now, if they add some kind of smoke [non-damaging to birds of course] to visualize airflow or some modernized version using some safe laser of something like th

now, if they add some kind of smoke [non-damaging to birds of course] to visualize airflow or some modernized version using some safe laser of something like this http://en.wikipedia.org/wiki/Schlieren_photography http://en.wikipedia.org/wiki/Schlieren_photography