• Garth Calitz

Solar Drone Development

Though many people immediately associate unmanned drones with military use or some kind of dubious espionage activity, but they have incredible potential to be used in a wide variety of peaceful and scientific applications. In addition to delivering supplies to disaster-stricken areas, drones could be used to gather information about things like weather and wildlife.

Titan Aerospace Solara 50

Titan Aerospace is currently developing a drone named Solara 50 that is being hailed as an “atmospheric satellite” and has quite a lot to offer in terms of gathering scientific data. The drone will 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 it unobstructed access to the sun, which will power the 3,000 solar cells that cover its 50-meter-long (164 feet) wings. The solar cells will also charge lithium ion batteries stored inside the wing so it can fly at night, which means that this drone can fly uninterrupted for up to 5 years all while producing zero emissions.

The body of the drone is durable carbon fiber, and the 5-kilowatt electric motor will allow the aircraft to cruise at about 96 km/h (60 mph). Though the aircraft itself weighs only 160 kg (350 lbs), it will be able to carry 32 kg (70 lbs) worth of payload up into the stratosphere.

Solara 50 is completely self-piloted; able to take off, cruise, and land on its own. It will function much the same way as a satellite, though it will cost much less to launch. From the air, it would be able to track developing storms, migrating wildlife, vegetation patterns, and it would also have data communications capabilities; a feature that has caught the eye of the social media giant, Facebook.

Facebook would use the drones to bring the internet to the 5 billion people around the globe who aren’t online as part of the Internet.org initiative. They are interested in acquiring Titan Aerospace for an estimated $60 million. If it goes through, Facebook will launch 11,000 units to start, which would be used to connect rural regions in Africa to the rest of the world. This is a similar—yet more sophisticated—concept as Google’s Project Loon, which had the same internet connectivity goals in mind though it utilized weather balloons instead of precision-guided drones.

Caihong-T 4

The "Caihong-T 4" (CH-T4), built by the Chinese Academy of Aerospace Aerodynamics (CAAA), has a double-bodied fuselage, cranked wing, and twin tail. It's got a wingspan of 40 meters, which means its wider than a Boeing 737 jetliner. Despite the large size, it weighs between 880 and 1,100 pounds. It owes its lightness to its carbon fibre and plastic components.

In size and flight altitude, that's second place to only the NASA Helios Prototype, another solar-powered flying wing, which boasts a 246-foot wingspan, and a elevation of 96,863 feet. CAAA scientists told the China Daily that the CH-T4 has a flight time design goal of several months, needing only minimal human supervision.

Flying up to 65,000 feet means that the CH-T4 will fly above almost all cloud cover, so it will enjoy almost unlimited access to sunlight during its operations (during night, the CH-T4 will draw from onboard batteries to power its motors).

China's long-duration drone projects parallel work at both DARPA and tech companies like Facebook. For militaries, tech like this provides an excellent platform for surveillance missions against military and terrorist targets. It can utilize its high flight ceiling to maintain line-of-sight contact with over 400,000 square miles of ground and water. That's about the size of Egypt. For both militaries and tech firms, covering so much territory makes it an excellent data relay and communications node. This will allow the drone to replace or back up satellite communications, maintain coverage between distant aircraft and ships, or even provide broadband to rural Chinese households.

The NASA Centurion was modified into the Helios Prototype configuration by adding a sixth 41 feet (12 m) wing section and a fifth landing gear and systems pod, becoming the fourth configuration in the series of solar-powered flying wing demonstrator aircraft developed by AeroVironment under the ERAST project.

NASA's Helios Prototype

The larger wing on the Helios Prototype accommodated more solar arrays to provide adequate power for the sun-powered development flights that followed. The aircraft's maiden flight was on September 8, 1999.

The ERAST program had two goals when developing the Helios Prototype: 1) sustained flight at altitudes near 100,000 feet (30,000 m) and 2) endurance of at least 24 hours, including at least 14 of those hours above 50,000 feet (15,000 m). To this end, the Helios Prototype could be configured in two different ways. The first, designated HP01, focused on achieving the altitude goals and powered the aircraft with batteries and solar cells. The second configuration, HP03, optimized the aircraft for endurance, and used a combination of solar cells, storage batteries and a modified commercial hydrogen–air fuel cell system for power at night. In this configuration, the number of motors was reduced from 14 to ten.

Using the traditional incremental or stairstep approach to flight testing, the Helios Prototype was first flown in a series of battery-powered development flights in late 1999 to validate the longer wing's performance and the aircraft's handling qualities. Instrumentation that was used for the follow-on solar-powered altitude and endurance flights was also checked out and calibrated during the initial low-altitude flights at NASA Dryden.