Drone Propellers (Beginner’s Guide)

Watching or operating a drone is amazing. But, have you ever wondered how it takes off and balances in the air? Well, it’s not magic, it’s physics!

So, how do drone propellers work?

**A drone’s propellers are essential to keeping a drone in the air. These spinning blades produce airflow, which lifts the drone in the air. When selecting propellers for your drone, choose some that have a pitch that is compatible with the drone for smooth operation. **

Propellers come numbered to show size, pitch, and the number of blades. Smaller propellers have a high pitch for fast maneuvers. Larger ones have a low pitch and are ideal for steady flight required for aerial videos.

The extensive guide below covers everything a beginning drone pilot needs to know about drone propellers. I’ve explained things in a way that will be most helpful for first-time drone pilots or those that want to improve their drone’s performance.

What are drone propellers? (Explained for beginners) #

Drone propellers are one of the most basic parts of a drone. They are the blades that spins rapidly to create airflow. This replaceable part acts as a propulsion system that lifts a drone, making it fly.

But, it’s more complicated than simply going up and down. You want to be able to move around up in the air, right?

Each propeller has a specific role. When you change the speed of individual propellers, you make the drone hover, ascend and descend, or go forward and backward, etc.

Additionally, the airflow produces pressure variations between the upper side and below the blades. So, the lift occurs when high-pressured areas move towards low-pressure areas, creating lift. Got it?

Let’s look at the functioning of drone propellers a little more in-depth, but in an easy-to-understand way. Keep reading.

How Do Drone Propellers Work? #

Drone propellers spin at a specific speed to push the air down. Then, an air shift occurs, causing the drone to be pushed up. So, faster spinning of the propellers creates greater lift.

Understanding how drone propellers work isn’t as complicated as you think. But if you find it hard, here’s a simple explanation.

Do you know how the wings of an airplane work? Yes, no? The same concept applies to drone propellers.

The propeller on your drone is called a wing. More specifically, it’s a combination of multiple wings fixed together. When the little wings spin around, they generate a low pressure pocket directly over them. The air underneath is trying to get to the low pressure area to balance out. As the air underneath the propellers moves up, the drone is pushed up too. This is called lift. 

A flight has four forces: lift, thrust, weight, and drag. Thrust moves the drone in the same motion direction and works against drag. Conversely, weight uses gravity to restrain the effect of lift.

Therefore, when all the forces strike a balance, the drone flies at a balanced level. 

Which way do drone propellers spin? #

Drone propellers also allow speed changes that affect the direction a drone flies. This causes the drone to spin in a different direction as follows:

• Yaw: This is the right or left swiveling of the drone’s head. It’s the basic movement for spinning the drone—most drones yaw by using the left control stick to the left or right. To achieve this, propellers in a diagonal pattern will slow down.
• Pitch: It’s the forward and backward movement of a drone. The drone pilot achieves forward pitch by pushing the throttle stick forward. Conversely, backward pitch involves moving the throttle stick backward. To speed forward, the front propellers will rotate at a higher speed than the hind propellers.
• Roll: Usually, roll and yaw confuse many people. Roll means flying the drone to the left or right. Roll uses the right throttle stick to make sideways movements. And to achieve this movement, the propellers or rotors on one side will slow down depending on the direction you need the drone to go.

How to choose the right drone propeller #

Drone propellers are different. They significantly influence the drone’s power, affecting how smoothly it flies.

Therefore, the following considerations are important when buying new drone propellers.

Pitch #

Pitch is the traveling distance of the propeller per each revolution.

In simpler terms, low pitch generates less turbulence and more force in the air. This makes the motors work effortlessly in carrying heavy payloads. Also, it results in increased flight time since the motors use less current from the battery.

 On the other hand, high pitch produces less force and more turbulence in the air.

It’s very important to ensure that the propeller’s pitch is compatible with your drone. A propeller with an angle outside the requirements of your drone will not function properly.

Diameter #

A propeller with a larger diameter enables more contact with the air. As a result, it causes more stability when the drone is hovering.

However, a smaller diameter takes more effort when maneuvering smoothly in the air. Still, they speed up or slow down easily hence being more responsive than their larger counterparts.

More factors to consider include:

• Air density
• Blade material
• Maximum noise
• Power
• RPM

In summary, the type of propeller blade you choose determines the drone’s flight efficiency. Still, consider what you need the drone to do in order to choose a propeller accordingly.

Size and numbers: how do I know what size propeller I need for my drone?  #

That’s a common question for most beginners when looking for drone propellers.

Smaller blades, usually under eight inches, are popular for racing and acrobatics in the air. Typically, smaller blades pair well with smaller motors with high kV ratings (link).

Those over eight inches are larger blades, and they pair well with motors with low kV ratings. Drones with larger blades carry heavy loads like video equipment and spraying containers.

Propeller blades vary on the usage, platform, and payload requirements. Propellers come numbered to help you understand them better. So, you should pay attention to the tiny numbers on your propeller blades.

What do drone propeller numbers mean? #

Usually, describing propellers is done using three numbers with an X in between each. These numbers refer to size, pitch, and blade count. Let’s look at an example.

A propeller can have a 5×4.8×2. The first number, 5, relates to the size, mostly in inches. 4.8, the second number, indicates pitch and is also in inches. Lastly, 2 is the number of blades, which shows a 2-bladed propeller. So, it’s Size x Pitch x Number of Blades. As simple as that!

How Long Do Drone Propellers Last? #

**It is best to replace your drone propellers after 200-500 flight hours or every three months. **

Drone propellers are inexpensive and among the most ignored replaceable components of the drone. Replacing a drone propeller is easy and you can DIY. It would be best to replace them regularly to save you many issues like drone crashes.

Above all, please avoid flying your drone with broken or faulty propellers. Wear and tear on the propellers vary greatly. Any sign of damage calls for a replacement, and that’s not necessarily after a fixed time or number of flights.

Factors that determine how long props last #

Material #

Drone propeller blades come in various materials like plastic, carbon fiber, and wood.

The most preferred material for drone blades is carbon fiber because of its many advantages. Carbon fiber blades are the strongest, stiffest, and lightest of them all. Also, they offer less inertia and vibration, allowing for faster speed change.

On the other hand, plastic propellers are more flexible hence can bend easily without damage. Also, plastic props won’t chip or crack easily and don’t require frequent replacements.

Lastly, wooden blades are heavier and unresponsive to speed changes. Also, the weather greatly affects the wood, like rain. Constant dampness can cause decay.

Usage #

For starters, a skilled drone pilot knows how to avoid drone accidents. The pilot understands that the propellers’ pitch, weight, size, and design vastly impact how the drone flies. Besides, the set of propellers is the first thing to get damaged in a drone accident.

An amateur, however, is likely to need to replace the propellers or even the whole drone frequently. This is because they don’t know how to control and care for it in the air.

Furthermore, different propellers have varying functions. This depends on the purpose of your drone in the first place. So, ensure you work with compatible propellers for maximum durability.

Care and Maintenance #

Undeniably, how you care for something determines how long it lasts. Drone propellers aren’t an exception.

Your proactiveness in caring for your drone establishes its durability. A drone owner should do everything possible to ensure the propellers are always in peak condition. They shouldn’t bend, warp, crack or chip without your noticing.

So, how should you care for your drone propellers?

• Before each flight, ensure the propellers are firm and spin properly.
• Do environmental checks to ensure you fly in a safe zone without obstacles like trees and power lines.
• Clean your propellers after every flight. Use a toothbrush and toothpaste to remove the dirt and grime. Wipe with a soft cloth and be sure to dry them well after cleaning.
• Remove the props and clean the gears and movable parts as well.
• Check for cracks or warping near the hub before attaching the propellers back to the housing. Do this by bending them lightly for better visibility. In case of any damage, throw them out and get new ones.

As observed above, it doesn’t matter if your drone propellers have 200-500 flight hours completed. It would be best to replace your props immediately if there’s a crack, warp, or any form of damage.

Fortunately, propellers are cheap and easily replaced. Therefore, it’s a good idea to always have an extra pair with you when you take out your drone for flying. Besides, you never know what might happen!

Reasons you might need to change your drone propellers #

Props coming into contact with other surfaces #

Sometimes, it’s hard to avoid obstacles when flying your drone. It’s not unimaginable that you might happen to clip overhanging things like a hanging tree branch.

If this happens, the propellers are spinning at high speed. Therefore, the smallest touch can damage the blade’s edge.

When your drone clips any surface, you should land immediately. But, if you can’t land instantly, allow the drone to hover for some time. If this happens, check for:

• Any changes in the noise it makes
• Hovering stability at a specific level

After landing heavily #

The best practice is ensuring your drone takes off and lands smoothly. However, heavy landing can be inevitable in strong winds or uneven landing spots.

Plus, your drone may lack an auto-landing feature. So, the manual one may lands the drone quickly and heavily, depending on the pilot’s skill level.

Therefore, if you experience heavy landing, check for cracks in the propellers. Consider swapping damaged propellers immediately.

Presence of warping #

The shape of the drone propellers contributes significantly to their performance. It creates a low-pressure area on top of the propeller lifting the drone. In short, a drone relies on the intensity of the air passing over the drone propeller to work.

So, any slight adjustment to the propeller shape prevents lift. It would help to check through all the propellers to ensure the shapes are the same and in good condition. Swap immediately in case of any warping.

But, what causes warping?

Things like heat, UV rays, poor storage, and old age cause warping. Replace your propellers even if you notice twists, bends and bulging on the surface.

It has cracks #

Four forces act on the propellers when they are functioning. These forces can cause cracks and slight fractures invisible to the naked eye.

But, you can use your fingertips (as they are very sensitive) to feel through the surfaces of each propeller. Trust your fingertips to detect even the slightest cracks on the props. Replace any cracked ones immediately.

Usually, small cracks turn into large ones over time. So, don’t ignore the color change and replace them instantly to guarantee safe future flights.

Damaged leading edge #

A drone propeller has a leading and trailing edge. The leading edge faces the direction of the spin. Normally, the leading edge can become damaged if it comes into contact with debris when taking off or landing.

Also, the propeller can attract bees and other insects. As a result, you may notice small chips on the leading edge surface. Again, run your fingertips on edge to feel for any chips or damage. If there are any, change the propeller immediately.

Preferably, invest in a drone landing pad to ensure safe landing without hitting sticks or small stones. The best thing about a landing pad is that you can use your drone even in places without a smooth landing surfaces.

Damaged trailing edge #

The trailing edge faces the opposite direction of the spin. It comes curved, lower, and longer. As with the leading edge, use your fingertips to check the condition of the trailing edge.

The trailing edge doesn’t play a major role in the flight’s stability. However, it can affect the drone’s noise while the motor spins. So, pay attention to the noise and know the status of your props.

When discoloration occurs #

Change your propellers immediately if there’s any discoloration. A good drone flies in all weather conditions. Because the props are usually thick polymers, the UV rays can damage and discolor the surface.

Discolored propellers are a sign that the material is becoming weak. So, change them immediately if you notice even the slightest form of color change.

How to replace drone propellers  #

Follow these simple steps to change the propellers on your drone:

1. Press down the release tab on the propeller guard and remove the propellers by pulling from the drone.
2. Use a screwdriver to unscrew the security screw from the propeller blade.
3. Pull the blade up and out firmly from the drone. Ensure the silver top piece comes off as well.
4. Take note of the small hole in the rotor assembly. It acts as the connection hole for the replacement blade.
5. Take the compatible replacement blade and connect it to the rotor assembly. Before installing, make sure you align both blade holes and the rotor assembly.
6. Use the precision screwdriver to fix the security screw in the installation hole. Screw it in tightly to make it firm on the rotor assembly.
7. Place and press down the silver top piece onto the rotor assembly.
8. Put the propeller guard back into its housing and press down the tab to secure it in place.

Before you take off again, double check to ensure proper propeller rotation direction. Usually, props produce maximum thrust when they turn in one direction. Drones come with two sets of different props. One set has clockwise props that move around toward the right, while the other comes with counter-clockwise props.

Why do drone propellers spin in different directions? #

Propellers spin in different directions to counteract torque.

Usually, props produce maximum thrust when they turn in one direction. Drones come with two sets of different props. One set has clockwise props that move like a clock, while the other comes with counter-clockwise props.

Spinning propellers push down the air. Because the forces come in pairs, the rotor pushes the air down while the air pushes the rotor up. This is the basic concept that supports lift.  

If the propellers were all spinning in the same direction, the drone would tend to twist around against the direction of the spinning propellers, in response to the force of the air being pushed away from the drone. 

Always ensure proper propeller rotation direction for the drone to be able to fly properly.

Are drone propellers the same? #

Generally, drone props aren’t the same. Hence they aren’t interchangeable. The difference is in the motor’s size, shape, and connection. However, the same make and model of a drone can use the same and interchangeable propellers.

Sometimes, buying propellers in bulk is a cost-saving idea, especially for people with multiple drones. However, to buy in bulk means they should be all the same. But are they? Let’s find out.

Different drone models take off differently because of different-sized propellers. Though different, each propeller works in sync with the others. They lift the drone just enough not to make it get out of control. 

Besides, a tiny drone doesn’t work well with the same propeller size as a large drone.

Believe it or not, money also affects the sizing of props. You see, most brands focus more on their profit margin than a customer’s needs. It would help if all propellers came in large quantities of the same size for all drones.

However, the manufacturers don’t appreciate the idea. Instead, they make propellers with distinct pitches and diameters. This way, it’s impossible to replace propellers with a different brand.

Drone propeller types #

Drone propellers come in several types that fall into different categories. These categories include:

Tapered propellers #

Tapered propellers are the regular type of propellers. These propellers feature a noticeable tip and a thinner body.  

Because of their small surface area, they rotate at a high RPM generating enough thrust for the drone.

Generally, tapered propellers use less energy as compared to other types. Still, these propellers are great for people who focus on aerial video and photography.

Bull-nose propellers #

Bull-nose propellers are the new member of the drone industry. Those props consist of thicker and blunter tips than the tapered propellers.

Their larger surface area produces more thrust. However, bull-nose propellers have a heavier weight that consumes more energy. The more energy used equals reduced flight times.

Also, the length of a bull-nose prop is shorter than tapered props. Mostly, these props work best on racing drones. They work best with experts who don’t mind spending more flight time to get greater speed.

Folding propellers #

Folding drone propellers are popular in personal and commercial drones. This is because of the issue of portability. Nowadays, drone pilots need to carry their drones everywhere, even on vacation. Therefore, a portable and compact-sized camera easily folds up, taking less space in the luggage.

Suppose you’re wondering if the folding props affect the drone’s flight performance- they don’t. Besides, they provide an advantage over fixed propellers.

Folding props are better shock-absorbers limiting the torque from hitting the propellers.

The worry of propellers folding during flight is common. However, this hardly ever happens. In worst-case scenarios, the props fold slightly, decreasing the propeller length. If this does happen, it reduces the level of efficiency.

Different blade configuration #

The two-blade or three-blade propellers are the most common propellers for many drones lately. But, there’s even a four-blade and a five-blade prop.

Drone propellers range from two-blades to six-blades. But why is the six-blade propeller not as common?

More propeller blades make you lose efficiency. Normally, more blades equal increased thrust per rotation. This is because of the increased surface area you get for each rotation.

However, this is costly to maintain. Many blades in a propeller use high power, thus demanding more battery energy for a complete rotation.

You should also know that more blades are ideal for increased stability depending on your drone’s motor power. But, you should be ready to replace your drone battery sooner than later. This is because many blades decrease the total flight time of your drone.

How do you balance a drone propeller? #

Do you sometimes feel that your drone is shaky when you’re flying? Well, that’s not your nerves acting up but rather the effects of imbalanced drone propellers. But, worry not, it’s easy to fix.

Balancing the drone’s props is among the specific things you can do to ensure a perfect flight. Besides, imbalanced props cause excessive vibration from the heavier blade. This causes more wear and tear on your motor. It also makes taking your video or photos close to impossible.

Here is how to balance your drone propellers:

1. Detach the props from the drone. You can simply push up and pop off the propeller from the C-clip to take the prop off.
2. Place the propeller shaft horizontally, preferably on a sheet of paper.
3. Put the drone propeller on the shaft and rotate it. Take note that a balanced propeller spins at a perfect horizontal angle.
4. Ensure the blades are spinning horizontally. You can use repair tape on the props to achieve that.
5. Attach the propellers on the drone. First, put the shaft in, then fix the blade to it. Ensure the connection is nice and firm.

Expect the drone to fly and hover more smoothly once you achieve a perfect balance for the propellers. This reduces the vibrations that wear out your motor and bearings and helps you to be able to take perfect videos.

Are 3 blade props better than 2 for drones? #

**In terms of speed and efficiency, 2-blade props are better, especially in lightweight drones using less powerful motors. But, 3-blade props are a suitable choice when prioritizing stability and extra thrust. **

A common argument in the drone community is 3-blade props vs. 2-blade props. Let’s join the debate with the facts below to establish which is better.

2-Blade Propellers #

As the name suggests, 2-blade drone propellers consist of two blades. When it comes to mechanical efficiency, fewer blades make the drone more efficient. Therefore, 2-blade propellers are better than 3-blade props in this case.

But, efficiency doesn’t lift a drone, thrust does! Thrust is necessary for a drone to overcome drag and its weight, eventually causing lift. So a 2-blade prop produces less thrust and doesn’t work as well on weighty drones with powerful motors.

Additionally, 2-blade propellers perform well with a fast motor response where the amount of thrust isn’t crucial. That is why many racing drones feature 2-blade propellers – because they are super light, requiring minimal thrust. As a result, a 2-blade prop generates greater response and speed. 

The durability of 2-blade props is an essential yet most ignored factor. For beginners, it would be best to start with 2-blade propellers. Why? In times of a crash, they can spin out of the way, reducing the risk of damaging the propeller. Unlike the 3- blade prop drone, which is impossible to hit the ground without damaging two blades.

Pros

• More efficient
• Higher speed
• It makes a better folding design
• Light and portable
• More durable

Cons

• Affected by wind since it’s lightweight
• Noisy
• Reduced stability

3-Blade Propellers #

3-blade propellers come with three blades that generate more thrust. As observed above, thrust lifts a drone, and the 3-blade props carry more weight.

That’s why manufacturers install 3-blade props on heavy drones due to the more powerful motors they possess. They are also more stable because of the greater thrust they generate.

Their other benefit is flying smoothly even when imbalanced. Unlike 2-blade props, this perfect must-have balance causes vibrations when spinning (link).

Pros

• Powerful with better thrust
• Highly stable
• Less noisy
• Heavy hence not affected by wind
• Provide better tips for tracking

Cons

• Not fast
• More vulnerable to damage
• Not portable

So, which is better; 2-blade props or 3-blade props?

From the explanation above, it’s hard to determine the most efficient drone propeller. This is because the flying conditions and type of drone will affect your choice. Above all, your selection is determined by what you want to achieve. 

To read more on this discussion of 3-blade vs 2-blade props, check out our article over here » 

How do you calculate drone propeller thrust? #

Calculating thrust is important to ensure you select proper working propellers and motors. Static thrust is the thrust a propeller generates when stationary to the earth.

This calculation is essential because drones can perform at low speeds proportional to the ground. Therefore, static thrust calculations ensure that low-speed performance works on different flight conditions. Above all, you should note that the final results are estimates and not actual values.

Ideally, calculating drone thrust involves knowing the specs of the motor and propeller.

Every drone manufacturer provides a data sheet that you can use to calculate the thrust from each motor. So, the total thrust produced by each motor is multiplied by four.

There’s also another easier but dangerous method. Reverse your propeller and weigh it on a weighing scale while on full throttle. The danger comes in if you don’t do it properly. However, this method gives the exact thrust for your model.

Can Drone Propellers Harm You? #

Yes. Drone propeller blades are sharp enough to cut through the skin when rotating at high speed. The most vulnerable parts are your fingers, neck, and eyes. However, propellers are not harmful when they aren’t spinning.

Drone propellers are like blades attached to a drone’s motor. The propellers rotate at high speed when switched on, making them dangerous.

The size of the drone determines how the severity of the injuries is. Why?

Bigger drones have larger and harder propellers, which can cause deeper and worse cuts at high speed.

However, any size of a fast-moving prop causes severe injuries that may even need stitches. All in all, it would be best to take safety precautions when handling drones.

Why?

They can hurt you when:

They fall down #

First, ensure all drone parts are properly functioning before launching it. Any technical malfunctions can cause a drone to fall and crash, causing accidents. Also, there are high risks of being hit by a falling drone propeller in the drone’s airspace.

How heavy a drone is determines how forceful its fall is. That said, they fall with their propellers first hitting a surface. So, if you’re in its path, the propellers can hit your head and neck, causing bruises and even concussions.

A drone crashes #

If you don’t know how to steer a drone, or something happens and the drone drifts, you’re likely to cause collisions. Aside from crashing into other drones, you can also crash your drone into someone. Because the front propellers hit the surface first, their high speed is likely to cause harm.

To read more about the dangers of drone propellers, check out our article over here. 

FAQ #

Q: How do I know what size propeller I need for my drone?

A: The size of drone propellers is compatible with the drone’s size. Small drones have small blades, while large drones have larger blade diameters.  Also, ensure you check the blade size from the prop numbers. This will help you pair the propellers to the drones accordingly.

Q: Which is the most efficient drone propeller?

A: The most efficient drone propeller has fewer blades. Few blades are lightweight hence offer greater speed compared to many blades. Therefore, the most efficient propeller is the 2-blade propeller. Select a brand that is known for making quality drones and propellers.

Final Take #

Do you care how your drone functions?

According to the drone propeller guide above, the function of drone propellers is clear. A drone propeller makes a drone fulfill its function by taking it up in the sky.

Finding the right propellers is a major step to efficient and safe flights as a racer, or if you want to build your own drone.

Find out what works and feels best for you, and is energy-efficient, not to mention cost-effective. But remember, don’t get too attached to your propellers as they need regular replacements.

Fly away!

Photo by Mihai Moisa on Unsplash