This story has attracted some attention. While seemingly negative about the safety of tethered platforms it actually illustrates one of the central reasons why tethered StratoSolar platforms work reliably by demonstrating why tethered platforms in the troposphere do not work reliably. The air force JLENS aerostat was tethered at about 10,000 feet in the troposphere and the tether broke in a gust of wind during a storm. The story said the wind exceeded 100 MPH and given the nature of wind gusts it probably was a lot more than 100 MPH. The force that broke the tether was a combination of the wind acting on the tether and the wind acting on the aerostat, with most of the force coming from the force acting on the aerostat. Winds in the troposphere can exceed 200MPH, and aerostats are only meant to be operational in up to about 60MPH winds. Many military aerostats are lost to unpredictable winds. This was just a very public demonstration.
In comparison, the worst case wind speed in the stratosphere is about 90MPH and the air is a lot less dense with the result that the worst case wind force is more than a factor of ten lower in the stratosphere. Also there are no storms in the stratosphere so wind force is steady there are no gusts and no vertical wind shear. This relatively benign environment means that StratoSolar platforms can easily handle the worst case winds in the stratosphere and can be permanently stationed there. If the JLENS system were deployed on a StratoSolar platform at 20km altitude, as well as being able to stay permanently aloft in all weathers, it would be able to see more than twice as far and thus be considerably more effective as well as far more reliable and available.
This also demonstrates the difficulty of gaining acceptance for novel ideas. The operational benefits to air defence of a StratoSolar based JLENS are so significant, it would be expected that it would at least get some serious attention. The conventional wisdom cannot see the possibility of the novel and has no motivation to do so.
By Edmund Kelly