Members Area
Username:

	AWARDS
	CALENDAR OF EVENTS
	DIRECTORS & OFFICERS
	HISTORY
	JOB OPPORTUNITIES
	KID'S PAGE
	LOCAL CHAPTER MEETINGS
	MEMBERSHIP
	NOVELTIES
	PUBLICATIONS
	VERTICAL FLIGHT FOUNDATION
	WWW LINKS

On February 9, 2000, the U.S. Navy announced the winner of the Engineering and Manufacturing Development (EMD) contract for their next-generation unmanned air vehicle, the Vertical Takeoff and Landing Tactical Unmanned Aerial Vehicle (VTUAV). The $93.7 million contract was awarded by the Program Executive Office for Cruise Missiles and Unmanned Aerial Vehicles to Northrop Grumman’s Ryan Aeronautical Center, San Diego, to fully develop their Model 379 VTOL UAV. Full-rate production is scheduled to begin in 2003, with initial operational capability that summer.

The main roles of the VTUAV are to be reconnaissance, surveillance, targeting and intelligence gathering, using a combination infrared/optical sensor and a laser target designator. The Navy also envisions using an improved version for search and rescue: the UAV would home in on an emergency beacon and drop a line when overhead. Another use would be to carry a Common Data Link (CDL) and serve as a radio/data relay platform. The VTUAV will allow a leap forward in payload sensor capability for naval surface fire, acting as a force multiplier for ships equipped with Extended Range Guided Munitions, the Advanced Gun System of the DD-21 Land Attack Destroyer, and land attack missiles, providing real-time battle damage assessment (BDA).

Background

The VTUAV program is the most recent chapter in the Navy’s surprisingly long history of UAV systems, and the culmination of over 10 years of VTOL UAV development. The Navy’s first operational VTOL UAV system was the remotely piloted helicopter QH-50 DASH, or Drone Anti-Submarine Helicopter (see Figure 1). First introduced into operational service in January 1963, the QH-50 was designed to give surface warships standoff Anti-Submarine Warfare (ASW) attack capabilities through the use of a drone torpedo delivery platform. The DASH was piloted via radar by an officer located in a destroyer’s Combat Information Center (CIC) to the suspected location of an enemy submarine, where it would drop its payload of one Mk-46 or two Mk-44 torpedoes. The drone would then be flown back to the ship, provided it survived the sudden change in the configuration of the helicopter after the payload was dropped; over 400 were lost in operational use. Nearly 800 of all four QH-50 variants were delivered to the Navy between 1960 and 1969. Most QH-50s were withdrawn from service in the 60s; however, several were used as unmanned reconnaissance drones in the Vietnam War, and continue to serve today at White Sands Missile Range, New Mexico, for the US Army Strike Command.

The 1970’s saw several VTOL UAV proposals, such as the Bombardier (Canadair) CL-227 Sentinel, but received little consideration due to their cost and technical immaturity. Fixed wing UAVs were considered more mature platforms, and had demonstrated their utility in combat, most notably with Israeli forces in Lebanon in the early 1980s. As a result, the US Navy acquired the AAI Corporation/Israel Aircraft Industries (IAI) Pioneer UAV to operate from its Iowa-class battleships for reconnaissance, surveillance and target acquisition (RSTA) missions. The Pioneer has been a very successful system for the Navy, operating from battleships and Marine Corps amphibious ships. It has accumulated more than 20,000 flight hours since its introduction to the fleet in 1986. The high point of Pioneer’s operational history was its unprecedented success during Operation Desert Storm/Shield, where it was used heavily by the battleships operating off the coast of Kuwait for naval gunfire support and BDA. One of the more popular anecdotes from the war relates the attempts of Iraqi solders to surrender to a Pioneer dispatched from the USS Wisconsin, fearing the 2000 lb shells that were sure to follow the sound of the loud two-cycle engine powering the UAV circling overhead. Since the re-decommissioning of the battleships in 1991, Pioneer systems have been assigned to LPD amphibious ships. While the Pioneer demonstrated the utility of a sea-based UAV system, its performance and operational difficulties do not fit with the Navy’s future warfighting needs. As a fixed-wing aircraft, it requires a complex launch and recovery procedure to operate from small-deck ships, such as a rocket-assisted takeoff (RATO) and a net-captured recovery (see Figure 2), which often rips off the propeller, antennas or wing upon "landing." The UAV also requires 100 LL aviation gasoline, a volatile fuel not typically carried on naval ships for safety reasons. Pioneer systems are currently scheduled to be phased out by 2003.

Despite the difficulties presented by shipborne operations of fixed-wing UAVs, the Navy participated in the Tactical UAV (TUAV) program, intended to provide a common platform to the Army, Navy and Marines to replace their Hunter and Pioneer UAV systems, respectively. Performance goals included a 200 km range with a 3 to 4 hour endurance on-station, at a cost of $350,000 per vehicle (including payload). In May 1996, Naval Air Systems Command awarded a $52.6 million contract to Alliant Techsystems for a 24 month Advanced Concept Technology Demonstration (ACTD) of their Outrider UAV. The Outrider is a fixed-wing aircraft featuring a joined twin-wing design for high lift and low drag (Figure 3). Technical problems, schedule delays and poor performance plagued Outrider, but a total of 185 flights were eventually completed, including 150 with autopilot and 32 automatic takeoff and landings. Disappointed with Outrider’s performance and cost, the Navy and Marines were allowed by the Joint Requirements Oversight Council (JROC) to opt out of the program and pursue VTOL alternatives. Outrider completed a military utility assessment for the US Army at Fort Hood, Texas, in June 1998. The Army then staged a "fly-off" for its TUAV requirement in October 1999, which was ultimately won by AAI’s Shadow 200 UAV. All four of the competing UAV systems were fixed wing.

The Navy had not given up on VTOL UAVs with the award of the Outrider ACTD, but had in fact been fostering the continued development of VTOL aircraft since 1990 under several different demonstration programs. The first such program was the joint US-Canadian MAVUS (Maritime VTOL UAV System) program, designed to gain further operational experience with maritime UAVs and to develop system performance specifications for the next generation Navy UAV system. The first phase, known as MAVUS I, began with ground-based tests of the Bombardier CL-227 Sentinel at Naval Air Station, Patuxent River, Maryland, from April through September 1990. Following ground testing, a system was installed on the frigate USS Doyle and seven flights were conducted for a total of 65 flight hours. As part of these flights, the Sentinel participated in NATO trials in which data transmitted to the Doyle was re-broadcast to Canadian, Dutch and British naval ships. In 1992, the final stage of MAVUS I was completed at Ft. Sill, Oklahoma, when the Sentinel successfully demonstrated the first free-flight autonomous landing of a UAV using the UCARS (UAV Common Automatic Recovery System) system developed by the Sierra Nevada Corporation. MAVUS II was initiated in mid-1993 to demonstrate at-sea automatic recoveries aboard the Perry-class frigate USS Vandegrift. Despite the fact that only seven of eighteen planned flights were attempted, only two successful launches made, and one UAV was lost during its 4 month deployment in 1994, the program did meet its objectives. Three successful automatic approaches, including hovering over deck at a height of 3 meters in a ‘deck-following’ mode, demonstrated that the UCARS could enable automatic recovery of VTOL UAV systems in an at-sea environment.

In parallel with the MAVUS program, the TRUS (Tilt-Rotor UAV System) program aimed to demonstrate tilt-rotor UAV flying qualities and performance, and to evaluate their costs, benefits, and potential compatibility with shipboard systems. A non-developmental engineering study was completed between December 1991 and April 1992, followed by fabrication of two demonstration aircraft and first flight in July 1993. Flight tests were conducted in early 1994 at Yuma Proving Ground, Arizona, followed by further testing in June 1994 at Naval Air Station, Patuxent River, Maryland. The aircraft, dubbed Eagle Eye by its developer, Bell Helicopter Textron, successfully demonstrated transitions from hover mode to airplane mode and back, achieving a maximum forward airspeed of 158 kt in airplane mode.

The Vertical Launch And Recovery (VLAR) program, initiated in 1992, was intended to demonstrate and assess the technical risk of VTOL UAVs exploiting helicopter technologies beyond tilt-wing/rotor and axial/coaxial configurations. A request for information (RFI) was issued to industry in late 1992, seeking VLAR concepts utilizing vertical attitude, stopped rotor, jet lift, ducted fan, tilt-rotor and conventional helicopter technology. A competitive RFP was issued in September 1993, and a contract was awarded to The Boeing Company in May 1994 for demonstration of its Heliwing vertical attitude aircraft. The demonstrator aircraft was built in six months, and flight testing began in April 1995. The eighth of nine planned flights in June 1995 saw the first successful demonstration of a full transition from hover to airplane mode, but the vehicle was lost on approach due to an engine flame-out. Boeing chose not to fund and build a second aircraft, but finished the VLAR program through simulations, analysis and an engine risk-reduction study in lieu of further flight testing.

In 1997, the Navy began the Congressionally mandated VTOL Demonstrator program, with the purpose of evaluating current VTOL UAV maturity and technology risks associated with developing a complete system for Naval use. Three systems were selected for flight demonstrations, including the Bell Eagle Eye, the SAIC/ATI Vigilante and a production-standard Bombardier CL-327 Guardian. Unsuccessful bids were received from Eagle Systems, Sikorsky (Cypher), Freewing (Scorpion), and Dragonfly Pictures (DP-4). Each airframe was to complete 50 hours of ground-based flight testing over a two month period, operate from a 40 ft by 40 ft helicopter landing pad, and demonstrate two representative mission profiles. The Vigilante suffered from problems related to its flight control system, prompting SAIC and the Navy to agree to abandon its land-based trials. Both the Eagle Eye and Guardian vehicles completed the required testing in 1998, and were selected to participate in a second phase of sea-based testing in 1999.

The VTUAV Program

Encouraged by the progress shown by VTOL UAVs during the most recent demonstrations, the Navy released an RFP for the VTUAV program in August 1999. Bidders for the EMD contract were expected to include the Bombardier Guardian, SAIC/ATI Vigilante, Bell Eagle Eye, Sikorsky MARINER, and Northrop Grumman Ryan Aeronautical Center’s Model 379 UAV. Bombardier was considered a leading contender in the competition due to its long history of operating naval UAVs, but withdrew in September 1999 due to concerns over the Guardian’s ability to meet the Navy’s performance requirements. Although a comprehensive upgrade plan was in place after its withdrawal from the VTOL Demonstrator program, SAIC chose not to bid the Vigilante due to what it believed was a "punitive" contract fee arrangement. The Navy insisted on a no-profit contract for the VTUAV program, with the contractor assuming responsibility for half of any unexpected expenses incurred during the EMD phase. Potential competitors have also stated that the project is underfunded by about 50%.

The VTUAV requirements evolved from the Navy’s experience with the MAVUS, VLAR, TRUS and VTOL Demonstrator programs, as well as a general concept of operations developed from the Navy White Letters Forward…From the Sea and Operational Maneuver From the Sea. Performance parameters for the UAV system outlined in the operational requirements document (ORD) are given in Table 1, listing threshold and objective values for each. Parameters denoted with an asterisk are considered Key Performance Parameters, which must be met by the contractor to continue with the program.
 
 

The ORD calls for each VTUAV system to consist of four aircraft, two Ground Control Stations (GCS), four electro-optical/infrared (EO/IR) laser designator Modular Mission Payloads (MMP) and two Remote Data Terminals (RDT). The EMD contract will deliver one VTUAV system with options for three Low Rate Initial Production (LRIP) systems. These first three LRIP systems have already been designated for service to the Marine Corps, Navy and Naval Air Maintenance Training. The current requirement of 23 systems (a total of 92 aircraft), 12 for the Navy and 11 for the Marine Corps, are scheduled to achieve initial operational capability (IOC) in the fourth quarter of FY2003, with full operational capability less than two years later.

The Atlantic and Pacific fleets would each receive 24 air vehicles and six GCSs, with the remaining 12 GCSs allocated to LHA and LHD amphibious assault ships. The Marine Corps would assign 16 air vehicles and eight land-based GCSs each to its VMU-1 and VMU-2 expeditionary units, with 12 air vehicles and 6 GCSs allocated to the Maritime Prepositioning Force. The Navy hopes to deploy future VTUAV systems, for a total of 33 systems, aboard additional platforms such as aircraft carriers, destroyers and cruisers.

While the US Army, Navy and Marines could not agree to a common UAV system during the TUAV program, the systems they ultimately introduce into combat will all use the common Tactical Control System (TCS). The TCS, with which the VTUAV must be fully compatible, will provide a system for interoperable UAV employment by military operators and a common interface to joint and service Command, Control, Communications, Computers and Intelligence (C4I) systems. It will also establish an interoperability standard for operations and data dissemination for current and future military UAV systems.

Future Systems

The Navy is already studying requirements for future UAV systems, such as an aircraft with even greater range and payload capabilities than the VTUAV. The Multi-Role Endurance UAV (MRE-UAV) would be fielded between 2006 and 2014, and is intended for missions such as suppression of enemy air defenses (SEAD), C4I, surveillance, and reconnaissance. A Broad Agency Announcement (BAA) for studies of potential configurations and critical technologies for the MRE-UAV was released by Naval Air Systems Command in February 2000, and four study contract awards totaling $3.2 million were awarded to The Boeing Company, General Dynamics Information Systems, Lockheed Martin Aeronautics and Northrop Grumman’s Air Combat Systems on April 10.

Neither the BAA nor the draft Mission Needs Statement (MNS) explicitly indicate a desire for a VTOL UAV solution; however, the draft MNS does require the aircraft to operate from air-capable ships and austere locations. MRE-UAV performance goals outlined in a February 1996 requirements memorandum call for an aircraft with performance similar to the U.S. Air Force’s Predator UAV. The document specifies an aircraft with 24 hour on-station capability at a range of 500 nm, an EO/IR payload with a synthetic aperture radar (SAR), direct real-time receipt of imagery and satellite communications for beyond line-of-sight operations. Navy officials have considered a navalized version of the Predator, and produced estimates of $120 million to field such a system. The Predator would have to be adapted to naval use through the installation of a heavy fuel engine, development of automatic launch and recovery systems with capability for ship motion sensing, and modifications to operate from carrier-class ships. Many have considered it to be too complex for ship-based operations, but the Navy has yet to rule out the possibility of launching the MRE-UAV from aircraft carriers, despite resistance to the interruption of deck operations. An aircraft with a 24 hour on-station performance would have minimal effects, but obviously a VTOL UAV would solve these difficulties. The Navy is also considering using land-based Air Force Predators controlled at sea. Such joint operations were successfully demonstrated in 1995 and 1996, when a Predator was operated by a controller based in a carrier battle group and a submarine, respectively. Two developmental VTOL aircraft could also be considered as potential systems for the MRE-UAV or other future VTOL UAV requirements: the Boeing Canard Rotor/Wing (CRW) Dragonfly and Frontier Systems’ stealthy A160 Hummingbird. Both aircraft are currently under long-term development and flight demonstration contracts with the Defense Advanced Research Projects Agency (DARPA), attempting to significantly increase endurance of VTOL UAVs.

The Navy is also considering VTOL UAVs for missions other than reconnaissance, and recently began demonstrating their potential for logistics and resupply missions. Kaman is currently under contract to the U.S. Marines to convert one of its K-MAX medium-lift helicopters to an unmanned aircraft by mid-2000 as part of the Broad-area Unmanned Responsive Resupply Operations, or BURRO, program. The Office of Naval Research (ONR) and the Marines view unmanned VTOL aircraft such as the K-MAX as a way to save lives while performing "dirty, dull and dangerous" missions. The BURRO concept aims to reduce the risk to manned aircraft, such as the V-22 Osprey tilt-rotor, in highly lethal operating environments. By operating heavy-lift UAVs in conjunction with SLICE multi-task boats 15-20 nm out at sea, the Navy can provide rapid over-the-horizon sea-based logistics capability, keeping large ships away from hostile threats.

With VTOL UAVs now reaching a high level of technological maturity and consistently demonstrating their operability and utility in the military arena, we can expect that the VTUAV will be only the first of many VTOL UAV systems introduced into service by the US Navy in the 21^st century. While predictions that UAVs will completely replace manned military aircraft in the near future are a bit premature, VTOL UAVs are indeed poised to make a significant and lasting contribution to Naval aviation.
 

The QH-50 DASH (Drone Anti-Submarine Helicopter) was derived from the Gyrodyne Rotorcycle, which was designed for a US Navy contract seeking a small, portable helicopter capable of carrying one man for short distances.

Intended for ASW (Anti-Submarine Warfare) missions, the DASH was piloted remotely during takeoff and landing by an officer located near the flight deck, then flown via radar to its target by a second officer in the Combat Information Center (CIC), who would fly the aircraft via radar to the location of an enemy submarine. The DASH would then release its payload of one Mk-46 or two Mk-44 torpedoes, and fly back to the destroyer. The DASH was also designed to carry the Mk 57 nuclear depth bomb, but was never deployed due to the operational difficulties with the drones. Over 400 QH-50 drones were lost in operational use, prompting the Navy to cancel the DASH program in January 1971. The QH-50 has not faded into obscurity however; both the German SEAMOS and the Israeli HeliStar naval UAV programs use the Gyrodyne airframe.

Several versions of the QH-50 were built during its development. First flight of the optionally piloted QH-50A, powered by a 72 hp Porsche engine, was in December 1958, with its first unmanned shipboard landing in December 1960 on the destroyer USS Hazelwood. The QH-50B was very similar, but was powered by two 86 hp Porsche engines, and was a piloted craft only. The first production model, the QH-50C, became operational in January 1963. It included a large boost in horsepower compared to earlier variants, carrying a 270 shp Boeing T50-BO-15 engine. The final production configuration, the QH-50D, was powered by a 365 shp Boeing T50-BO-12 turboshaft engine turning two 20 ft diameter, counter-rotating fiberglass blades. Maximum gross takeoff weight was 2,303 lb with a useful load of almost 1,200 lb. The aircraft’s effective range was about 30 nm (limited by the range of the destroyer’s radar horizon), with an endurance of just over two hours. Maximum speed was 80 kt and cruising speed was 55 kt.
 

The CL-327 Guardian, an improved version of the CL-227 Sentinel, benefits from a developmental history that dates as far back as 1964. The Sentinel participated in the Navy MAVUS programs in the mid 1990s, with several demonstration flights culminating in a final demo at sea, landing on the USS Vandegrift and making several automatic approaches. A modified Sentinel, known as the Puma, was proposed to the US military for its TUAV program in 1996. The Guardian entered low rate production in 1996, with one system currently on short-term lease to the Royal Australian Army. The Guardian was one of three UAV systems selected to participate in the Navy VTOL UAV demonstration program in 1998. More than 50 hours of successful flights were completed, despite an accident in June 1998 when a fuel tank separated from the aircraft, causing fuel starvation and subsequent loss of the aircraft. Further technical problems have since plagued the vehicle, delaying planned shipborne tests until late 1999. Concern over the Guardian’s ability to meet the speed, payload, and endurance criteria prompted Bombardier to withdraw from the Navy VTUAV competition in September 1999.

The CL-327 Guardian is powered by a 125 shp Williams WTS117-5 turboshaft engine, which drives 13 ft diameter counter-rotating rotors. Gross takeoff weight is 772 lb, with an empty weight of 331 lb. Maximum endurance is reported at 6.25 hours, and the maximum cruise speed is given as 85 kt.
 

The Bell Eagle Eye is a twin tilt-rotor, all-composite aircraft, not unlike its much larger brother, the V-22 Osprey. The tilt-rotor system allows the UAV to cruise at fixed-wing aircraft speeds, while obtaining the vertical takeoff and landing capabilities desired by the Navy. The aircraft is powered by a single Rolls-Royce Allison 250-C20B turboshaft engine, turning two three-bladed, 9 ft diameter prop-rotors. Important performance specifications include a maximum takeoff weight of 2,250 lb, a service ceiling of 14,500 ft and a maximum cruising speed of 165 kt.

The tilt-rotor UAV was originally conceived in a joint effort between Bell Helicopter Textron and Boeing Helicopter begun in 1986. The first tilt-rotor demonstrator, the Bell/Boeing D-340 Pointer, made its first successful flight tests in 1988. Boeing dropped out of the program after 12 hours of test flights, and Bell continued on its own. The Eagle Eye was then developed under the TRUS program for an interoperable VTOL UAV. Two prototypes were first flown in 1993, and accumulated 15 hours of testing during 45 flights before the program was cancelled in 1994. Bell continued to develop the Eagle Eye with in-house research and development dollars until awarded a Navy contract in 1998 to test the Eagle Eye for the VTOL UAV flight demonstration program. The Eagle Eye was the only UAV of the recent bidders that was originally in the VTOL Demonstrator program. It is believed to have been the most capable, but also the most expensive, of the three systems.
 

The Heliwing was designed, built and flight tested to demonstrate the concept of a tail-sitting VTOL UAV which could transition to high-speed horizontal flight with a fixed wing/rotor design. Development of the Heliwing began in November 1993 on company funding, until Boeing was awarded a $2.6 million DoD contract in May 1994 under the VLAR program. A prototype flight-test vehicle was flown for the first time in April 1995, and had completed 99% of its test objectives before crashing due to engine flame-out on the eighth of nine planned flights. Boeing completed the VLAR program through the construction of a production-standard mission computer, performing simulations and carrying out risk-reduction studies of an upgraded airframe/engine combination. Boeing has also conducted internally funded research to define mission payloads and concepts of operation, and to examine international markets and partnerships. Missions envisioned for the Heliwing include RSTA, electronic countermeasures (ECM), anti-ship missile defense, communications relay and environmental sampling.

Two counter-rotating prop-rotors, powered by a Williams turbine engine, allow the Heliwing to take off and land vertically. The aircraft may then hover in helicopter mode, or accelerate laterally with its wing still vertical until transition speed is attained. At the transition speed, the aircraft starts to pitch over to a conventional flight attitude with the wing horizontal. The Heliwing can then fly at speeds approaching 200 kt in conventional airplane mode. Boeing reports that a typical operational mission would require 300 shp to lift its 1,200 lb gross takeoff weight, including a 200 lb payload. Maximum endurance for this configuration would be 6.5 hours, with a maximum dash speed of 187 kt. Its relatively short 17ft wingspan would allow a Perry-class frigate to accommodate 4 Heliwings in addition to a full-size helicopter.
 

Sikorsky’s MARINER (MARIne-Navy Extended-range Reconnaissance) UAV was developed in conjunction with General Dynamics Information Systems. No technical specifications of the MARINER have been released, however the proposal was reportedly based on a growth version of the Cypher II (shown). Also known as the Dragon Warrior, the Cypher II was recently selected by the US Marines for testing UAV operating concepts and payloads.

The Cypher family of UAVs employs a ducted fan consisting of two four-blade coaxial rotors to generate lift for hover mode. A conventional wing is attached to the annular fuselage for the Cypher II and MARINER variants to provide lift in forward flight, reducing the load on the lift fan. The wing, in conjunction with a second, smaller ducted fan at the tail of the aircraft used for forward propulsion, will greatly increase range and endurance for these variants. The Cypher II/Dragon Warrior is capable of carrying a 45 lb payload to a station 100 nm away and loitering for 2 hours. The all-composite aircraft has a maximum gross weight of 220 lb and a top speed of 125 kt. The wings may be removed for applications such as military operations in urban terrain (MOUT), like its predecessor, the Cypher I. Sikorsky is currently under a $5.46 million contract to deliver 2 prototypes and 4 ground stations, with a $3.76 million option to deliver 10 additional aircraft to production standard.
 

As the company’s name would imply, the Scorpion and Manta UAVs utilize a freewing concept, which allows the outer wing panels of the aircraft to operate at a constant angle of attack with variable incidence, exactly opposite of a normal aircraft. The wing is attached to the fuselage with spanwise hinges, allowing the wing to freely rotate. The advantage claimed is that the aircraft can therefore easily respond to gusts, allowing operability in windy conditions, less need for sensor stabilization, and increased airframe life and decreased airframe weight due to reduced gust loading. The Scorpion mates this concept with a tilt-body, which creates vectored thrust to obtain ‘very short’ takeoff and landing operation; however, the aircraft cannot hover. Freewing has demonstrated the tilt-body concept as part of NASA’s UAV Technology for Remote Sensing Applications program, providing an especially stable UAV platform for sensitive instruments.

The Manta variant was developed jointly by Freewing and Veda Inc. (now Veridian) for the Navy’s VLAR program. Freewing has also teamed with Matra BAe (now BAE SYSTEMS) to develop the MARVEL, aimed at the European Naval market, with the goal of operating from the helipad of a French La Fayette class frigate. Several schemes are being considered to capture the UAV upon landing, including spring loaded clamps on the landing gear that would grip a grid in the ship’s deck, or an inflatable airbag covered with Velcro which would be flown at a special mat, where it would stick until the crew could properly secure it.
 

Also involved with the Navy VTOL UAV demonstrations in 1998, the Vigilante began as an optionally piloted vehicle (OPV) that could be flown in three modes: manned, remote pilot, or intelligent autopilot/mission control system. Developed jointly by SAIC (Science Applications International Corporation) and ATI (Advanced Technologies Inc.), the Vigilante is based on the Ultrasport Model 496 experimental helicopter kit (manufactured by ATI’s American Sportscopter division), a 2-seater with a Hirth 95 hp engine and a useful load of 590 lb. Originally created for the Ballistic Missile Defense Organization (BMDO) and Jet Propulsion Laboratory (JPL) to provide a stable, unmanned platform for an optical camera to monitor anti-ballistic missile tests, the airframe known as Vigilante 496 has since been modified for Navy requirements.

After abandoning the land-based Navy trials of the Vigilante 496 in 1998 due to flight control system problems, ATI and SAIC took the aircraft back to the design stage in an effort to overcome these problems and compete for the recent VTUAV contract. The new Vigilante 500 model includes an improved flight control system, a new airframe with a smaller streamlined shell for reduced drag, improved efficiency and reduced radar cross section. A heavy fuel engine required for Navy use was also planned, and the aircraft redesignated the Vigilante 600. The Vigilante was projected to have an endurance of 16 hours, a radius of operation at 500 nm, and a top speed of 135 kt. SAIC chose not to submit a proposal for the VTUAV competition, citing what they considered to be a "punitive" contract fee arrangement. However, the Vigilante will be used as the flight demonstration vehicle for a recently awarded NASA Revolutionary Concepts (REVCON) program investigating the feasibility of "swashplateless" helicopter flight.
 

Developed at Northrop Grumman’s recently acquired Ryan Aeronautical Center in San Diego, the Model 379 is a derivative of the Model 330SP three/four-place manned helicopter built by Schweizer Aircraft Corporation of Big Flats, New York. A relative latecomer to the VTUAV program, NG-RAC took a similar approach to SAIC’s Vigilante (see below) by adapting a proven manned vehicle to autonomous use. Believing that the Navy’s decision would be based on low risk and low life-cycle cost (a recent point of emphasis in DoD acquisition programs), Ryan selected an "off-the-shelf" helicopter to take advantage of the proven engine, airframe, rotating parts and drive train already in production and with spares already on the shelf. Only the fuselage and fuel tanks are new in the Model 379, with the fuselage streamlined to improve air speed, and the tanks enlarged to meet endurance requirements. The on-board communications systems and avionics software architecture also use proven components based heavily on systems developed for Ryan’s long range Global Hawk UAV.

The Model 379, now known as the Fire Scout, has a maximum speed of 115 kt, but is expected to increase to 150 kt with further streamlining. The streamlined aircraft would exceed the Navy’s threshold value of 135 kt for maximum cruise speed, yet fall well short of its objective speed of 200 kt. Power for the 27 ft diameter main rotor is provided by a 420 shp Rolls-Royce Allison 250-C20W turboshaft engine. Maximum gross takeoff weight is almost 300 lb higher than the 330SP at 2,550 lb, with an empty weight of 1,457 lb and a mission fuel load of 793 lb.

Other members of Northrop’s team include Lockheed Martin Federal Systems (shipboard integration), L-3 Communications (communications gear), IAI Tamam (multi-mission optronic stabilized payload), Sierra Nevada (UAV Common Automated Recovery System) and Raytheon (tactical control station).
 
 

Kaman has a long history of droning helicopters, including the first successful remotely piloted helicopter, a modified HTK, flown in 1952. The K-MAX served as a "surrogate" UAV in 1998 for several Marines demonstrations, including the Limited Technical Assessment of the BURRO (Broad-area Unmanned Responsive Resupply Operations) concept, where it lifted loads of up to 6,000 lb, including a 4,500 lb HMMWV truck, and delivered them to multiple landing zones on shore using GPS guidance. Cargo pickups at sea were made from the deck of the Office of Naval Research’s SLICE vessel (shown above), at speeds of up to 28 kt. The Marines also used the K-MAX in a multi-role element in June 1999, demonstrating the potential for an automated artillery system. The K-MAX delivered a 6,000 lb Dragon Fire semi-autonomous mortar system into position, then loitered to act as a targeting platform through the use of a remotely operated camera and laser range finder.

The Kaman Aerospace Corporation has received two contracts from the U.S. Marines (a $4.2 million contract in July 1999, and a $2.7 million follow-on contract in May 2000) to demonstrate an unmanned version of its K-MAX medium-lift helicopter as part of the BURRO program. Kaman plans to fly the unmanned variant of the K-MAX in the June-July 2000 timeframe. Demonstrations of the unmanned resupply concept are scheduled for this autumn at the Marine Corps Air-Ground Combat Center in Twenty-Nine Palms, CA, featuring a fully automated BURRO able to autonomously navigate a pre-programmed course while carrying an external load.

The K-MAX is powered by a Lycoming T53-17A-1 turboshaft engine, flat rated to 1,350 shp. The two 48 ft diameter, intermeshing rotors support a maximum takeoff weight of 12,000 lb with a 6,000 lb maximum external load. Mission range is 300 nm with maximum fuel load.
 

In June 1998, Boeing and DARPA announced a three-year study and demonstration of its canard rotor/wing aircraft (CRW) concept, known as the Dragonfly, as part of the Advanced Air Vehicle (AAV) program. The CRW configuration was originally investigated in 1993 by McDonnell Douglas and NASA, including the determination of aerodynamic and controls performance in NASA Langley’s 14-by 22-ft Subsonic Wind Tunnel. Two CRW technology demonstrators will be designed, built and flown by 2001 to validate aerodynamic performance, stability and control, and command and control of the aircraft. The reaction-drive wing/rotor system combines the high speed (350 kt) and longer range (500 nm) of a fixed-wing aircraft with the flexibility of rotary-wing flight. The aircraft is propelled using a conventional turbofan engine, using a diverter valve to direct exhaust gas to the rotor tips during hover and transition. A reaction-drive rotor eliminates the need for an anti-torque system, drivetrain and transmission, reducing weight, complexity and maintenance costs. Boeing’s confidence in the reaction-drive system is based on Hughes’ experience with XH-17 and XV-9A in 1950s and 1960s. Missions envisioned for the aircraft include reconnaissance, communications and relay, logistics resupply, urban operations and delivery of lethal and non-lethal munitions in manned and unmanned variants. This type of aircraft could potentially give the Navy Predator-like (i.e. fixed wing) endurance with VTOL capability, allowing commanders at sea to operate organic RSTA UAV missions from any ship capable of helicopter operations.
 

Although several UAV and Micro Air Vehicle (MAV) concepts have used the Hummingbird moniker, the latest is a product of Frontier Systems. The VTOL UAV is the second aircraft being developed as part of the DARPA AAV program; a 30 month Advanced Technology Demonstration contract was awarded March 1998. First flight of the two planned A160 prototypes is expected in 2000, with continued flight testing and sensor integration in 2001. The goal is a stealthy surveillance rotorcraft capable of up to 48 hours endurance and an unrefueled range of more than 2,000 nm. The aircraft is to have a hingeless, rigid three-blade rotor with low tip speeds and low disk loading for increased endurance, and a smoothly contoured fuselage for low radar signature. The detailed design, fabrication and testing of the A160 concept will determine its reliability, maintainability and performance.

About the Author:

Dr. McKee works for Analytic Services, Inc. (ANSER), Arlington, VA in the Defense Systems Division. He holds a B.S. and a Ph.D. in aeronautical engineering from The Ohio State University, and was previously involved with advanced UAV programs at Aurora Flight Sciences, Manassas, VA.