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Solar-Powered Flight For 81 Hours: a New Endurance World Record
Hallie Siegel writes: A team of researchers from ETH Zurich have just set a new endurance record for solar powered flight of an unmanned autonomous aircraft, achieving over four days of solar-powered flight in a range of weather conditions. Being able to demonstrate more than 24 hours of endurance is important because overcast skies can inhibit recharging and poor weather or high winds can effect power consumption. Nice achievement for this class of aircraft.
This is yet another demonstration of the rapid advances taking place in both battery technologies and solar panel efficiency. A few years ago, I was not particularly optimistic about the medium term prospects for large scale replacement of coal, gas and nuclear power generation by solar. I am more hopeful today.
Google bought Titan Aerospace after their prototype flew for one solid year. In 2014. That was a drone... And then recently there was a 120 hour manned flight from Japan to Hawaii in a manned solar powered plane. They've flown about halfway around the world and plan on finishing the full round the world trip with the plane. 4 days flying time is not even notable at this point manned or drone. Airbus is already building and flying prototype 4 person consumer jets across the english channel.
moox. for a new generation.
Perhaps OP was thinking of what they promised (a 5-year flight), or perhaps my quick googling is insufficient... I was able to find a 14-day unmanned solar-powered flight in 2010 from Qinetiq's Zephyr craft.
Following the link to the article (I know, I know, this is slashdot, we don't do that here), there's an important qualifier missing from the summary; this is a record for an aircraft *in its class*. Specifically, that class is aircraft under 50 kg total mass. They do cite the Zephyr (now as an Airbus property) as the longest UAV flight, and Solar Impulse 2 as a longer flight by a (manned) solar airplane. It is also notably different than the Zephyr because it is a "low-altitude" vehicle. From one of the research papers on their website (OK, I realize this is getting out of hand... I mean, following the link is one thing, but doing a google search for the company involved???), it looks like they're staying below 1,000 meters. The Zephyr is intended to fly between about 60,000 and 70,000 feet, where winds are weaker and there is less drag. On the other hand, apparently this craft has an IR camera to help it find thermals that it can ride to help reduce the power requirements.
That said, given the additional requirements of transporting a human, I give the award for most impressive achievement to the Solar Impulse team. Their pilot outweighs not only the payload of the AtlantikSolar and Zephyr crafts (0.8 kg and 2.5 kg, respectively), but probably also the whole UAV itself (6.8 kg/15lb and 53kg/117lb, respectively - I'll assume that their pilots don't have a second job as a jockey). Add to that about 5 pounds of food and 7 pounds of water/drinks *per day*, plus some bottled oxygen so the pilot can breathe at 40,000 feet... And apparently the sensor and data downlink package from Solar Impulse consumes up to 50W - that's as much as the craft in this article uses for all its needs, including propulsion. There's a lot of stuff required to keep us silly humans alive.
I'll grant them that it's an impressive feat in a small package - but I still think the bigger package with the bigger payload (a human) is more impressive.