led to the engine internal failure.
Another loss was when on June 20, 2019, Iran shot down a Global Hawk with a surface‐to‐air missile over the Strait of Hormuz. Iran said that the UAV violated its airspace, while US officials responded that the air vehicle was flying in international airspace.
These real stories provided valuable lessons and presented expensive experiences for young UAV designers. As typical of any development program, the Global Hawk design changed as the result of flight tests.
1.6 Predator Family
1.6.1 Predator Development
RQ‐1 Predator is a long‐endurance, medium‐altitude unmanned aircraft system for surveillance, reconnaissance, and attack missions, designed and manufactured by General Atomics Aeronautical Systems.
The Predator had an unconventional development cycle with origins going back to a project by Abraham E. Karem. He is a pioneer in innovative fixed and rotary‐wing unmanned vehicles and is regarded as one of the founding fathers of UAV technology. Initially, by 1983, a small long‐endurance tactical reconnaissance UAV prototype was developed called the Albatross for the DARPA. Then, by 1988, further development resulted in a more advanced design, the Amber, which was followed by the GNAT 750. Karem’s company (Karem Aircraft, Inc.) and its UAV were soon acquired by General Atomics.
The CIA utilized the GNAT 750 in military operations over Bosnia in 1993 and 1994. The program suffered from a few weaknesses, but it held enough promise that the DOD expressed interest in a larger, more advanced version of the GNAT 750 for medium‐altitude reconnaissance, then designated RQ‐1 Predator. By 1995, it became operational over Bosnia. In parallel, the Air Force saw the Predator as a new tool in tactical reconnaissance with the added benefit of a live satellite data link.
In the late 1990s, Predator’s capability was expanded to include a laser designator to illuminate targets and guide weapons dropped from other aircraft. In 1999, the UAV had its first significant test during Operation Allied Force in Kosovo. By 2000, due to concern over the rising threat of al Qaeda, the Predator was scheduled for arming with the Hellfire laser‐guided missile.
After the September 11, 2001 attacks, the armed Predator become fully operational, and by January 2003, flew 164 missions over Afghanistan. The armed Predator – capable of both reconnaissance and attack missions – has continued to have a pivotal role in combat operations. In 2002, the Air Force adapted a Predator to carry Stinger missiles and attempted an air‐to‐air engagement with an Iraqi MiG‐25, but resulted in the loss of the Predator.
Predator UAVs have been operational since 1995 in support of NATO, UN, and US operations, and as part of Operation Enduring Freedom in Afghanistan and Operation Iraqi Freedom, flying more than 500,000 flight hours. The US Air Force Predator production ended in 2011 with 268 air vehicles manufactured. Hundreds of Predators have been sold to a number of countries including Italy, Spain, France, UK, Australia, Netherlands, Canada, and Germany.
This military UAV has been used in the Balkans, Afghanistan, Iraq, and other global locations. By 2011, the US military had nearly 11,000 UAVs on their inventory, including hundreds of Predators. The Predator was retired in 2018. The Predator‐series family encompasses MQ‐1 Predator, MQ‐1C Gray Eagle, MQ‐9 Reaper (Predator B), MQ‐9B SkyGuardian, and Predator C Avenger.
1.6.2 Reaper
After about 10 years of Predator operations, and when some weaknesses were identified, new challenges arose in employing Predator. DOD decided to have a new version of Predator with enhanced performance features and an advanced design. The operation requirements included such performance items as a faster cruising speed and higher flight altitude, and also heavier and more advanced payloads. The conceptual design and the air vehicle configuration were almost kept. The only major configuration change was to have a V‐tail instead of an inverted V‐tail.
The US Air Force first deployed the MQ‐9 Reaper (developed by General Atomics, then called Predator B) to Afghanistan in October 2007 for precision airstrikes and it slowly began replacing the Predator. The General Atomics MQ‐9 Reaper (Figure 1.5) flew its first operational mission in Iraq in July 2008. In the meantime, the Army began development of a refined derivative, the MQ‐1C Gray Eagle, which began operations in 2012. The US Air Force retired the Predator in 2018, replacing it with the Reaper.
Figure 1.5 General Atomics MQ‐9 Reaper
Left: A British MQ‐9A Reaper operating over Afghanistan in 2009
(Source: Tam McDonald / Wikimedia Commons / OGL v1.0).
Right: CBP’s Reaper
(Source: Gerald L. Nino / Wikimedia Commons / Public Domain)
The first version of Predator (A) had a piston engine, but the upgraded Predator B, or MQ‐9 Reaper, is equipped with a turboprop engine (with a greater power). Predator B is larger, much heavier, with an improved flight performance (e.g., faster cruise speed, longer range, and longer endurance) than the earlier MQ‐1 Predator.
There are two groups of Payloads: (1) surveillance imagery sensors, which include a synthetic aperture radar, electro‐optic video, and forward‐looking infrared (FLIR) cameras, (2) weapon payloads, which include four anti‐armor missiles AGM‐114 Hellfire), two laser‐guided bombs (GBU‐12), and 500 lb joint direct attack munition. Other payload options include a laser designator and rangefinder, electronic support and countermeasures, a moving target indicator (MTI), and an airborne signals intelligence payload.
1.6.3 Features
Reaper UAV has a single turboprop engine on the rear fuselage, a fixed tricycle landing gear, a high aspect ratio wing, with a V‐tail. It has an aileron for roll control and a ruddervator for longitudinal and directional control. The air vehicle is equipped with UHF and VHF radio relay links, a C‐band line‐of‐sight data link, which has a range of 150 nm, and UHF and Ku‐band satellite data links.
The ground control station (GCS) is built into a single 30 ft trailer, containing pilot and payload operator consoles, three data exploitation and mission planning consoles, and two synthetic aperture radar workstations together with satellite and line‐of‐sight ground data terminals. The GCS also includes a data distribution system, which is equipped with a 5.5 m dish antenna or Ku‐band ground data terminal and a 2.4 m dish antenna for data dissemination. The flight can be controlled through line‐of‐site data links or through Ku‐band satellite links to produce a continuous video. Some mass and geometry features as well as flight performance of Reaper are provided in Table 1.2.
Predator and Reaper still have two major weaknesses: (1) the inability to operate in contested airspace with effective enemy air defenses and (2) jamming. These highlight the advances required for future Reaper versions to maintain its operational significance. Jamming can pose a significant threat to the Predator’s data links and GPS navigation.
Table 1.2 Reaper data and performance
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