High-Altitude Long Endurance (HALE) is the description of an air-borne vehicle which functions optimally at high-altitude (as high as 60,000 feet) and is capable of flights which last for considerable periods of time without recourse to landing.
The idea of HALE was acknowledged in technical papers as early as 1983, with A preliminary study of solar powered aircraft and associated power trains written by D.W. Hall, C.D. Fortenbach, E.V. Dimiceli and R.W. Parks (NASA CR-3699), the actual state of affairs within technology of a time during the 1970s, allowed for scientists to later consider the possibility of Long endurance flight as a conceivable inclusion to aviation of suborbital spacecraft. One of the first papers to explicitly mention Long Endurance is J.W.Youngblood, T.A. Talay & R.J. Pegg Design of Long Endurance Unmanned Airplanes Incorporating Solar and fuel cell propulsion, published 1984. An early paper which incorporates both high-altitude and long-endurance as the area of investigation, is M.D. Maughmer (University Pennsylvania State) and D.M. Somers (NASA Langley) Design and experimental results for a high-altitude, long-endurance airfoil. The authors state interest in development of such a craft lay in the need to fulfill communication relay missions, weather monitoring, and to obtain information for the targeting of cruise missiles. This paper had a publication within the year 1989.
The research paper, 2025, written by B.W. Carmichael (Colonel), and Majors, T.E. DeVine, R.J. Kaufman, P.E. Pence and R.E. Wilcox, and presented July 1996, foresaw routine HALE-UAV operations happening within the early 21st century. In contemplation of a future of the military, projected to 2025, the authors thought a HALE in flight for 24 hours. Long endurance ("long-loiter") is held synonymous with the concept of maintaining air occupation, "the ability to hold an adversary continuously at risk from lethal and non-lethal effects from the air".
G Frulla (Turin, Italy 2002) wrote a paper on very long endurance.
Lockheed-Martin have produced a HALE Demonstrator, which was the first of this type of craft. The HALE-D vehicle was launched during July the 27th 2011 to operate from a location which is higher than the jet-stream in a geostationary position. The HALE-D was to function as a surveillance platform, telecommunications relay, or a weather observer.
Armstrong Flight Research Center have a HALE known as Global Hawk. The craft was used in a year 2014 Airborne Tropical Tropopause Experiment. The craft was created and developed by Northrop Grumman. The capacity for Long-endurance for this craft is 24 hours operational time.
Altus II, (Latin: Altus meaning High) runs at heights of 18 kilometres and 288 metres (60,000 feet) plus, with endurance times of 24 hours approximately, with variations of capabilities of endurance dependent on the altitude of operation.
A design paper (Z. Goraj et al 2004) describes the HALE PW-114 craft, equipped with sensors to fly at a height of 20 kilometres for a duration of 40 hours.
RQ-3A DarkStar is a high-stealth oriented craft built to function optimally within highly defended areas, in order to make reconnaissance. The craft is intended to hover over targets for a period of time of at least eight hours, at heights of 13.716 kilometres (45,000 feet) and beyond.
Airbus Zephyr was designed to fly at a maximum height of altitude 21.336 kilometres (70 000 feet), and in a 2006 flight, was airborne for 80 hours, which was then was the longest flight made by a HALE vehicle. Model 7 holds the official long-endurance record for an UAV of 336 hours, 22 minutes and 8 seconds, a flight made from the 9th to the 23rd of July 2010.
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- B.W. Carmichael (Colonel), T.E. DeVine (Major), R.J. Kaufman, (Major) , P.E. Pence (Major), R.E. Wilcox (Major). Research Paper (PDF). published by The U.S. Air-force August 1996. Retrieved 2015-12-10.CS1 maint: multiple names: authors list (link)
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touched down at 1504 BST ... on Friday ... took off ... at 1440 BST (0640 local time) on Friday, 9 July
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