Getting a quadcopter stable in the air isn’t trivial. Stability of a quadcopter relies on the harmonious working of all of it’s parts.
An unbalanced propeller produces excessive vibration. This vibration travels through the entire airframe affecting the handling of the aircraft, produces inaccurate readings by the sensors, and creates premature failure of motor bearings and parts. A balanced propeller is paramount to a stable aircraft. A balanced propeller produces less vibration and draws less current, which results in greater stability and extended flight times. You should balance any propeller before installing it on your aircraft. Balancing a propeller requires the use of a special tool, you guessed it a propeller balancer. The propeller balancer that I use is the Top Flite Propeller balance. It is essentially a shaft held by two magnets. The magnets create a frictionless surface for the shaft to spin freely. Read More…
Before we can calculate flight time, we need to know the average amperage the quadcopter will draw. Once we have the average amperage draw we can then calculate flight.
To calculate flight time, take the battery’s capacity in amp hours, then divide that into the average amp draw of the quadcopter and then multiply it by 60. The total is the flight time in minutes.
For Scout, I chose a 11.1 volt 30C 3000 mAh LiPo battery. I calculated the average amp draw of Scout to be around 20 amps. This will give me a flight time of 9 minutes.
LiPo charger needs to be capable of charging a 3-cell battery. A battery charger capable of balance charging the battery is also recommended. Balance charging reads the voltage of the individual cells of the battery and charges each cell equally to the other cells. This feature will increase charging time but will prolong the life of the battery and provide slighter longer flight times.
An Electronic Speed Controller, or “ESC” controls the speed of the motor. ESCs will have a power limit. The more power an ESC can handle, the larger, heavier and more expensive the ESC will be. When choosing an ESC, it needs to match or exceed the motor’s peak amperage. If the peak amperage of the motor is 13 amps, then an ESC rated at 15 amps will be sufficient. An ESC with a lower rated amperage will overheat and possibly fail.
Some common features of an ESC are a low voltage cutoff. The low voltage cutoff will cut the power to the motors when the voltage drops to a specific level. This is a protection feature for LiPo batteries. If a LiPo battery’s voltage drops below its minimal voltage, it can permanently damage the battery. The low voltage cutoff protects the battery from dropping below its minimal voltage.
Some ESCs can be programmed to have different throttle responses, adjust the low voltage cutoff limit, reverse the motor’s direction and change the switch rate.