Originally Posted by
Self Loading Freight
Google is buying Titan Aerospace, a company which plans to make solar-powered drones that can loiter for up to five years (they say, six months is probably more like it) at a target altitude of 60,000'. Google says that it's interested in this for, among other things, bringing broadband to developing countries.
A quick look at the specs for these beasts says that they will be able to do around 65 mph. Which doesn't sound much... but apart from the small business of getting up and down safely, is that enough for station keeping for months at a time at that altitude over, say, Africa?
As with all these things it is not a case of average winds, it is what happens at the extremes. The stratosphere is a relatively peaceful place in average winds terms but there would only need to be a week of 100Kt winds and the UAS is a few hundred miles away possibly unable to get back.
However, the more difficult weather to deal with could be vertical windshear in convective storms. The tropopause is not a neat flat layer at 36,000ft it is literally the local altitude at which convection stops. Near the poles it can be as low as 15,000ft and at the equator up to 70,000ft waves form and break in the tropopause its like a giant lava lamp in some regards. In the tropics and especially the Inter-Tropical Convergence Zone, the lines of storms around the equator, storms may reach up to 70,000 ft and the vertical updrafts may be at more than 100kts vertical speed. This would not be a safe environment for a widebody let alone a lightweight UAS.
So it might work - but engineers may have a different view of the reliability than scientists or software engineers.