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Following the work of HAPP, the CRC started work on their own version with the specific intent of making a communications platform. SHARP would use an 80 m diameter array of small parabolic dishes beaming 500 kW of power to the aircraft at 5.8 GHz frequency. At altitude, the beam was
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All of these studies culminated in the go-ahead to build an eighth-scale model of the proposed production SHARP vehicle that would be powered by two small electric motors. Power for takeoff would be provided by batteries, until it gained enough altitude that it could acquire the microwave beam and
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The economics of the system were attractive as a replacement for conventional satellites even in some large-area deployments. The CRC estimated the aircraft would cost about $ 100,000 each, and operate for $ 2 to $ 3 million a year. In contrast, just launching a satellite cost about $ 150 million.
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In the era before narrow-angle broadcasting from communications satellites was possible, television broadcasters faced the problem of only having technology that was suitable for greater metropolitan areas on the order of 100 km using conventional ground-mounted antennas, or large portions of
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Since a satellite was too high, and a terrestrial antenna too low, what was needed was a platform between the two, covering an area of a few hundred kilometers in radius – about the size of a
Canadian province. To do this the platform would have to fly at about 70,000 feet (21 km)
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Its maiden flight at the CRC took place on 17 September 1987. The system worked as expected, allowing launch by the batteries and capture by the 1 kW broadcaster shortly after takeoff. The initial 20-minute flight time was extended to over an hour by 5 October, and on the 6th a public
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also invested in the rectenna concept as part of their SPS work. This was tested in a ground-to-ground experiment in 1975, and as part of this they developed lightweight versions of the rectenna. In 1982, Brown and James Trimer (of NASA) announced a new version of the rectenna using
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Compared to SHARP, their MILAX (Microwave Lifted
Airplane Experiment) vehicle had two new design features. The rectenna on the aircraft was embedded in the wings and tail surfaces, eliminating the need for the separate antenna body. The broadcast antenna was based on an active
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Brown now had a system that could convert input power to microwaves with up to 70% efficiency and convert it back to electric power with 70% efficiency, resulting in an overall efficiency of about 50%. Brown looked for applications of the technology, working on both
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to provide energy from a ground station that powered electric motors spinning propellers to keep the aircraft aloft. The power was also used for the onboard electronics. SHARP could remain aloft indefinitely, and was intended to be used as a sort of low-altitude
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at the rear. This model was powered by a small gasoline engine and did not support a rectenna. The prototype demonstrated several aerodynamic problems, leading to an improved design that moved the horizontal stabilizer to the front of the aircraft into a
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Additionally, whereas a satellite of the era might have a lifetime of about 10 years, the aircraft could be periodically returned to the ground for servicing and upgrades, allowing it to operate indefinitely. They felt this would be attractive to
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at UTIAS studied aircraft configurations. In
September 1982 the Department of Communications gave the go-ahead to form a formal study group within the CRC, which studied rectenna design, leading to several patents on thin-film versions.
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The work was picked up in Japan at the Radio
Atmospheric Science Centre at Kyoto University. Starting immediately after the SHARP successes, Professor Hiroshi Matsumoto developed a similar vehicle, which flew on 29 August 1992.
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were another possibility. Of the available technologies, helicopters appeared to be too heavy, and aerostats, jokingly referred to as the "Gossamer
Hindenberg", were not well understood. An electrically powered
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the continent using satellites. Addressing the range between these two extremes normally required a network of repeater antennas, which were expensive given the smaller populations they normally served.
229:, allowing it to steer without physical movement. The system was tested by mounting the broadcast antenna on the back of a light truck, and driving it around while MILAX followed.
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focussed down to an area just larger than the aircraft. The aircraft normally flew in a circle about 2 km across, so the beam only needed to steer a few degrees.
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In spite of its success, SHARP research ended as part of a larger draw-down of the
Canadian research budgets. Ready for testing long-duration flights,
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In 1982 UTIAS built a prototype of the aircraft with a 1.3 meter high aspect-ratio wing mounted just above the fuselage, and a conventional
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In the years since the system was first proposed, advances in solar cells and battery technology have upset the initial calculations. The
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was awarded a contract to study the power requirements of a communications platform, while John F. Martin of Martin
Communications and
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Another beamed-power experiment in Japan was the ETHER project, which beamed 5.8 kW of power to a helium-inflated airship.
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demonstrated long-duration solar powered flight in a role essentially identical to SHARP. In the 2000s,
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techniques that reduced the weight by ten times. This made aircraft applications much more attractive.
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altitude. Aircraft and helicopters could do this, but only with short endurances. Super-high-altitude
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375:"Dual Polarization Microwave Power Transmission System for Microwave Propelled Airship Experiment"
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began development of such a vehicle specifically for the communications role, in this case as an
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self-power from that point on. The model, with a 4.5 meter wingspan, was built during 1987.
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The concept of using beamed power for aircraft propulsion was invented almost single-handedly by
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Gregg
Maryniak, "Status of international experimentation in wireless power transmission",
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attacked the SHARP aircraft while it was in storage, and the flights never took place.
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311:"Experimental Airborne Microwave Supported Platform, Final rept. Jun 1964-Apr 1965"
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appeared to be the best solution. At the time, a system using
388:"Google buys "atmospheric satellite" builder Titan Aerospace"
411:"Japanese Research for a Bright and Clean Energy from Space"
103:(HAPP) concept. This research went as far as flying a model
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demonstration was made for the
Minister of Communications,
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University of
Toronto Institute for Aerospace Studies
313:, RADC-TR-65-188, Rome Air Force Base, December 1965
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in the 1940s, Brown started work on improving their
201:. Their work won the "DiplĂ´me d'Honneur" from the
83:. He later worked with colleagues to develop the
336:"Communications satellites come down to Earth"
355:, Volume 56 Issue 1 (January 1996), pg. 87-91
272:, IEEE Global History Network, 29 August 2008
72:products. This led to the development of the
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427:Secret of Perpetual Flight? Beam-power Plane
76:, a simple, reliable and highly efficient
144:and batteries was considered too heavy.
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24:Stationary High Altitude Relay Platform
377:, Proceedings of ISAP '96, pg. 393-396
203:Fédération Aéronautique Internationale
189:testing at UTIAS during 1985 and 86.
38:(UTIAS) during the 1980s. SHARP used
32:Communications Research Centre Canada
26:, was an experimental aircraft using
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47:for smaller geographical areas.
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185:configuration. This underwent
101:High Altitude Powered Platform
1:
270:"William C. Brown: Biography"
107:using beamed power in 1965.
453:1980s experimental aircraft
16:1980s beamed-power aircraft
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91:power (the "rect"ifier).
413:, Kyoto University, 2003
45:communications satellite
448:1980s Canadian aircraft
74:crossed-field amplifier
34:(CRC) and built by the
28:beam-powered propulsion
342:, 26 May 1983, pg. 545
298:"An Overview of SHARP"
97:solar power satellites
268:Sheldon Hochheiser,
458:Canadian inventions
409:Hiroshi Matsumoto,
138:ultralight aircraft
373:Y. Fujino et al.,
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425:Arthur Fisher, "
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394:. 14 April 2014.
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30:designed by the
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241:Titan Aerospace
237:NASA Pathfinder
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170:James DeLaurier
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22:, short for
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209:After SHARP
187:wind tunnel
166:SED Systems
150:third world
142:solar cells
442:Categories
251:References
215:field mice
105:helicopter
56:Background
40:microwaves
205:in 1988.
152:markets.
133:aerostats
81:amplifier
78:microwave
70:magnetron
245:internet
164:In 1981
85:rectenna
66:Raytheon
247:relay.
51:History
183:canard
178:t-tail
256:Notes
156:SHARP
20:SHARP
111:NASA
429:",
444::
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338:,
327:^
277:^
89:DC
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