This post is an excerpt of the last section of United States
Congressinoal Research Service report R42136. I extracted the last
section to show the recently slowed-down U.S. UAS development
pace. The reason behind this slowness is yet to be discovered.
In the mid-1990s, the Pentagon began developing a UAS designed primarily for combat missions.
The result was two separate Unmanned Aerial Combat Vehicles (UCAV) programs, the Air
Force’s UCAV and the Navy’s UCAV-N demonstrator program. The Air Force favored Boeing’s
X-45 for its program, while Northrop Grumman’s X-47 Pegasus and Boeing’s X-46 competed for
the Navy’s project. However, in June 2003, the Pentagon merged the two programs in order to
establish the Joint Unmanned Combat Air System (J-UCAS) project under the management of the
Defense Advanced Research Projects Agency (DARPA). The objective of the J-UCAS merger
was to create a flexible offensive network in which the air and ground elements are adapted to
meet specific combat missions. As part of Program Budget Decision (PBD) 753 in December
2004, DARPA was ordered to transfer administration of the J-UCAS resources to Air Force. J-
UCAS was cancelled in 2006. The total money spent on the J-UCAS/UCAV program, which
reached more than $1.45 billion in RDT&E funding, made it one of the most expensive UAS
ventures undertaken by DOD.
Subsequently, in May 2010, the Navy issued a Request for Information for a carrier-borne UCAV
seeking ideas on a stealthy strike/surveillance platform that could operate alongside manned
aircraft as part of a carrier air wing by the end of 2018. The notional system would comprise
four to six aircraft capable of autonomous operation from Nimitz- and Ford-class carriers,
with an unrefueled endurance of 11-14 hours and the capability for both hose-and-drogue
and boom-and-probe aerial refueling.
Another significant attribute of UCLASS is that—unlike most current UAS that are designed to
operate only in permissive or lightly defended environments—UCLASS “must be capable of
operating in hostile airspace, which means the aircraft design must feature low-observable
traits.” Navy Secretary Ray Mabus said that “The notion here is that—just like the F-35 carrier
version—it is going to be stealthy. It is going to be low observable,” he says. “And, if you are
going to integrate an airplane into the carrier air wing, it should be able to go into contested
Northrop Grumman’s X-47B, an advanced version of the X-47A UCAV-N contender, is nearly 36
feet long, with a wingspan of 62 feet. The increased wingspan in combination with the Pratt &
Whitney F100-220U turbojet engine may allow X-47B an endurance of nine hours and range of
1,600 nautical miles. The X-47B features folding wing-tips that cut down on size, making it more
suitable for storage aboard an aircraft carrier.
System Characteristics. 36 feet long with a wingspan of 50 feet; single GE F404-102D engine.
The X-45C was expected to achieve speeds of 450 knots and altitudes of 40,000 feet, with a flight
duration of up to seven hours and a range of 1,200 nautical miles.
General Atomics is currently developing a third generation Predator that uses a turbojet engine to
fly long-endurance, high-altitude surveillance missions. The Avenger (formerly “Predator C”)
will reportedly use the fuselage of the Reaper, but will be similar to Northrop Grumman’s Global
Hawk in payload capacity and flight performance. General Atomics confirmed its offer of the
“Sea Avenger” variant for the UCLASS competition in 2010.
With a 41-foot long fuselage and 66-foot wingspan, the Avenger is capable of staying in the
air for up to 20 hours, and operating at up to 50,000 feet. Powered by a 4,800-lb. thrust Pratt
& Whitney PW545B jet engine, it can fly at over 400 knots—50 percent faster than the
turboprop-powered Reaper unmanned plane, and more than three times as quick as the
General Atomics says the first Avenger is now flying two to three times a week…. A second
and third Avenger are now in production. It’ll be a little longer than the first—44 feet—and
able to haul a 6,000 pound payload. That’s a 50 percent improvement over what the Reaper
Tactical UAS, ranging from Raven to Reaper, have become familiar, and the prototypes of
combat UAS like UCLASS are already in the air. But a new class of UAS is under development
that would move beyond the endurance and range of Global Hawk to provide much more
persistent platforms for ISR, data relay, and other purposes. Among these HALE, for high altitude
long endurance systems, are:
Proposed by the Boeing Phantom Works, Phantom Eye would use hydrogen-fueled automobile
engines to carry a 3,000-pound payload for 10 days. A 150-foot wingspan demonstrator version
hopes to achieve “up to four days of endurance at 65,000 ft.” with a first flight in autumn 2011.
In 2009, Aurora Flight Sciences unveiled the Orion, which would use hydrogen-fueled diesel
engines to carry a 2,600-pound payload at 30,000 feet, or a 1,000-pound payload for 10 days at
15,000-20,000 feet. Its demonstrator version is designed to reach 5-day endurance with the
same payload. Orion is part of a system called MAGIC, an acronym for Medium-Altitude
Global ISR and Communications, being developed by under a $4.7-million contract from the Air
Force Research Laboratory.
Several firms (Lockheed Martin, MAV6, Northrop Grumman, and others) are developing
unmanned airships for long- to extremely long-endurance missions. “In comparison with
unmanned fixed-wing aircraft, such as the Global Hawk or Reaper, an airship … would have a
similar payload and substantially longer endurance but considerably slower cruise speed.” The
Army’s High Altitude Airship program “has the long-term objective of building an airship
capable of carrying a 2,000-pound payload and generating 15 kilowatts of power (to run the
payload and aircraft systems) at 65,000 feet for more than 30 days.”[^1]
[^1]: Ibid. For more information on lighter-than-air platforms, see
CRS Report RS21886, Potential Military Use of Airships and
Aerostats, by Christopher Bolkcom.