You don't need to check RPM after you start. If you want to adjust for speed run 2 minute flights and adjust for lap time after landing by changing the RPM in the timer. Also, you don't need 6 minutes for a pattern. Most of us in these parts run 5:15 to 5:25. Usually we set the "delay" in the timer for 30 seconds, this will end up with approx. 6 minute flight, a little over counting landing. If you find you have a lot of battery reserve left, you are in luck. Use a smaller battery.
Hi Mike, thanks for your reply.
The six minute number was purely hypothetical. Brand new airplane and power system as well as a 3 bladed prop which I've never used before. Actually the first few flights will be 2 minutes each for trimming purposes. For my first full pattern attempt, I will use 6 minutes just for a margin of safety. As you suggested, I'll dial it back once I get a baseline on pattern duration.
It's funny you mention the 30 second delay. I've used that, and I always feel like I'm standing out there forever, waiting for the motor to start. For competition, I reduced it to 20 seconds and it seems more comfortable for me. If I'm flying alone with my stooge, I usually leave it at 30 seconds.