Prismatic, along with BAE systems are planning US-based flight trials in 2021 for the PHASA-35™ stratospheric HALE UAV programme. The expected trial follows on from successful initial flight trial, functional and performance testing. 

Further details can be found at: 

https://www.baesystems.com/en-us/feature/bae-systems-advances-phasa-35-testing-for-us-flight-trials