Been reading a lot of posts re battery life and flying time. I thought it would be a good idea for some sort of timer that reminds you (with announcements) at various intervals of how long you've been airborne. I know you can look at the screen for voltages etc, but sometimes a backup system is handy. There seems to be lots of standalone devices out there, but has anyone come across one (app) for smartphone.... I need iOS but both would be helpful for all members. I don't mind paying, if it works the way we need it to.