For example, the social media network, Facebook, recently tested its drone, Aquila, which has unusual specifications. The unmanned drone is very large, very light and very slow. It will fly at very high altitudes for weeks, powered by solar energy. The purpose: providing internet access. Lasers will transmit data in places where it is hard to provide internet access through conventional means.
The Aquila is made of lightweight carbon fibre and looks like a boomerang. It has a 29-metre wingspan, which is almost as much as a Boeing 737. But a 737 weighs over 52 tonnes; Aquila weighs under 400 kg (1 tonne=1,000 kg). Aquila will fly at speeds ranging from 40 km per hour to 130 kmph.
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It will sit above the clouds and weather, aloft at between 18,000 metres and 28,000 metres. This will help it tap solar energy uninterrupted, during the daylight hours. That solar energy will be stored in lightweight batteries and used at night.
The plane will fly for 90 days at a time, in circles of 50 km radius. It will use lasers and optical transceivers to transfer data at high speed to conventional mobile towers, which hook to smartphones. The energy consumption on the first flight was 2 Kw - as much as a hair dryer. When everything is working, the system will consume 5 Kw - as much as a microwave.
A lot of technical stuff needs to be ironed out even though the first test flight was successful (with one minor structural issue). Facebook plans a large fleet and it is hoping that net access this way will be more cost-effective than laying optical fibre.
Project Loon is an Alphabet project that also looks to provide cost-effective net access from the sky. But Loon intends to use balloons. Many test flights have happened. Loon is run by Alphabet subsidiary X (formerly Google X).
The Loon concept is to create a network of balloons floating at high altitudes and communicating to each other. The Loon balloons will provide an aerial high-altitude mobile network. Ground-to-air communication can be established via antennae on top of buildings. The aerial loon network will use LTE (4G) technology. It passes on data from balloon to balloon until a balloon connects to a normal Internet Service Provider using conventional wired or mobile access.
The record for continuous drone flight is just 14 days. Facebook has hired one of the engineers responsible for designing that record-breaking drone but Aquila needs to design for 7X that capability. However, balloons have often stayed aloft for over six months at a time. The current record is 187 days. A helium-filled balloon is lighter than air and could, in theory, stay up indefinitely.
The difficulties for ballooners lie in terms of powered flight and guidance. Loon will manipulate buoyancy to get the ideal height. There have been multiple test flights in many parts of the world. The balloons are said to have been made of different materials including highly flexible latex and rubber variants.
The balloons are 12 metres tall, fully inflated, and about 15 metres in circumference at their widest. The variable buoyancy comes from a pumping system that can pump in or release air. Solar panels, along with storage batteries, provide power. There is also a parachute to allow for a soft landing. There have been quite a few crashes however, and nobody outside Alphabet really knows how much has been invested so far in Loon.
Meanwhile, Hybrid Air Vehicles has just announced the successful test of what it claims will be the world's largest flying vessel. The Airlander 10 is a helium-filled airship that's 92 metres long (longer than the A380). It can be manned or unmanned. It is designed to stay aloft for five days and to carry a payload of up to 10,000 kg. One killer app: Airlander 10 can take off or land anywhere, including on water. This could find a lot of uses, including providing freight and passenger services to areas without airports.