Similar to aviation, drones can come in a pusher or puller configuration.
In aviation, an airplane with a puller motor (also named tractor) will have the motor fixed on the nose of the plane behind propellers or in front of the wings. Jet planes have motors situated at the back of the plane, exercising incredible thrust. They’re classified as pushers.
Now, for a drone, this can be slightly confusing. But stay tuned because this article will explore everything you ever need to know about puller and pusher drones and which is more efficient.
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Only a minimal number of drones have the pusher configuration. In this scenario, the drone will have the motors mounted lower on the frame and upside down, with the propellers facing the ground.
Statistically, a pusher drone can generate more thrust and has better energy management. If so, why don’t we see more of those, and why they are so rare?
It’s because of the overall control and aerodynamics. While a pusher drone DOES generate more thrust, it also induces a lot more air drag, which can be daunting for fine-controlling the drone.
One example of a drone running under such a configuration is the iProtek 25 Pusher version.
Another major disadvantage of a pusher drone, FPV, in general, is that when the drone lands, it can land on the top nose of the propellers with a high risk of damaging them.
Also, it means that hand-landing a drone is totally not possible. But we’ll get more into that later.
Yet another fantastic example of a pusher drone is the DJI Avata. That’s a great example of a pusher drone. Maybe that’s why it has a few issues tumbling over when aggressively turning yaw or facing higher winds.
- It has better thrust due to less air friction when propellers push air.
- More satisfactory energy management.
- Pusher drones hover better and can perform excellently with slow-type flights.
- Overall, the aerodynamics of such drones result in a bit more flight time if the power management is offset correctly.
- The gravity center can be slightly off due to the motors and propellers’ positioning on the drone, increasing the chances for pusher drones to tumble. A case in point would be DJI Avata.
- It requires better adjustments and configurations to make these more stable for flights.
- Pusher drones have more air drag, and more vibration can be induced.
- When landing a pusher drone, propellers and motors are more exposed to cutting grass and getting damaged by uneven surfaces (of course, it all depends on the drone’s structure)
The drones we often see in the sky, and even the classic graphic representation of a drone, are indeed puller drones.
These are the standard type of drone where the motors are placed above the arm with the propellers facing upwards.
While these drones generate a little bit less thrust than a pusher drone, they are more stable, safer to fly and use, and have better control overall.
Because of the drone’s aerodynamics, some puller drones also benefit from the rapid cooling of internal parts due to the propeller’s placement (slightly above the drone). While it’s not always the case, it is something worth mentioning.
- A puller drone (tractor) has better flight stability and less air drag, which can result in better control.
- Puller drones are more suitable for a transit type of flight (e.g., long-range) and for performing drone deliveries, although pusher drones can lift more.
- Worse energy efficiency: it was scientifically proved that tractor/puller type of drones have a less efficient energy consumption ratio than pusher drones
- The thrust resulting from puller drones is noticeably worse than the pusher. A puller drone’s aerodynamics prove that motors must exercise extra thrust to compensate for the air friction a drone’s design induces.
Efficiency vs Stability
Ultimately, it may not be a personal choice if you’re looking for the best drone build, whether we’re talking about standard GPS drones or an FPV drone.
We need to follow the scientific process in order to benefit the most from a drone, and overall, it is better to own a drone type of puller (a.k.a., tractor) where the motors and propellers are facing upward.
That would be an overall choice even if the pusher drones have better thrust performance and power efficiency. These pusher drones prove to function better at slow speeds with improved hovering stability.
Ultimately, we have to look at the bigger picture. How are most drones on the market built? And I am talking about the large majority, approximating over 90% of the drones.
They are all pullers (tractors) with the motors and propellers facing upwards. The air is pulled directly from above and pushed through the drone propellers, where the arms and drone build play a crucial aerodynamic role for better efficiency.
Building your own FPV drone – Puller or Pusher?
Now, it would all depend on what you’re looking to do with the drone.
Pusher drones are better when we’re considering the Cinewhoop side, as they’re especially suited for slow-type flights and longer flights.
At the same time, puller drones have proved to be more efficient in freestyle control and racing. They also can reach extreme speeds, although pushers have better lift-to-weight ratios.
So, if you’re confused by the whole mechanism and structure and are undecided on what to pick, it would be ideal to simply go with a puller (tractor) type of FPV drone.
Pushers also require more PID tuning and Betaflight configurations to make them more stable in flights.
And let’s not forget, pusher drones can also suffer from occasional tumbling, especially if you put a larger battery on top of the drone and the gravity center is off-put by the motors and propellers positioning on the frame.
Fixed-wing: Pusher or Puller?
When we refer to the home-built and custom type of fixed wings (amateur), going with the tractor (puller) type of configuration where the engines and propellers are set in front of the motor/wings or on the front of the plane are highly efficient and provide much better stability.
This is because the propellers are placed in front of the gravity center of the fixed-wing drone.
8-rotor Drones: Pusher and Puller
There are a few rare exceptions where some drones are built with eight rotors instead of four.
Here, we have the type of multi-rotor drone with eight arms, and on each arm, there’s a motor with propellers (usually tractor). They are most efficient at lifting heavy objects and exercising a high lift-to-weight ratio.
Also, I’ve seen one unique design where two motors with two propellers are situated on a drone arm, one facing upwards and one downwards – basically pusher and puller at the same time.
Now, in the logical conclusion, an 8-rotor drone would do better if each of the motors is set to an individual arm, proving to be more efficient in lift-to-weight ratio and energy consumption.
The aerodynamics of both push/puller drones with two motors and propellers on one arm may play a significant role. A lot of air energy is lost when the top motor (tractor) pushes air through the blades on the pusher motor and blades.
The energy efficiency can be reduced, especially if the top and bottom motors are rotating at different RPMs (which they shouldn’t).
In the world of science, tests and experiments have been performed for both pushers and tractor (puller) types of multi-rotor drones to prove their efficiency and provide results that may serve the final product better.
A paper was published at the University of Michigan called Experimental Investigation of Tractor and Pusher Hexacopter Performance by Prashin Sharma and Ella Atkins. Various experiments were performed in different dynamic tests, such as wind tunnels.
Eclectic experiments concluded that pusher drones have a higher lift-to-weight ratio but are also traded against a lower lift-to-drag ratio for this type of hexacopter design.
On the other side, puller drones, also known as tractors, are more efficient in proving better stability and flight dynamics, but at the same time, they consume a greater amount of energy to provide the same thrust performance as a pusher Hexacopter.
In the experiment, at slower speeds of 2.2m/s, the tractor hexacopter required 7% more energy than the pusher version from the experiments performed in the wind tunnel.
A pusher design is more efficient for hovering and slow flight missions, such as local-area surveillance and inspection, whereas a tractor design is more efficient for missions requiring appreciable transit, such as package delivery.By Prashin Sharma and Ella Atkins in Experimental Investigation of Tractor and Pusher Hexacopter Performance
I am aware that this article became very technical, but there’s a logical reason and experimentation to prove the efficiency of both pusher and puller drones.
To conclude this, I will make it very simple in a few lines:
- Puller drones (tractors) are better and more common. They are found everywhere, and most drones have a puller configuration. They are more efficient at flying longer ranges and have better stability, control, and less air drag.
- On the other side, pusher drones have better hovering stability and perform better at flying at low speeds; they also have better energy efficiency and higher lift-to-weight ratio, but they’re also prone to propeller damage depending on the drone structure, and you can’t hand-land a pusher drone.