Tyto Robotics provides drone thrust stands, such as the Flight Stand 500, for testing the large brushless motors and propellers of heavy-lift cargo drones.
The company’s thrust stands allow heavy-lift drone and eVTOL manufactures to optimize the efficiency of their aircraft, which can transport thousands of pounds of weight, including humans, cargo, and other payloads.
The weight these drones can lift primarily depends on the thrust generated by their propellers.
In simple terms, the weight a drone can carry is the difference between its total thrust and the thrust needed for flight. This capacity varies depending on the specific flight parameters.
Calculating Drone Thrust-to-Weight Ratio
When a drone hovers in place (in wind-free conditions), the thrust it produces equals its weight:
Weight = mass x gravity (9.81)
For example, if the mass of a drone is 35 kg:
Weight = 35 x 9.81 = 343 N
The propellers must produce 343 N or 35 kgf of thrust to maintain a hover. For a quadcopter with four propellers, this translates to about 86 N or ~9 kg of thrust per propeller.
However, it’s not that straightforward. Drones often need to take off and maneuver, which requires additional thrust and acceleration.
Thrust Required for Basic Operations
A general guideline for drones is that the propellers should generate twice the thrust needed to hover. This ensures sufficient control for most applications. For drones which conduct tasks like surveillance, videography, or general flying, this rule is a practical starting point.
For the 35 kg drone example, each propeller would need to produce approximately 18 kgf of thrust to provide stable control.
IF1200 Heavy-Lift Drone by Inspired Flight
How to Calculate a Drone’s Carrying Capacity
To calculate a drone’s carrying capacity, determine the additional mass it must lift and verify that the propellers can generate sufficient thrust.
For instance, if the 35 kg drone is designed to carry a 5 kg payload, this will result in a total weight of 40 kg. Using the same formula:
Weight = 40 x 9.81 = 392 N or 40 kgf
The quadcopter would need 40 kgf of thrust to hover and 80 kgf of thrust for stable control. With four propellers, this requires 20 kgf of thrust per propeller.
There are several ways to confirm whether the propellers can produce 20 kgf of thrust each. These methods are covered in Tyto Robotics’ article on calculating and measuring propeller thrust.
Conclusion
In summary, a drone’s carrying capacity is influenced by various factors, with the most critical being the thrust produced by its propellers.
While there are several approaches to estimate a drone’s thrust requirements, proper testing is the only definitive way to confirm its capacity.
