How do we manage this? What can be done to prevent this unhappy situation? Several things really do help. One is common sense and the other is some great, and inexpensive, equipment. First the common sense part.

It is just plain common sense to know your battery’s specifications. If your receiver pack is a 4.8v, 700 mAh battery pack, remember that. Most glow-powered sport aircraft flying with just four standard sport servos use about 110 mAh per 15-minute flight (this is on the high side for safety reasons). This equates to 6.4 flights. But you never know if your battery really has 700 mAh of energy (Ni-Cd’s lose capacity over time) and an unbalanced propeller, high throttle settings or violent aerobatics will cause greater energy consumption.

Larger aircraft and scale machines with electric retractable landing gear can use up to 200 mAh per flight. My Prophecy 2-meter Pattern airplane uses 225 mA per 18 minute flight. Using these figures as guides, do the math for your systems. Know what you have and how far it can go. Btw – hangar flying at home to see how long your receiver battery will last does not work. When not fighting the air stream loads and engine vibrations, your servos are not really working hard and therefore are using almost no energy.