The solar-powered aircraft flying high in the atmosphere | BBC News

let me take you up up into the air up above the clouds above the weather above all the aircraft this is the stratosphere a place yet to be conquered by humankind up here the air is thin and calm and it is here that you'll find the [Music] zepher this is a strange Beast and the fact that it flies this high is the least strange thing about it see it only travels at 40 m hour it only weighs 75 Kg it's launched by hand it's completely solar powerered and in theory it may be able to stay up here for months [Music] I was last at zephyr's base in farra in the UK in 2018 when it had just stayed aoft for very nearly 26 days since then it's done 64 so this is how it works during the day the Sun hits the solar panels which charge the batteries and power the propellers and the plane climbs to 75,000 ft when the Sun goes down the batteries completely take over the propellers do slow down and the plane does lose altitude the trick though is to make sure you're still above 60,000 ft by the time the sun comes up the next morning and the process can start again so will the entire Wing be covered with solar cells every single Square centimeter as much as you can is solar actually uh the solar array that we use now typically is is so efficient that we don't tend to need to Do complete coverage really yeah we can actually recharge the batteries most normal Days by lunchtime wow in theory is it possible to stay up forever in this well I think eventually we'll get as close as we can to that uh at the moment our limitation is the number of Cycles the batteries can cope with uh so a cycle is a day so a full charge and then a full discharge that's one cycle and uh we we're targeting uh 6 months in the stratosphere at a time um and that's in line with the battery performance that we see coming through everything about zepha has been fine-tuned every gram counts every unit of battery density the precise curve of those wings so look I get it I get that this plane can stay up in the air almost indefinitely you only have to look at it to understand that it's something pretty special the main question I have is why why would you want this kind of craft who would want this kind of craft in the 20 years since the idea was first conceived it's almost like this has been a solution looking for a problem would it carry cameras could it be military reconnaissance since Airbus spun off the new startup company Alto in 202 3 it's now being pitched for Earth observation and as a flying base station for mobile phones from the stratosphere at 60 or 70,000 ft we can talk directly to a standard mobile phone so the aircraft will function exactly like the cell tower that you have today but it's high up and because it's so so much higher up than the regular uh cell tower it can cover the equivalent of about 200 base stations on the ground so of course that replaces not just the you know the the equipment on the tower but it replaces the whole Tower that's the steel that's the back hole the fiber the microwave very importantly the power the electricity or the diesel that runs the tower and in many cases in remote and rural areas that's the most expensive part of of running a terrestrial Tower an Uplink antenna would connect the mobile network to zepha and then zepha could serve an area of 72,000 square km in theory for months at a time this is a real proposition or in the event of say a natural disaster a plane could be flown to an area that suddenly become cut off from the grid mobile operators have something called sell on Wheels cow which is usually a truck that has some equipment we have a a cell on wings a flying cow which is flying cell on wings these cows uh planes will fly or autonomously there are no joysticks involved the pilots send the planes coordinates and flight plans but they're mainly interested in how much energy it's using and making adjustments to keep its batteries fully charged so this is the ground and this is 80,000 ft and all this colorful stuff that's wind you don't want to be in that but if you can keep the Zephyr above it from about 60,000 ft and up it's pretty plain sailing the problem is you've got to get to 60,000 ft in the first place something that can take 10 hours from that weird hand launch takeoff trying to get it up into the air is probably the trickiest point there's a lot more weather down on the surface than there is up in the stratosphere so just trying to get the right conditions to get through that weather that's probably the hardest part we spent a lot of time and effort studying meteorology in the tropopause so that we can understand how to Transit through it as safely as possible with this aircraft and we we've now done a global study of where all the weather is uh all the different weather conditions around the world and we found some of the best locations in the world to start launching and Landing these from regularly so where the air is nice and clear all the way up all the way through yeah and once we're in the stratosphere we're away in fact zeph's parent company has just announced Kenya as the location of its first planned permanent launch site but we have seen these kind of Ventures before for example Google's Loon project was also based in Kenya and its balloon-based mobile cell tower project failed to stay afloat and what about satellites these days very small cube SATs can be put into orbit at much lower cost than their bigger siblings and they stay up automatically no power involved although unlike Zephyr you can't bring them down and swap out their payloads with if you want to talk to a handset it's very difficult and if you manage with low earth orbit satellites you can talk to a handset but it would be very limited you know it's SMS maybe a few kilobits per second you cannot do full 5G you're not mimicking what a terrestrial station does and if you have satellites that are really big enough that can do something like this the economics are so expensive and then you're spreading them across the whole planet you're not getting the efficiencies you cannot scale so that's on the connectivity side on the earth observation side satellites are great because they can view anywhere on the planet but not at the not persistently because they take an image come back after a period of time with high altitude platform stations you can do that persistently so you can see the change over time and there is competition in the stratusphere itself similar aircraft to being developed by several companies including this one by BAE Systems whatever the final use for these so-called high altitude platform stations haps the does seem to be both the appetite and now the technology to fly high and stay high

Channel: BBC News

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Id: l7WqP_MYLkM

Length: 8min 33sec (513 seconds)

Published: Sun Jun 02 2024