Many people who haven’t used a Vertiq motor/ESC module before have questions regarding our published thrust data. Admittedly, our data is formatted a bit differently than that of most other motor manufacturers. There are two aspects of our data that can be explained by our modules’ unique configurability and controllability.

“Why is there not a throttle column?”

Before answering this, it’s important to note that all Vertiq modules support three different “Throttle Modes”: PWM Mode, Voltage Mode, and Velocity Mode, which can be configured in our GUI, IQ Control Center. Here’s a breakdown of each mode, and more detailed information on each configuration can be found in our documentation.

PWM Mode

In PWM mode, a 75% throttle command is interpreted as “Command 75% of supplied voltage.” This is the most common way throttle commands are interpreted in the industry, and typically what other motor manufacturers mean by their “Throttle” columns. We discourage the use of PWM mode on Vertiq modules for two reasons.

First, during flight, the supply voltage from the battery will naturally vary. For example, a 12S battery is 50.4V to start, has an average of 44.4V during operation, and is low at 38.4V. So the same 75% throttle could change from the motor commanding 37.8V to 28.8V from the start to end of a mission, which means you'll need to command a higher throttle as you fly to hit the same levels of thrust. This method of throttling is not consistent.

Second, your throttle may not naturally map well to the module-propeller pairing and could cause your propulsion system to overheat. For example, if you run a large propeller that hits the motor module’s continuous torque limit at 36V Commanded Voltage and battery voltage is 48V, throttle commands over 75% in PWM mode could generate too much heat. Vertiq ESC’s have a temperature sensor, and we’ve developed a model to estimate the temperature of the coils themselves. Because of this, our modules are able to derate before hitting temperatures that would damage the motor/ESC.

Note: PWM Throttle Mode is separate from PWM communication. Although we advise against it, PWM Throttle Mode can be used with any communication protocol that your Vertiq module supports (hobby, CAN, UART, etc.).

Voltage Mode

In Voltage Mode, a 75% throttle command is interpreted as “Command 75% of the user configurable max voltage”. In other words, throttle can be mapped to specific voltages. In the above example with a large propeller, you could set max voltage to 36V so that you’re never exceeding the continuous torque limit of your motor. Also, since 36V is below the battery’s low point (38.4V), the motors will perform the same throughout the entire flight, regardless of battery level. A 75% throttle command in this example will always command 27V (36V * 0.75), regardless of battery voltage. A 100% throttle command in this example will always command 36V.

Velocity Mode

In Velocity Mode, a 75% throttle command is interpreted as “Command 75% of the user configurable max velocity.” In other words, throttle can be mapped to specific velocities. Velocity Mode is conceptually very similar to Voltage Mode, but uses actual motor rad/s instead of voltage. In this mode, the module operates as a closed loop controller, applying the voltage necessary to maintain the commanded velocity. If max velocity is set to 500 rad/s and the module receives a 75% throttle command, it will command the appropriate voltage to maintain a velocity of 375 rad/s (500 rad/s * 0.75). We recommend operating your Vertiq module in this mode for the best performance and response times.

Conclusion

With this context, the reason we do not show throttle percentages on our thrust data is because "throttle" can mean different things for different users; “75% throttle” can mean 37.8V at full battery or 28.8V at empty battery in PWM mode, it can mean 27V if you set a max voltage of 36V in Voltage Mode, or it can mean a slightly different voltage in Velocity mode.

Most other manufacturers use PWM on a full battery, and they display the data in 10% throttle increments. We display our data in increments of 1V or 2V, eliminating the variable of a depleting battery supply voltage that frequently makes others’ data confusing.

If you do need to make a comparison to another manufacturer’s data, divide our commanded voltage by supply voltage to find the equivalent to "fraction of battery."

“Why does the data from this test suddenly end?”

Vertiq runs tests to determine the continuous torque limit of all of our modules. We define the continuous torque limit as the level of torque in Nm that the module can operate at in airflow for 10 minutes continuously, reaching a steady state temperature that does not damage the motor or ESC. Torque levels above this limit are achievable, but cannot be sustained without the module getting too hot and derating. There are many variables that affect cooling (mounting surface, add-ons, ambient conditions, airflow from propeller, etc.) and would in turn affect this continuous torque limit. You can read more details about our specific testing setup here. Each Vertiq module’s continuous torque limit is on its datasheet, which can be found on the module webpage.

To give a realistic idea of what to expect from a given propeller and motor module combination, we do not publish the steps of a test that exceed the module’s continuous torque limit. For example, in this test you can see the data gets cut off at the 42V Commanded Voltage step even though our supply voltage is 48V. The torque at this last published step is 1.00Nm. The 60-08 150Kv G2 module has a continuous torque limit of 1.05Nm. When this test was being run, the motor actually continued stepping up in Commanded Voltage all the way to 48V, but was at torque levels over 1.05Nm that would not be sustainable for a significant amount of time. At 48V Commanded Voltage, it was hitting 4,930g of thrust and 1.19Nm of torque. We do not publish those data points to avoid advertising thrust levels that would lead to overheating/derating.

How quickly the module overheats/derates while commanding above max continuous torque is highly dependent on the operating conditions. For example, if the 60-08 150Kv G2 Module with a 20x6” propeller was operating at 18V for 5 minutes (say its vehicle could hover at that voltage), its temperature would be relatively cool. So, if the module was then commanded a voltage above 42V, it would likely be able to run above its max continuous torque level for a long time (30s or more) until it heats up enough to derate. In contrast, if that same module was pushing at 42V for 5 minutes before commanding a higher voltage, the motor could derate extremely quickly (<1s) because it was already at its temperature limit.

In conclusion, our modules can hit torques and thrusts that are significantly higher than our published data, but they cannot always hit those torques and thrusts. As such, operation points above maximum continuous torque should not be relied upon while speccing out a propulsion system for an industrial-grade aircraft.

Most other motor and ESC manufacturers publish the entire test run regardless of whether or not the torques are safe for continuous operation. Sometimes they will indicate which data points are above max continuous operation, but again, whether you can actually hit those specs without damaging your motor is largely dependent on how hard you were pushing the motors before “bursting” up to the higher speed/torque.

Vertiq takes pride in publishing honest and realistic data. If the goal is to produce a high performance and reliable aircraft, we encourage our customers to build in factors of safety into their vehicle. For the propulsion system, this means only using a motor-ESC-propeller combination that can continuously achieve the required max thrust.

Understanding Vertiq Thrust Data