TRL 7 is achieved

See page 5 about the current TRL of several prototypes:

See also the dicussion about the question of the two main technologies (yoyo and flygen) that are investigated on:

Makani’s device TRL 7 leads to a possible marketing by soon. If it doesn’t occur other criterions should be parameterized such as power/space ratio, passive reliability added to computerized reliability, public acceptance and so on.

Technology readiness level

Let’s keep in mind that these TRL ratings are based on one person’s judgement who might not have access to more information than we do.