A revolutionary high flyer design which may well represent the future of aviation in the 21st century...

Initial customer:   Angel Technologies Corporation
Current status:   Northrop Grumman-owned experimental prototype

Type:  high-altitude communications relay prototype / high-altitude long-endurance testbed

Programs:  High Altitude Long Operation (HALO™), NASA ERAST, etc.

Powerplant: 2 x Williams FJ44-2E turbofans

First flight: 26 July 1998

The HALO-Proteus aircraft, named for the Greek god able to change its physical form at will, is a High Altitude Long Operation (HALO™) aircraft which sports a canard wing, an interchangeable center fuselage and twin fan jet engines. The Proteus is a tandem-wing design intended to carry payloads of up to 2,000 pounds to altitudes above 60,000 feet and to remain on station up to 14 hours. It was designed to provide the commercial communication industry a reliable alternative infrastructure that can be deployed instantly, even when terrestrial infrastructure is missing or incomplete. Applications that can benefit most from the availability of airborne deployment are the broadband data services in developed countries and wireless telephony services in the developing world.

Angel Technologies Corporation (now is a privately-held wireless communications company located in Saint Louis, Mo., which uses proprietary High Altitude Long Operation (HALO™) aircraft to deliver services worldwide. Augmenting terrestrial towers and orbiting satellites, Angel's HALO aircraft can fly fixed patterns in the stratosphere over major cities to deliver metropolitan wireless services at lower cost, with increased flexibility and improved quality of service. Teamed with corporate partners (including Raytheon), Angel plans to deliver a variety of fixed and mobile wireless services including voice, data and video. The HALO Network could enable individual consumers and businesses to send and receive data at multi-megabit per second rates.

Angel Technologies Corporation and its partners are creating a wireless broadband "super-metropolitan area" network to interconnect tens to hundreds of thousands of subscribers at multi-megabit per second data rates. The HALO™ Network will offer ubiquitous access and dedicated point-to-point connections throughout a "footprint" 50 to 75 miles in diameter. A piloted, FAA-certified High Altitude Long Operation (HALO) aircraft will provide the "hub" of the network. Operating continuously over each market, the HALO aircraft will create a "Cone of Commerce™" in which prospective customers will access broadband services irrespective of their locations. HALO Networks will be financed and deployed to select markets, on a city-by-city basis, around the world.

The HALO Network will provide consumers with a broadband digital utility for accessing multimedia services, the Internet, and entertainment services. The network equipment at the subscriber's premise will be standards-based and employ a user interface as simple as today’s typical consumer modem. Consumers will be able to access video, data, and the Internet at rates ranging from 1 to 5 Mbps. Angel will offer higher data rates as the broadband market matures. Plans have also been made to replicate this network over metropolitan centers throughout the world.

Equipped with suitable payloads, Scaled Composites's HALO-Proteus aircraft was conceived to deliver high-capacity, high-quality services while positioned 10 miles above metropolitan regions. The HALO-Proteus aircraft with its payload would create a cellular pattern covering an area comparable to several hundred cellular towers. Burt Rutan, president of Scaled Composites and designer of the aircraft, declared in the company's Inaugural Flight Press Release on September 22, 1998: "Given the business requirements proposed by Angel, we designed an aircraft for economical and reliable access to the stratosphere. The Proteus has long thin wings like our Voyager round-the-world plane, but the similarity stops there. The Proteus’ strong structure can withstand more G-force than a typical business jet. It has been designed from the start to be robust and reliable."

On October 25 and 27, 2000, the HALO Proteus Aircraft set 3 world altitude records. The three records were peak altitude (62,786 feet), sustained altitude in horizontal flight (61,919 feet), and peak altitude (of 55,878 feet) with a 1000-kg payload. These altitudes significantly exceeded the existing records in Class C-1.E, Group III. "I’ve been around aircraft of all kinds. The Proteus is truly unique," commented Allan McArtor, former FAA Administrator and senior executive at Federal Express. "The HALO-Proteus has the potential to open a whole new segment of aviation, the carriage of data instead of people or cargo."

Although Scaled Composites (then affiliated to the Wyman-Gordon company) produced the Proteus aircraft as a piloted aircraft primarily designed for commercial telecommunications relay purposes, it is also capable of completing many of NASA's ERAST missions, and has therefore been tested extensively in that purpose. Scaled Composites' Proteus joined the ERAST stable as an "optionally piloted" technology demonstration aircraft. First flown in mid-1998, the twin turbofan-engine aircraft is larger and heavier than other consumable-fuel aircraft involved in ERAST. Development of the Proteus under ERAST focused on supporting development of the aircraft's flight control system to allow it to be an "optionally piloted" aircraft, capable of being flown either by an onboard pilot or autonomously. Proteus was also utilized to validate many of the technologies required for UAVs, including over-the-horizon command and control communications.

Scaled Composites modified the aircraft to achieve some level of remote piloting capability. In addition to this, "over-the-horizon" communications capabilities were successfully installed and tested on the Proteus. These capabilities were used to communicate with the aircraft when it was ferried to and from the 1999 Paris Air Show. This communications link uses satellites as a relay to talk to either the pilot or to the on-board computer. In 2002, Proteus was the central focus of a flight demonstration of cooperative transponder-based "detect, see and avoid" (DSA) collision-avoidance systems while being operated as a surrogate UAV. A similar demonstration employing a radar device on the Proteus with non-cooperative (non-transponder equipped) target aircraft was made in early 2003.

Population: 1 [N281PR]

Wingspan: 16.7/23.7 m
Length: 17.16 m
Start mass: 6700 kg
Ceiling: 18000 m
Payload: 900 kg

Crew/passengers: 2 crew, 1 passenger

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