High-altitude platforms (HAPs) are aircraft, usually unmanned airships or airplanes positioned above 20 km, in the stratosphere, in order to compose a telecommunications network or perform remote sensing. Aerospace companies have been trying for years to create a solar-powered plane that can fly at high altitudes for years at a time, and can provide broadband communication services. These drones fly at an altitude of over 19,000 meters (65,000 feet) where there is little air traffic and above most weather that could impede its travels. Flying at that height will also give them unobstructed access to the sun’s power, which is harnessed by solar cells covering their wings. The solar cells also charge lithium ion batteries stored inside the wing so they can fly at night, which means that these drone can fly uninterrupted for many years all while producing zero emissions.
The race has become intensified recently with companies like Facebook and Google, that are looking to expand their markets and find new Internet users in tropical regions like South Asia, Africa and Latin America. They could have many other uses, for example acting as a relay station for communications in emergencies such as natural disasters that have knocked out ground-based telephones and internet links. Civil applications could include pipeline, crop and forestry fire monitoring, fisheries protection and border control.
Prismatic and BAE Systems are developing a solar-powered UAV , PHASA-35 with the potential to fly without landing for up to a year. PHASA-35 is not the only project working on a solar-powered high-altitude UAV. Up to 2003 NASA flew a series of solar-powered UAVs, including the long endurance, high-altitude Helios. Google-owned Titan Aerospace also worked on the Solara 50 and Solara 60 solar-powered HALE UAVs which aimed to operate at 20km altitudes for up to five years but the project was ended in 2017. Boeing Phantom Works did development work up to 2012 on the SolarEagle which it claimed could fly for up to five years at 60,000ft. QinetiQ developed the Zephyr series of high altitude pseudo satellites (HAPS), a project that was taken over by Astrium in 2013 and the project now operates as part of Airbus. The Airbus Zephyr, now being built at Farnborough for the UK MoD, still holds the world record for endurance with two weeks aloft.
Internet giant Facebook too has flown its own solar-powered Aquila high altitude UAV. Two other examples include the Russian LA-252, which can fly up to an altitude of 13 miles for a number of days and the Chinese-built Caihong T which is reported to be able to fly at heights of up to 20km but only during daylight hours.
Military is also turning to solar powered stratospheric drones for communications and persistent, wide area, real time Intelligence, Surveillance, and Reconnaissance (ISR). Military has been employing various platforms like Balloons, Aerostats, Airships, Satellites, and UAVs for satisfying the requirement for persistent, real time and wide area coverage of battle space. The helium powered Airships have safety issues, while satellites have been expensive to launch. For remote sensing, HAPs have as an important advantage over satellites, mainly the low orbit ones, the ability to remain continuously over an area for very long periods (persistence). Another advantage is to permit better resolution images, because they are closer to the covered areas .
Chinese-developed drone is undergoing testing appears to have overcome such difficulties, marking a significant step towards China’s ambitions of exploiting near space for purposes of military intelligence. In June, China Aerospace Science and Technology Corporation flew a large, solar-powered drone at an altitude of 20,000 metres for 15 hours. The Caihong T4 aircraft, with a wing span of more than 45 metres, could be equipped with radar and communications equipment to provide early warning for Chinese military aircraft, according to state media reports. China has also flight tested “Ghost 6”, designed by North West Polytechnic University (NWPU), wherein it flew for 19 hours and 34 minutes at 7000 meters, landing autonomously on the dirt road on 28th August. The objective of the test was to probably verify the aerodynamic configuration of the vehicle and its energy management efficiency in lower natural lighting of Autumn/ Winter seasons, which is only one third that of in the summer.
The Joint Forces Command’s high altitude pseudo-satellite (HAPS) operational concept demonstrator aircraft has beaten the world flight endurance record by remaining airborne for more than 25 days without refuelling. The Zephyr-S unmanned aerial vehicle (UAV) has the capability to operate in the stratosphere at an average altitude of 70,000ft while carrying out a wide range of operations, including land and maritime surveillance, and a number of communication tasks.
China to fly solar drone to near space
Competition among drone makers in China is heating up, with several manufacturers vying to operate the nation’s first solar-powered drone. State-owned space and aviation conglomerate China Aerospace Science and Industry Corp (CASIC) now reportedly enjoys a head start with its Feiyun (flying clouds).
A technician with the company told Xinhua of “satisfactory advances” toward building a solar-powered, drone-based, near-space network for long-distance emergency telecommunications and Internet services. CASIC conducted more than 100 test flights of its solar drone prototype last year, paving the way for larger trials for its Feiyun long-range solar-powered aircraft series beginning in 2020, when a drone network is expected to make a first-ever cross-China journey.
The Feiyun solar drone employs photovoltaic cells and powerful electric motors mounted on its monoplane airframe made from ultralight composite materials. The entire aircraft reportedly weighs less than a ton, even though its wingspan is said to be comparable with that of commercial wide-body passenger jets like the Boeing 777. More than 10,000 photovoltaic cells on the drone’s upper wing surfaces generate electricity to power its motors while charging lithium-sulfur batteries to power night flying.
Russian solar powered SOVA (Owl) atmospheric satellite drone
The solar powered SOVA (Owl) atmospheric satellite drone is a collaborative effort of the Tyber Company and the Advanced Research Foundation (ARF) has a nine-meter wingspan, yet weighs only 12kg. The Advanced Research Foundation (ARF), established in fall 2012, is viewed as Russia’s analogue of the US’s DARPA, conducting some leading defense industry research.
The flying wing (fixed-wing with no tail or discernible fuselage) unmanned aircraft covered with solar panels and driven by three propellers has already climbed to a 9km altitude and spent over two days up in the air. SOVA’s elastic hull is twists, bends – and restores the original form to handle turbulence and gusts of wind. The drone carries accumulators to store energy to continue flight in the dark hours, cameras, altimeter, transmitter, receiver and other sensors enabling operator to monitor and direct its flight.
The second prototype, with a wingspan of 28 meters, is expected to be able to reach altitudes of 20km. The SOVA project aims at developing a family of drones for super long-endurance missions, to be operated throughout Russia and even in harsh conditions above the Arctic Circle (66.5°N).
Inexpensive monitoring of the vast uninhabited territories in northerly latitude and providing telecommunication services to constantly growing number of consumers have been mentioned among top priority tasks for SOVA atmospheric satellite drones. So far communications in the Arctic area have been established using space satellites, but this kind of communication is expensive and not always effective, particularly for real-time monitoring needs.
Airbus builds drones that fly 90 days non-stop for UK military
The development of Zephyr solar high-altitude UAV family began in 2001 . In July 2010, the Zephyr 7 , developed by the British company QinetiQ, established the current flight endurance record of 336 hours and 21 minutes (14 days), flying at about 18 km altitude on a US Army test range, in Yuma, Arizona (Amos 2010). The Zephyr 7, with 23 m wingspan, 55 kg weight, and 5 kg payload, has two propellers driven by electric motors and uses the energy from solar panels during the day and lithium-sulfur batteries at night. Airbus is building unmanned “Zephyrs” that flying at heights of about 70,000 feet at speeds of 20mph will be used to demonstrate technology that could ultimately see the British military fielding reconnaissance aircraft that could monitor targets for months at a time.
Airbus is currently working on Zephyr 8, having Wingspan of 28 meters, able to cruise at approximately 21,000 meters with speed of 55km/h while carrying a payload of 5-10 kg. The amorphous silicon PV and lithium-sulfur (Zephyr 7) Batteries power 2x 450 Watt electric motors. Zephyr S version (single-tail), formerly Zephyr 8, is now in production with the first order having been made by the United Kingdom Ministry of Defense. Britain’s Ministry of Defense (MoD) will acquire three solar-powered drones, the drone’s manufacturer said.
Zephyr is a High Altitude Pseudo Satellite (HAPS) UAV running exclusively on solar power. The UAV has all the advantages of an aircraft and satellite combined: it can be re-used and has a wide coverage due to its flexibility in location. At the same time it’s capable of taking on similar tasks as satellites: it can fly at high altitudes, perform similar applications and is reliable.
Flying at 20km altitude at a fixed location, Zephyr can see over 400km to the horizon and provide persistent high resolution imagery and high bandwidth communications to areas in excess of 1,000 km2. Airbus wants the drone to fly for 100 days without landing (its currently record is 25 days without refuelling) and travel up to 1,000 nautical miles per day. It weighs 75kg, but can support a payload up to five times its own weight.
Airbus is targeting several applications with its Zephyr drone, including Full HD imaging, thermal imaging, the creation of temporary communications networks and emergency services support. The earlier trials included the operation of a number of electro-optical and infrared imaging payloads and the real time transmission of images and video from the air vehicle in flight. The flight trials also included the air vehicle being used as a communications relay platform and demonstrated the capability to provide beyond line of sight communications between radio handsets at long distances in mountainous terrain.
Zephyr can produce very accurate pictures of the Earth – down to 15cm resolution – using small, lightweight cameras. And, of course, these pictures can be produced all the time, even as video or, using infrared technology, at night. Radar systems are also in development to allow Zephyr to provide 24/7, all weather surveillance,
Airbus said the system could provide non-stop surveillance of targets because it is able to operate two of the drones together, meaning that one can hand over to another with the aircraft being able to “talk” to each other, creating seamless coverage. It can execute wide range missions including specific target monitoring, anti-piracy efforts, route monitoring, counter-IED, border security and local area security.
BAE Systems and Prismatic, plan to test the Persistent High Altitude Solar Aircraft (Phasa-35) drone in 2019.
In May 2018 defence manufacturer BAE Systems announced that it was working on a joint project with UK aerospace technology company Prismatic to develop a high altitude long endurance (HALE) solar-powered electric unmanned aerial vehicle (UAV). Called PHASA-35 (short for 35m wingspan Persistent High Altitude Solar Aircraft) the new design will have the potential to fly for up to a year without landing.
Named PHASE-8, the quarter scale Reynolds scale test vehicle was designed to replicate at low levels the behaviour and performance of a larger UAV flying at an altitude at 65,000ft. Weighing less than 12kg, the PHASE-8 UAV has a wing span of 8.75m. The vehicle can be transported in a 2.4m transit container, hand-launched and recovered from the ground. Fitted with Prismatic’s PHASE power system, the demonstrator could fly for up to eight hours on batteries or for several days using solar power and rechargeable batteries.
PHASE-8 was flown on 75min test flight December 2017 followed by a two hour flight in January. The fully instrumented maiden flight enabled Prismatic to check the basic stability of the vehicle, tune the auto-pilot and run a number of tests to begin validating its performance. The subsequent January test flight included unpowered glides at different airspeeds, flight power and total energy usage. Although the PHASE-8 is a valid UAV design in its own right, its main purpose is to validate and tune the aerodynamic behaviour and future flight performance of the PHASA-35.
BAE and Prismatic are planning to build two examples of the PHASA-35. The 35m wingspan HALE UAVs will be built from carbon fibre and weigh a total of only 150kg each. The aircraft will be fitted with long life charging and storage-efficient batteries and an array of ultra-lightweight solar cells which, together with a 15kg payload, will weigh around half the mass of the aircraft.
The UAV would then will take approximately one day to climb to an altitude that would vary dependent on the weather but would be in the region of 55,000-70,000ft. Once it was at altitude, the PHASA-35 would then fly to its desired location. To enable the vehicle to remain stable and on station the cruise speed will be around 50kt. Control of the vehicle could be either from a remote operator or autonomous flight. BAE says that the flight control system fitted to both the PHASE-8 and PHASA-35 will have the ability to undertake both piloted and autonomous flight control.
The combination of lightweight construction, stable aerodynamic airframe and solar-powered batteries of the PHASA-35 will enable it to fly not just to high altitudes but also for long periods of time, potentially for up to a year before it needed to land for maintenance on items such as the flight controls and motor. BAE and Prismatic are confident that their design is more advanced than other competitors. “The aircraft can stay above the winds, maintaining position at all times of day even in the middle of winter,” commented Prismatic MD, Paul Brooks. “This is what all previous HALE UAVs have failed to accomplish and what must be assured if solar HALEs are to deliver the services that are so important to our customers.”
“Customer demands will dictate the payload specifics,” said a BAE spokesperson. “However, the technology would offer a year-round, low cost persistent service for a wide range of needs. This could include a whole host of commercial applications, including communications to remote areas, environmental surveillance, disaster relief, humanitarian support, border protection and maritime surveillance. HALE UAVs also promise significant advantages for UK armed forces and allies, as well as a significantly cheaper alternative to conventional satellite technology, such as extending GPS coverage to desolate areas and optical imaging purposes.
Facebook is ending Aquila, its drone-delivered internet project
The company is developing different technologies that are suitable for any region worldwide: Connectivity Labs believes that satellites will be most suitable for remote places with low population living over wide areas. Internet can be beamed down from multiple low orbit satellites, providing a continuous coverage. For the more densely populated areas such as towns, villages and suburb areas, Connectivity Labs will utilize high altitude solar powered drones (UAV’s). These PV powered drones will circle at 20,000 meters altitude, well above commercial airlines, away from disturbing weather, and will beam down high speed internet using laser communications.
The Aquila UAV, being developed by Facebook, is a flying wing with a wingspan of 42 m and a total weight of about 400 kg. The Aquila will fly between 18 and 27 km altitude, for a period of 3 months. Aquila is being designed with a goal to beam internet signal to people within a 60-mile communications diameter for up to 90 days at a time. The solar-powered drone has a wingspan of 42 m (138 ft), which is greater than that of a Boeing 737, Built with a carbon fiber frame it weighs around a third as much as an electric car and at cruising speed will consume only 5,000 watts – the same amount as three hair dryers, or a high-end microwave.
The aircraft has four propellers driven by electric motors, with power supplied by solar cells during the day and rechargeable batteries at night. It will be taken to the stratosphere by a helium balloon. The Aquila drones lack the standard landing gear that aircraft typically have as part of an effort to reduce weight. Instead, they are intended to land on specially designed kevlar pads.
It is expected the use of a laser connection to form a high-speed communications network. In case of obstruction by clouds, it will be used a radio connection with some reduction in data rate. A 1:10 scalemodel conducted flight tests in March 2014, in the UK
The project, which started in 2014, faced significant difficulties getting off the ground, which Facebook’s statement concedes “has involved a lot of trial and error.” The first test flight in Arizona in June 2016 launched and flew as expected, though turbulence before touchdown resulted in the drone landing short of the runway and receiving damage to the right wing in the process. A second test flight of a different model drone in May 2017, did not crash, though apparently suffered dings during landing, according to a post by Gomez at the time. Both Aquila test flights in Arizona faced difficulties during the landing phase, which caused varying degrees of damage to the drones. Facebook has suspended its internet via Drone experiment Aquila in an announcement posted to Facebook Code .
Google wants to beam 5G internet using solar-powered drones
Project Loon, from Google, started in 2012 and has the objective to create a network of stratospheric balloons to provide Internet access in remote areas. Project Loon is a network of balloons traveling on the edge of space, designed to connect people in rural and remote areas, help fill coverage gaps, and bring people back online after disasters, says Google.
Project Loon balloons travel approximately 20 km above the Earth’s surface in the stratosphere. Each balloon is of the superpressure type with 15 m diameter. Winds in the stratosphere are stratified, and each layer of wind varies in speed and direction. Project Loon uses software algorithms to determine where its balloons need to go, then moves each one into a layer of wind blowing in the right direction. The altitude control is performed by adding or removing air inside the balloon, with the use of a fan. With this, it is possible to select altitudes where the wind is in a convenient direction. By moving with the wind, the balloons can be arranged to form one large communications network.
In a secretive project codenamed SkyBender, the technology giant built several prototype transceivers at the isolated spaceport last summer, and is testing them with multiple drones, according to documents obtained under public records laws. Project SkyBender is using drones to experiment with millimetre-wave radio transmissions, one of the technologies that could underpin next generation 5G wireless internet access. High frequency millimetre waves can theoretically transmit gigabits of data every second, up to 40 times more than today’s 4G LTE systems. Google ultimately envisages thousands of high altitude “self-flying aircraft” delivering internet access around the world.
The huge advantage of millimetre wave is access to new spectrum because the existing cellphone spectrum is overcrowded. It’s packed and there’s nowhere else to go,” says Jacques Rudell, a professor of electrical engineering at the University of Washington in Seattle and specialist in this technology. Google is not the first organisation to work with drones and millimetre wave technology. In 2014, Darpa, the research arm of the US military, announced a program called Mobile Hotspots to make a fleet of drones that could provide one gigabit per second communications for troops operating in remote areas.
Titan’s Solara’s “Atmospheric Satellite”
Google’s Project SkyBender is currently using an “Optionally Piloted Aircraft (OPA)” called Centaur and a solar-powered drone called Solara 50 made by Titan Aerospace, which the tech giant acquired in 2014. Benefits of using OPA is, it can be used as Unmanned Ariel Vehicle (UAV) or as Manned aircraft.Titan Aerospace built high-altitude solar-powered drones with wingspans of up to 50 meters.
Titan Aerospace, is developing the SOLARA 50; with a 50 m (164 feet) wingspan that will reach altitude of 65,000 feet and stay aloft for five years at a time while carrying a payload of 70 pounds. The next design, the Solara 60, will carry up to 250 pounds. On May Day 2015, a Google-owned drone crashed shortly after takeoff somewhere in the sands east of Albuquerque.
The Solara by Titan Aerospace with a projected cost of less than $10 million, it will be a cheaper, retrievable alternative to conventional satellites. The payload-agnostic solar UAV platform capable of being deployed in any domain. The communications range of line of sight (LOS) radios are inherently limited and readily affected by the operational environment, mountainous regions being the most prevalent example. These communication ranges can be easily and affordable extended to BLOS (Beyond Line of Sight) communications using small, low cost radio repeaters and specialty communication equipment mounted on the SOLARA platform. Forest Fires are a global concern and the cost for combating these fires can range in the million, even billions of dollars. IT is also planned to be used as a key tool in the battle against forest fires in the process of fire monitoring.
Solara aircraft uses batteries charged from solar panels to power flight at night and provide about 100 watts of power to the aircraft’s payload, as well. It is launched by catapult and can land (when it has to) by skidding on its Kevlar-coated underside. Unlike the giant flying-wing configurations of the Helios and Zephyr, which had large numbers of propellers, the Solara has a single, high-efficiency motor. As the drone uses lithium ion batteries, rather than fuel cells, precision battery management system are used to ensure voltage and thermal thresholds are maintained in the subzero atmosphere. The drone will use silicon-based solar arrays formed into the outer wing structure, providing a multi-functional structural and power generating and structural strength.
According to Titan Aerospace, the platform maintains efficient energy harvesting even when the sun is low on the horizon, employing its high efficiency solar array positioned on horizontal wings and tail, slanted wing tips and vertical tail. To further conserve energy, the platforms use a distributed Maximum Point Power Tracking system, dynamically maintaining optimal voltage across the entire array at various solar insolation and incidence levels.
In theory, a solar-powered drone capable of withstanding long flights at high altitude—in what Titan executives call the “sweet spot” in the Earth’s atmosphere between 60,000 and 70,000 feet, above nearly all weather patterns in a zone where winds are typically less than 5 knots (5.75 miles/hour)—would be able to perform tasks usually reserved for satellites at a much lower cost.
For example, during a presentation by Titan at AVUSA, a company spokesperson compared using a satellite for multispectral Earth imagery—say, like Landsat’s—to using an atmospheric satellite. A drone could be put up quickly, for much less initial capital. At the same time, it would provide targeted imagery at a cost of less than $5 per square kilometer—versus $35 per square kilometer from a satellite—while still offering the large area of coverage of a satellite
Boeing and DARPA’s Solar Eagle
The Very high altitude, Ultra endurance, Loitering Theatre Unmanned Reconnaissance Element (Vulture) Program, coordinated by DARPA, had the purpose of developing a highaltitude airplane with ability to remain in flight for 5 years, with a payload of 454 kg, which consume 5kW. This platform would be employed in Intelligence, Surveillance and Reconnaissance (ISR) and communication missions
It was designed to cruise at altitudes of 60,000 to 90,000 feet with a thousand-pound payload at a speed of 70 to 80 knots while performing communications, intelligence, surveillance and reconnaissance missions. The solar-electric-powered drone, with 400-foot wings span carrying solar panel arrays, will be able to sustain the drone aloft in the stratosphere for at least five years. This project was canceled in 2012.
During the day, the solar power generation is used to power the aircraft and excess solar power generation is converted to hydrogen by the fuel cells as they operate in electrolysis mode. At night, the fuel cells run in fuel cell mode, converting the stored hydrogen to power. The aircraft was designed with solar arrays attached to its plastic skin, covering more than 50 percent of its surface. Highly efficient electrical motors and propellers and a high aspect-ratio wing, similar to those used in gliders, will all contribute for increased solar power and improved aerodynamic performance. Similar to satellites, the platform will be designed to be a “zero-maintenance, launch-and-leave” UAV, Boeing’s Pat O’Neil said.
According to DARPA energy management technologies – solar collection (photovoltaic) and fuel cells (energy storage systems) are vital for enabling ultra-persistent high-altitude, long-endurance (HALE) flights lasting multiple years. Solid Oxide Fuel Cell (SOFC) based energy storage systems have the potential to provide unprecedented round trip energy efficiency as the storage application of the technology is further developed.
A report from TMR estimates, the global high altitude platforms market valued at US$2.30 bn in 2014 and is expected to attain a valuation of US$4.77 bn in 2023. The market is expected to expand with a CAGR of about 8.7% over the forecast period from 2015 to 2023.
High altitude platforms (HAPs) are typically deployed in the stratosphere layers – more than 50,000 feet – for the applications such as communication, surveillance systems, and navigation. The high altitude platforms market is gaining traction due to growing advancement in the system for competitive advantages of HAPs over the satellite systems. The HAPs offers the advantages in the lowering cost of maintenance than satellite systems, easy and convenient maintenance, and installation in less time. In addition, growing investment and adoption of HAPs by numerous governments such as the US, India, China, and Israel are bolstering the growth of the high altitude platforms market.
A major factor contributing to the high demand in the high altitude platform market are the operational advantages over coverage area, manufacturing and repair costs as compared to conventional communication systems such as satellites and communication towers. These provide massive cost-savings in manufacturing, testing, and maintenance as compared to satellite systems.
The application of High Altitude Platform (HAP) Market can extensively aid in the reduction of crime, terrorism, contraband smuggling, and human trafficking owing to which countries are increasing their military and public safety spending to support the advancements of such technologies. For instance, India increased their military budget by 6% since last year and is anticipated to increase the spending in the coming years.
The increased demand for telecommunication services in rural and underserved locations is largely supported by government push for the development of the High Altitude Platform (HAP) Market. For instance, the application of High Altitude Platforms Mobile Robotic Telesurgery (HAPsMRT) was developed specifically by AeroVironment, Inc. for usage by the U.S. Army. These stations aid medical personnel to implement complex surgeries without latency issues in data packet transfers.
Rapid growth of the industrial and commercial sector in the South-East Asian regions due to low cost, high abundance of raw materials and skilled labour. Foreign players are increasing outsourced activities which cannot function without the availability of high-speed broadband communication services. Furthermore, there is also a notable increase in the reliance of the general population for a large scale of day-to-day operations such as e-learning, payments, gaming, among others fuelling the demand for the high-speed internet solutions via the HAP market.
Segmentation of the High Altitude Platform (HAP) Market by UAVs is anticipated to dominate during the forecast timespan owing to their applications in the defense sector. These systems can be designed to rely solely on solar powered technologies which is anticipated to cause large savings in term of fuel costs and reduce the CO2 emissions.