The first thing you should choose when building a custom micro quad, are the motors.
You motor choice will determine how much payload capacity you have, what batteries you need, and what frame and propellers you can use.
There are two types of motors that can be used on a micro quad:
coreless (brushed) and brushless.
Brushless motors need additional speed controllers, are expensive and usually have so low Kv ratings that you need at least a 2S battery to get them up to reasonable speed. Mounting can be complicated.
Until micro brushless technology becomes significantly cheaper, better and easier,
the Micro Motor Wisdom will focus on coreless!
Coreless motors have brushes, so they wear out over time. Factory rating is usually 3-6 hours at full throttle. Moderate use can lead to much longer life times.
Coreless motor can be made with very high Kv-ratings (rpm/Volt), dont need complicated ESCs, and as inrunners, are easy to mount.
Their main advantage for multirotor use is the low inertia, which results in excellent control authority for the FC, which results in incredible stability and/or agility.
Micro Motor Warehouse uses the following motor model code CL-AABB-CC-xx, where:
- CL = coreless
- AA = motor diameter in mm
- BB = motor length in mm
- CC = motor speed in 1000Kv
- xx = special features (pinions, plugs)
Here are guidelines for reasonable all-up-weight (AUW) and payload capacity of a quadcopter built with coreless motors:
By going up a motor size, you add weight for motors and battery. But you also gain additional payload capacity.
By adding a gearbox to the 0820 motors to run a larger propeller, you can gain payload capacity and efficiency (longer flight time), but loose top speed. The Blade 180QX is a good example for a good geared quad.
If a motor model is available in different speed (Kv) ratings, you should choose a higher speed for a light acro build on the lower end of the above weight rating, and a slower speed motor to maximise efficiency and payload capacity when you get near the top of each weight recommendation.