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Can drones fly without propellers? Debunking the myths

Updated in 2022 by Paul Posea
Drones without propellers

The propeller is a crucial part of a drone yet highly vulnerable. When one prop snags a tree branch, the center of gravity and thrust are displaced. Therefore, the drone plummets downwards and lands or crashes depending on the number of propellers. However, some drones install propeller guards, obstacle detections, and collision evaders to prevent crashing. The most advanced technology yet is the Impeller drone by Marcus Kung.

Can drones fly without propellers?

While not all drones can fly without propellers, some like the Impeller drones innovated by Marcus Kung fly without propellers. This drone uses centrifugal fans or impellers instead of axial fans to create the thrust and lift the forces. Their arrangement resembles car wheels which aid in pulling the air from the back and out sideways, allowing the drone to take off.

What’s the science behind flying drones without propellers?

This Impeller drone functions like a hairdryer. However,  the air is pulled from the back and sideways instead of out the front. The design, which resembles the arrangement of car wheels, draws air from the sides and redirects it downwards for the drone to take off.

The design of Impeller drones makes them safer from object collisions and irreversible damage to critical elements—a significant drawback with propellers. Similarly, the housing ensures the air inlets are protected by a grill to avoid outside contact. This design creates more force from the outlet flying the drone faster and higher with less power.

A significant drawback of the Impeller is noise. As the air is forced out of the duct, it sounds like a hairdryer. It’s also more expensive than the common drones. Although it’s costly, you will save on replacement expenses prone to regular drones with propellers. 

The science behind flying a drone with propellers

The physics behind a flying drone is simply the ability to combine the four forces of flight; thrust, drag, weight, and lift. This is in addition to their structural design, of course. Let’s explain these forces, the technology, and propeller designs;

The forces 

  • Thrust and drag – Thrust is the force that directs a drone towards the same motion, while drag is the opposing force resulting from the air pressure. When the propellers rotate, thrust allows the drone to move forward. Drag force is used when the drone is moving backward.
  • Weight and lift – Lift force allows the drone to go up when the propellers rotate. Weight, on the other hand, is helpful during descending and acts more like gravity forces. When propellers rotate fast, more lift is generated, and the drone gains speed.   

Drone propulsion technology

The propulsion system consists of propellers, electronic speed controllers, and motors that lift the drones off the ground to hover in any direction. Quadcopter propellers operate in pairs; two propellers rotate clockwise while the other pair rotate counterclockwise to create a thrust, maintain a manageable speed and balance.

The electronic speed controllers (ESC) transmit data from the flight comptroller to drone motors in the direction of flying or hovering. The ESC signals to the drone propellers data on speed, decelerating, monitoring, and fault tolerance.

Drone propeller material and design

The material, design, and diameter of propellers directly impact drone performance. Most quality drone propellers are made of rigid fiberglass or carbon fiber for high-performance. Suitable designs ensure maximum thrust and aerodynamic efficiency, which vary between manufacturers.

Propellers are intended to aid thrust and lift forces; thus, they are fitted with 2 to 4 blades essential during thrust. More blades increase lift force but reduce the weight force necessary when landing. The drone will efficiently handle the drag pressure if your propellers have enough quality blades.

The manufacturing process

The manufacturing process uses injection mold to ensure uniformity and quality of each propeller for advanced drone performance during flight. Each propeller is perfectly balanced with its pair but still dynamic to function exclusively—vital for peak flight performance. This process also smoothens vibration controls during drone operations to avoid compromising image and video quality. With minimum vibrations, drones can operate under harsh weather, for instance, chasing tornado coverage.

Can quadcopters fly with 3 propellers?"

No, quadcopters cannot operate with 3 propellers. A quad drone is designed to operate with 4 propellers, each two working as a pair. All the propellers must rotate at the same speed to keep the thrust, lift the forces and maintain a manageable balance during flight. 

So, how many propellers does a drone need to fly?

Two propellers

Drones require a minimum of two propellers to thrust and balance. The science behind flight involves spinning props which exert equal force in the opposite direction. Thus, the motors need to balance the pressure in each direction—as one spins clockwise, the other counterclockwise.

However, drones with two propellers are not common. Why though? Preventing a drone from spinning is one part of stability, but ensuring thrust is created to propel the flight in the right direction is significant. Although two propellers can fly a drone, controlling it will be difficult due to an imbalanced center of gravity.

Three propellers

Some drones are specifically designed to fly with 3 propellers. Each propeller provides thrust for lift, but one motor must counteract the spin. The rear prop handles balance and provides the thrust for steering while the two spin opposite each other.

These drones have several setbacks; for instance, you have little control over flight, thus, a high crashing risk. The rear prop makes this drone expensive, which can be hard to replace when damaged.

Four propellers

Commonly referred to as a quadcopter. These are the most popular drones in the market as the designs are favorable to both recreational and commercial consumers. Besides the mechanical simplicity, their production cost is relatively low. Each propeller is attached to a motor and functions as pairs rotating (two clockwise and two counter-clockwise) at the same speed. This is to maintain the thrust and lift the forces.

Six and above propellers

Hex and octocopters have 6 and 8 propellers, respectively. The key to flying a drone is symmetry and balance. If the center of gravity is central, these heavy drones can fly when a propeller or two malfunctions during flight, as the rest will take over. Motor burnout is the primary concern with these drones, which is avoided by adhering to the concepts of balance and pairing.

Frequently asked questions (FAQs)

Can I fly a drone with a broken propeller?

It depends on the type of drone you have. Hex and Octocopters have many propellers; thus, they can still fly if they lose or break one or more. However, the flight will certainly not be smooth. Breaking one propeller means the drone cannot create the required lift force and maintain thrust or balance—basic flying principles.

Why do drones need propellers?

Drones need propellers to lift off the ground. When propellers spin, they create an airflow which results in a pressure difference between the bottom and top parts, thus providing a lift to the drone. The spin accelerates a mass of air in one direction, which counteracts gravity, lifting the drone.

Why are most drones quadcopters?

Quadcopter drones are most popular with manufacturers due to their mechanical simplicity. The props are literarily attached directly to the motors, making them simple and low budget. Additionally, the high power-density motor and power semiconductors make them easy to control. Stability, however, is the main flaw in this mechanism.

What should I do when a propeller fails during a flight?

Most drones will lose balance and crash if a propeller fails during flight. However, it depends on the number of propellers, the center of gravity, and thrust. There is nothing much you can do, but you might take preventive measures before a flight. For example, avoid flying close to trees or during cold seasons as low temperatures weaken the blades. It’s also best to thoroughly inspect to confirm that all edges are fit for flight.

How long do drone propellers last?

The recommended timeline is to replace blades at least every three months, particularly the foldable design. However, replace immediately you see scratches, cracks, or deformations. Do not fly a drone with missing tips, especially in crowded areas; it causes too much noise and may crash abruptly.

How do I make my drone less noisy?

To make your drone less noisy, try the following. Install noise-reducing propellers, use noise reduction shrouds or more motors in the drone. You can also adjust the propellers and rotors to reduce the noise or invest in quitter blades.

Let's wrap up 

Propellers make drones fly, but their vulnerability and replacement costs limit most flying. However, there are technologies used to protect them, especially during crashes, so don’t hesitate to fly your drone. The best tech yet is the Impeller drones. Drone enthusiasts will enjoy flying the Impeller drone for its safety net and power conservation, but only when readily available in the market.

author-paul-posea-picture
Hi, I'm Paul.
A big drone enthusiast, reviewing, comparing and writing about drones since 2015. I'm all about helping people enjoy and even monetize their hobby.
paul posea
Paul Posea
Hi, I'm a long-time drone reviewer and I hope my articles and comparisons on this site as well as Dronesgator's youtube channel are of as much help as possible.

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