Cause temperature does affect motor performance, the heat at the back of the hover is mainly the heat gained from compressing the air
The DC Motor Curve
DC motor performance curves can be generated under various conditions. For example, the motor curve illustrated in Figure 1 was created using a rapid test on a motor dynamometer. The test was done by quickly loading the motor from no-load to locked rotor (stall) using a fixed terminal voltage from a power supply with low output impedance. A test like this is done to get a “baseline” measure of motor performance while the motor is at room temperature. Motor shaft speed and current are plotted as a function of motor torque. From this test and a few resistance readings, the torque constant, voltage constant, and terminal resistance values can be determined. This information is very useful to ballpark basic motor performance and can be sufficient for an application that requires intermittent operation with a long rest period between each duty cycle.
A typical motor performance curve created using a rapid test on a motor dynamometer. Such tests give a baseline measure of motor performance at room temperature.
In applications such as repeated point-to-point moves, applications requiring frequent starting and stopping of a high inertia load, or applications that require the motor to be moving for long periods of time (such as a fan application) the motor data illustrating performance at room temperature is not adequate and can result in misapplication of the motor or exceed the motor’s maximum temperature rating.
As the motor temperature increases, the resistance will increase and the torque constant and voltage constant will decrease. This results in an increase in no-load speed and a decrease in locked-rotor torque. Figure 2 illustrates an example of both “cold” and “hot” running conditions of the same DC motor. The “hot” motor curve demonstrates how much the performance can change when operating the motor at an elevated temperature.
The graph illustrates changes in motor performance from room temperature to an elevated temperature, showing how much performance can change with an increase in temperature.