I bought a little digital count down timer at Radio Shack about 15 years ago and it still works. I ripped off the cheesey little clip and epoxied a clothes pin on the back. It beeps. So you don't need to look down to see how much time you have. And its small and light weight. They use watch batteries that are readily available and last for several years. I fly until it beeps and then land. So give yourself about 20 or 30 seconds.