which various models and their manufacturers competed. The U.S. Air Force and the U.S. Marine Corps each has its own tier system, and the two systems are themselves not integrated.

US Air Force tiers

A MQ-9 Reaper, a hunter-killer surveillance UAV.

US Marine Corps tiers

U.S. Army tiers

Future Combat Systems (FCS) (U.S. Army) classes

Unmanned aircraft system

UAS, or unmanned aircraft system, is the official U.S. Department of Defense term for an unmanned aerial vehicle. Initially coined by the Navy to reflect the fact that these complex systems include ground stations and other elements besides the actual aircraft, the term was first officially used in the DoD 2005 Unmanned Aircraft System Roadmap 2005–2030.[21] Many people have mistakenly used the term Unmanned Aerial System, or Unmanned Air Vehicle System, as these designations were in provisional use at one time or another. The official acronym 'UAS' is not widely used outside military circles, however, as the term UAV has become part of the modern lexicon.

Predator launching a Hellfire missile

The military role of unmanned aircraft systems is growing at unprecedented rates. In 2005, tactical- and theater-level unmanned aircraft alone had flown over 100,000 flight hours in support of Operation Enduring Freedom and Operation Iraqi Freedom, in which they are organized under Task Force Liberty in Afghanistan and Task Force ODIN in Iraq. Rapid advances in technology are enabling more and more capability to be placed on smaller airframes which is spurring a large increase in the number of Small Unmanned Aircraft Systems (SUAS) being deployed on the battlefield. The use of SUAS in combat is so new that no formal DoD wide reporting procedures have been established to track SUAS flight hours. As the capabilities grow for all types of UAS, nations continue to subsidize their research and development leading to further advances enabling them to perform a multitude of missions. UAS no longer only perform intelligence, surveillance, and reconnaissance missions, although this still remains their predominant type. Their roles have expanded to areas including electronic attack, strike missions, suppression and/or destruction of enemy air defense, network node or communications relay, combat search and rescue, and derivations of these themes. These UAS range in cost from a few thousand dollars to tens of millions of dollars, with aircraft ranging from less than one pound to over 40,000 pounds.

When the Obama administration announced in December 2009 the deployment of 30,000 new troops in Afghanistan, there was already an increase of attacks by pilotless Predator drones against Taliban and Al Qaeda militants in Afghanistan and Pakistan's tribal areas, of which one probably killed a key member of Al Qaeda. However, neither Osama bin Laden nor Ayman al-Zawahiri was the likely target, according to reports. According to a report of the New America Foundation, armed drone strikes had dramatically increased under President Obama – even before his deployment decision. There were 43 such attacks between January and October 2009. The report draws on what it deems to be "credible" local and national media stories about the attacks. That compared with a total of 34 in all of 2008, President Bush’s last full year in office. Since 2006, drone-launched missiles allegedly had killed between 750 and 1,000 people in Pakistan, according to the report. Of these, about 20 people were said to be leaders of Al Qaeda, Taliban, and associated groups. Overall, about 66 to 68 percent of the people killed were militants, and between 31 and 33 percent were civilians. US officials disputed the assertion that up to 30 percent of the victims of the unmanned aerial vehicle attacks were civilians [22].

UAV functions

UAVs perform a wide variety of functions. The majority of these functions are some form of remote sensing; this is central to the reconnaissance role most UAVs fulfill. Less common UAV functions include interaction and transport.

Remote sensing

A Bell Eagle Eye, offered to the US Coast Guard
The RQ-7 Shadow is capable of delivering a 20 lb "Quick-MEDS" canister to front-line troops

UAV remote sensing functions include electromagnetic spectrum sensors, biological sensors, and chemical sensors. A UAV's electromagnetic sensors typically include visual spectrum, infrared, or near infrared cameras as well as radar systems. Other electromagnetic wave detectors such as microwave and ultraviolet spectrum sensors may also be used, but are uncommon. Biological sensors are sensors capable of detecting the airborne presence of various microorganisms and other biological factors. Chemical sensors use laser spectroscopy to analyze the concentrations of each element in the air.

Transport

UAVs can transport goods using various means based on the configuration of the UAV itself. Most payloads are stored in an internal payload bay somewhere in the airframe. For many helicopter configurations, external payloads can be tethered to the bottom of the airframe. With fixed wing UAVs, payloads can also be attached to the airframe, but aerodynamics of the aircraft with the payload must be assessed. For such situations, payloads are often enclosed in aerodynamic pods for transport.

Scientific research

Unmanned aircraft are uniquely capable of penetrating areas which may be too dangerous for piloted craft. The National Oceanic and Atmospheric Administration (NOAA) began utilizing the Aerosonde unmanned aircraft system in 2006 as a hurricane hunter. AAI Corporation subsidiary Aerosonde Pty Ltd. of Victoria (Australia), designs and manufactures the 35-pound system, which can fly into a hurricane and communicate near-real-time data directly to the National Hurricane Center in Florida. Beyond the standard barometric pressure and temperature data typically culled from manned hurricane hunters, the Aerosonde system provides measurements far closer to the water’s surface than previously captured. Further applications for unmanned aircraft can be explored once solutions have been developed for their accommodation within national airspace, an issue currently under discussion by the Federal Aviation Administration. UAVSI, the UK manufacturer also produce a variant of their Vigilant light UAS (20 kg) designed specifically for scientific research in severe climates such as the Antarctic.

Fulmar UAV, developed by Aerovision for civilian applications
UAV Stardust II, developed under sUAS ARC FAA

Armed attacks

IAI Heron , an Unmanned Aerial Vehicle developed by the Malat (UAV) division of Israel Aerospace Industries.

MQ-1 Predator UAVs armed with Hellfire missiles are now used as platforms for hitting ground targets in sensitive areas. Armed Predators were first used in late 2001 from bases in Pakistan and Uzbekistan, mostly for hitting high profile individuals (terrorist leaders etc.') inside Afghanistan. Since then, there were several reported cases of such attacks taking place in Pakistan, this time from Afghan-based Predators. The advantage of using an unmanned vehicle, rather than a manned aircraft in such cases, is to avoid a diplomatic embarrassment should the aircraft be shot down and the pilots captured, since the bombings took place in countries deemed friendly and without the official permission of those countries.[23][24][25][26]

A Predator, based in a neighboring Arab country, was used to kill suspected al-Qaeda terrorists in Yemen on November 3, 2002. This marked the first use of an armed Predator as an attack aircraft outside of a theater of war such as Afghanistan.[27]

Questions have been raised about the accuracy of the targeting of UAVs. In March 2009, The Guardian reported that Israeli UAVs armed with missiles killed 48 Palestinian civilians in the Gaza Strip, including two small children in a field and a group of women and girls in an otherwise empty street.[28] In June, Human Rights Watch investigated six UAV attacks which resulted in civilian casualties, and found that Israeli forces either failed to take all feasible precautions to verify that the targets were combatants, or failed to distinguish between combatants and civilians.[29][30][31] In July 2009, Brookings Institution released a report stating that in the United States-led drone attacks in Pakistan, ten civilians died for every militant killed.[32][33] S. Azmat Hassan, a former ambassador of Pakistan, said in July 2009 that American UAV attacks were turning Pakistani opinion against the United States, and that 35 or 40 such attacks only killed 8 or 9 top al-Qaeda operatives.[34]

One issue with civilian casualties is the relative lack of discretion of the 100-lb Hellfire, which was designed to eliminate tanks and attack bunkers.[35] The Raytheon Griffin is being fielded as a more discreet alternative, and development is underway on the still smaller, US Navy-developed Spike missile.[36] The payload-limited Predator A can also be armed with six Griffin missiles, as opposed to only two of the much-heavier Hellfires.

Search and rescue

UAVs will likely play an increased role in search and rescue in the United States. This was demonstrated by the successful use of UAVs during the 2008 hurricanes that struck Louisiana and Texas.

For example, Predators, operating between 18,000–29,000 feet above sea level, performed search and rescue and damage assessment. Payloads carried were an optical sensor (which is a daytime and infra red camera) and a synthetic aperture radar. The Predator's SAR is a sophisticated all-weather sensor capable of providing photographic-like images through clouds, rain or fog, and in daytime or nighttime conditions; all in real-time. A concept of coherent change detection in SAR images allows for exceptional search and rescue ability: photos taken before and after the storm hits are compared and a computer highlights areas of damage.[37][38]

Design and development considerations

UAV design and production is a global activity, with manufacturers all across the world. The United States and Israel were initial pioneers in this technology, and U.S. manufacturers have a market share of over 60% in 2006, with U.S. market share due to increase by 5-10% through 2016.[39] Northrop Grumman and General Atomics are the dominant manufacturers in this industry, on the strength of the Global Hawk and Predator/Mariner systems.[39] Israeli and European manufacturers form a second tier due to lower indigenous investments, and the governments of those nations have initiatives to acquire U.S. systems due to higher levels of capability.[39] European market share represented just 4% of global revenue in 2006.[39]

Development costs for American military UAVs, as with most military programs, have tended to overrun their initial estimates. This is mostly due to changes in requirements during development and a failure to leverage UAV development programs over multiple armed services. This has caused United States Navy UAV programs to increase from zero to five percent in cost while United States Air Force UAV programs have increased from 60 to 284 percent.[40]

Degree of autonomy

UAV monitoring and control at CBP
HiMAT Remote Cockpit Synthetic Vision Display (Photo: NASA 1984)

Early UAVs used during the Vietnam War after launch captured video that was recorded to film or tape on the aircraft. These aircraft often were launched and flew either in a straight line or in preset circles collecting video until they ran out of fuel and landed. After landing, the film was recovered for analysis. Because of the simple nature of these aircraft, they were often called drones. As new radio control systems became available, UAVs were often remote controlled and the term "remotely piloted vehicle" came into vogue. Today's UAVs often combine remote control and computerized automation. More sophisticated versions may have built-in control and/or guidance systems to perform low-level human pilot duties such as speed and flight-path stabilization, and simple scripted navigation functions such as waypoint following. In news and other discussions, often the term "drone" is still mistakenly used to refer to these more sophisticated aircraft.

From this perspective, most early UAVs are not autonomous at all. In fact, the field of air-vehicle autonomy is a recently emerging field, whose economics is largely driven by the military to develop battle-ready technology. Compared to the manufacturing of UAV flight hardware, the market for autonomy technology is fairly immature and undeveloped. Because of this, autonomy has been and may continue to be the bottleneck for future UAV developments, and the overall value and rate of expansion of the future UAV market could be largely driven by advances to be made in the field of autonomy.

Autonomy technology that is important to UAV development falls under the following categories:

Autonomy is commonly defined as the ability to make decisions without human intervention. To that end, the goal of autonomy is to teach machines to be "smart" and act more like humans. The keen observer may associate this with the development in the field of artificial intelligence made popular in the 1980s and 1990s such as expert systems, neural networks, machine learning, natural language processing, and vision. However, the mode of technological development in the field of autonomy has mostly followed a bottom-up approach, such as hierarchical control systems[41], and recent advances have been largely driven by the practitioners in the field of control science, not computer science . Similarly, autonomy has been and probably will continue to be considered an extension of the controls field.

To some extent, the ultimate goal in the development of autonomy technology is to replace the human pilot. It remains to be seen whether future developments of autonomy technology, the perception of the technology, and most importantly, the political climate surrounding the use of such technology, will limit the development and utility of autonomy for UAV applications. Also as a result of this, synthetic vision for piloting has not caught on in the UAV arena as it did with manned aircraft. NASA utilized synthetic vision for test pilots on the HiMAT program in the early 1980s (see photo), but the advent of more autonomous UAV autopilots, greatly reduced the need for this technology.

Interoperable UAV technologies became essential as systems proved their mettle in military operations, taking on tasks too challenging or dangerous for troops. NATO addressed the need for commonality through STANAG (Standardization Agreement) 4586. According to a NATO press release, the agreement began the ratification process in 1992. Its goal was to allow allied nations to easily share information obtained from unmanned aircraft through common ground control station technology. STANAG 4586 — aircraft that adhere to this protocol are equipped to translate information into standardized message formats; likewise, information received from other compliant aircraft can be transferred into vehicle-specific messaging formats for seamless interoperability. Amendments have since been made to the original agreement, based on expert feedback from the field and an industry panel known as the Custodian Support Team. Edition Two of STANAG 4586 is currently under review. There are many systems available today that are developed in accordance with STANAG 4586, including products by industry leaders such as AAI Corporation, CDL Systems, and Raytheon, all three of which are members of the Custodian Support Team for this protocol.

Endurance

RQ-4 Global Hawk, a high-altitude reconnaissance UAV capable of 36 hours continuous flight time

Because UAVs are not burdened with the physiological limitations of human pilots, they can be designed for maximized on-station times. The maximum flight duration of unmanned, aerial vehicles varies widely. Internal-combustion-engine aircraft endurance depends strongly on the percentage of fuel burned as a fraction of total weight (the Breguet endurance equation), and so is largely independent of aircraft size. Solar-electric UAVs hold potential for unlimited flight, a concept originally championed by the AstroFlight Sunrise in 1974[42][43][44][45] and the much later Aerovironment Helios Prototype, which was destroyed in a 2003 crash.

Electric UAVs kept aloft indefinitely by laser power-beaming [46] technology represent another proposed solution to the endurance challenge. This approach is advocated by Jordin Kare and Thomas Nugent.

One of the major problems with UAVs is no capability for inflight refueling. Currently the US Air Force is promoting research that should end in an inflight UAV refueling capability, which should be available by 2010.

One of the uses for a high endurance UAV would be to "stare" at the battlefield for a long period of time to produce a record of events that could then be played backwards to track where improvised explosive devices (IEDs) came from. Air Force Chief of Staff John P. Jumper started a program to create these persistent UAVs, but this was stopped once he was replaced.[47]

The Defense Advanced Research Projects Agency (DARPA) is to sign a contract on building an UAV which should have an enormous endurance capability of about 5 years. The project is entitled "Vulture". The developers are certain neither on the design of the UAV nor on what fuel it should run to be able to stay in air without any maintenance for such a long period of time.[48]

Notable high endurance flights
UAV Flight time Date Notes
QinetiQ Zephyr Solar Electric 82 hours 37 minutes 28–31 July 2008 [49]
Boeing Condor 58 hours, 11 minutes 1989 The aircraft is currently in the Hiller Aviation Museum, CA.

[50]
QinetiQ Zephyr Solar Electric 54 hours September 2007 [51][52]
IAI Heron 52 hours  ? [53]
AC Propulsion Solar Electric 48 hours, 11 minutes June 3, 2005 [54]
MQ-1 Predator 40 hours, 5 minutes  ? [55]
GNAT-750 40 hours 1992 [56][57]
TAM-5 38 hours, 52 minutes August 11, 2003 Smallest UAV to cross the Atlantic

[58][59]
Aerosonde 38 hours, 48 minutes May 3, 2006 [60]
I-GNAT 38 hours, landed with 10-hour reserve  ? [61]
RQ-4 Global Hawk 36 hours  ? [62][63]
Aerosonde "Laima" 26 hours, 45 minutes August 21, 1998 First UAV to cross the Atlantic

[64][65]
TAI Anka 24 hours March 2010 [66] [62][63][67]
Vulture (UAV) Has not flown. Potential endurance 5 years  ? A DARPA project[48]
RQ-2 Pioneer 5.5 Hours  ? The US Navy retrieves the Pioneer by flying it into a large net.
RQ-7 Shadow 4 Hours  ? Used by both the US Army and the US Marine Corps.
RQ-11 Raven 80 min.  ? The Raven UAV can be launched by throwing it into the air.
MQ-8 Fire Scout +5 hours  ? The MQ-8 is designed to autonomously take off and land on any aviation-capable ship or confined land area.

Existing UAV systems

UAVs have been developed and deployed by many countries around the world. For a list of models by country, see : List of unmanned aerial vehicles

The export of UAVs or technology capable of carrying a 500 kg payload at least 300 km is restricted in many countries by the Missile Technology Control Regime.

Other information

US Navy UAVs in Action, Neubeck, (Squadron/Signal Publications 2010)

See also

Historic
Facilities, units and programs
Other types of unmanned vehicles
Intelligence

References

  1. ↑ 1.0 1.1 Pir Zubair Shah, "Pakistan Says U.S. Drone Kills 13", New York Times, June 18, 2009.
  2. ↑ David Axe, "Strategist: Killer Drones Level Extremists’ Advantage", Wired, June 17, 2009.
  3. ↑ 3.0 3.1 3.2 Taylor, A. J. P. Jane's Book of Remotely Piloted Vehicles.
  4. ↑ Wagner p. xi
  5. ↑ Wagner p. xi, ,xii
  6. ↑ Wagner p. xii
  7. ↑ Wagner p. 79
  8. ↑ Wagner p. 78 & 79 photos
  9. ↑ Wagner p. 202
  10. ↑ Wagner p. 200 & 212
  11. ↑ Wagner p. 208
  12. ↑ Wagner p. 208
  13. ↑ Levinson, Charles (January 13, 2010). "Israeli Robots Remake Battlefield". The Wall Street Journal. p. A10. http://online.wsj.com/article/SB126325146524725387.html. Retrieved January 13, 2010. 
  14. ↑ [1]
  15. ↑ History of Unmanned Aerial Vehicles
  16. ↑ Comparison of USAF Tier II, II+ and III- systems
  17. ↑ http://www.edwards.af.mil/articles98/docs_html/splash/may98/cover/Tier.htm USAF Tier system
  18. ↑ USMC powerpoint presentation of tier system
  19. ↑ Detailed description of USMC tier system
  20. ↑ 20.0 20.1 [2]
  21. ↑ http://www.acq.osd.mil/usd/Roadmap%20Final2.pdf#search=%22Dod%20UAS%20Roadmap%202005%22
  22. ↑ "Drone aircraft in a stepped-up war in Afghanistan and Pakistan" Iran design uav engine WWW.UAV.IR
  23. ↑ Fox News
  24. ↑ Defense Industry Daily
  25. ↑ MSNBC
  26. ↑ Globe and Mail
  27. ↑ Federation of American Scientists
  28. ↑ The Guardian, 23 March 2009. "Cut to pieces: the Palestinian family drinking tea in their courtyard: Israeli unmanned aerial vehicles—the dreaded drones—caused at least 48 deaths in Gaza during the 23-day offensive." Retrieved on August 3, 2009.
  29. ↑ "Precisely Wrong: Gaza Civilians Killed by Israeli Drone-Launched Missiles", Human Rights Watch, 30 June 2009.
  30. ↑ "Report: IDF used RPV fire to target civilians", YNET, 30 June 2009
  31. ↑ "Israel/Gaza: Civilians must not be targets: Disregard for Civilians Underlies Current Escalation". Human Rights Watch. 2008-12-30. http://www.hrw.org/en/news/2008/12/30/israelgaza-civilians-must-not-be-targets. Retrieved 2009-08-03. 
  32. ↑ Drones kill 10 civilians for one militant: US report, Dawn (newspaper), 2009-07-21
  33. ↑ "Do Targeted Killings Work?", Brookings Institution, 2009-07-14
  34. ↑ Newsweek, July 8, 2009. Anita Kirpalani, "Drone On. Q&A: A former Pakistani diplomat says America's most useful weapon is hurting the cause in his country." Retrieved on August 3, 2009.
  35. ↑ Smaller, Lighter, Cheaper William Matthew; Defense News; May 31, 2010
  36. ↑ Efforts Are Underway to Arm Small UAVs Aviation Week; Oct 17, 2008
  37. ↑ AP Texas News
  38. ↑ 2008 Search and Rescue Missions
  39. ↑ 39.0 39.1 39.2 39.3 "UAVs on the Rise." Dickerson, L. Aviation Week & Space Technology. January 15, 2007.
  40. ↑ Defense Acquisitions: Opportunities Exist to Achieve Greater Commonality and Efficiencies among Unmanned Aircraft Systems
  41. ↑ Shim, D. H, Kim, H. J., Sastry, S., Hierarchical Control System Synthesis for Rotorcraft-based Unmanned Aerial Vehicles.
  42. ↑ Boucher, Roland (undated). "Project Sunrise pg 1". http://www.projectsunrise.info/First_Solar_Powered_Aircraft.html. Retrieved 2009-09-23. 
  43. ↑ Boucher, Roland (undated). "Project Sunrise pg 13". http://www.projectsunrise.info/Flight__Tests.html. Retrieved 2009-09-23. 
  44. ↑ Newcome, Laurence R. (2004). Unmanned aviation: a brief history of unmanned aerial vehicles. http://books.google.com/books?isbn=1563476444. Retrieved 2009-09-23. 
  45. ↑ Curry, Marty (March 2008). "Solar-Power Research and Dryden". http://www.nasa.gov/centers/dryden/news/FactSheets/FS-054-DFRC.html. Retrieved 2009-09-15. 
  46. ↑ "Wireless Power for UAVs". 2010. http://lasermotive.com/wp-content/uploads/2010/04/Wireless-Power-for-UAVs-March2010.pdf. 
  47. ↑ counter_ied_backtracking.mpg
  48. ↑ 48.0 48.1 Vulture - The Unmanned Aircraft Able to Stay in the Air for 5 Years
  49. ↑ QinetiQ press release
  50. ↑ Hiller Aviation Museum reference to the flight
  51. ↑ QinetiQ press release
  52. ↑ New Scientist article
  53. ↑ NOVA PBS TV program reference IAI reference
  54. ↑ AC Propulsion release describing the flight
  55. ↑ UAV Forum reference Federation of American Scientists reference
  56. ↑ Directory of US Military Rockets and Missiles reference to the flight
  57. ↑ UAV Endurance Prehistory reference
  58. ↑ TAM Homepage
  59. ↑ TAM-5 FAQ page
  60. ↑ Aerosonde release on the flight
  61. ↑ General Atomics reference to the flight
  62. ↑ 62.0 62.1 Space Daily story on the flight
  63. ↑ 63.0 63.1 RAND Corporation report
  64. ↑ Aerosonde Laima page
  65. ↑ Seattle Museum of Flight
  66. ↑ http://www.defense-update.com/products/t/tiha_17052010.html
  67. ↑ http://www.flightglobal.com/directory/uav/turkish-aerospace-industries-20766/tiha-b-7448.html
  68. ↑ Federation of American Scientists. Pioneer Short Range (SR) UAV. Accessed 26 November 2006.
  69. ↑ National Air and Space Museum, Smithsonian Institution. Pioneer RQ-2A 14 September 2001. Accessed 26 November 2006.
  70. ↑ Senator Bill Nelson (January 28, 2004) "New Information on Iraq's Possession of Weapons of Mass Destruction", Congressional Record
  71. ↑ Lowe, C. (December 16, 2003) "Senator: White House Warned of UAV Attack," Defense Tech
  72. ↑ Hammond, J. (November 14, 2005) "The U.S. 'intelligence failure' and Iraq's UAVs" The Yirmeyahu Review
  73. ↑ Pilotless Warriors Soar To Success, www.cbsnews.com, 25 April 2004. Accessed 21 April 2007.

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