Drone propellers are pretty hard when you touch them. They have a sharp leading edge which cuts through the air so it makes sense that drone blades could be pretty dangerous. Drone motors have a speed of anywhere between 10,000 to 40,000 revolutions per minute. The top speed of the propeller depends on the diameter but it is about 700 mph – all of that makes for a pretty dangerous it of kit. But how do dangerous are they, exactly? In this article, we are going to look at all of the reasons why drones and drone blades could pose a danger to the pilot and the people around it.
Are drone blades dangerous? Yes, drone blades can be very dangerous. They spin at a very high number of revolutions per minute and are made of incredibly rigid materials such as plastic and carbon fibre. The sharp leading edge of the drone blade will easily cut into soft tissue and cause a laceration but they cannot cut a finger clean off.
Bigger drones pose a greater safety risk because their propellers have to be larger and be more rigid since they need to lift a heavier object. Lighter drones like the Mavic mini do not require as much thrust as heavier drones and therefore the injuries sustained by coming into contact with the blades are much less than if you are operating a phantom DJI drone or even something like the Parrot Anafi.
When you have a look at the forums for the Mavic series of drones there are a few opinions that back up the fact that drone blades cause mainly superficial damage. Here is what people have to say about coming into contact with drone propellers:
They aren’t really that bad, from personal experience with my Mavic pro the worst you can expect is a few decent cuts but no stitches at least in my experience.
The Mavic Pro Platinum will draw blood but will be relatively minor cuts. That was across the back of the hand where the finger bones present a lot of resistance. The blades being hinged, keeps the blades from being ridgedly held in place to become plastic knives. That not only protects people from considerably greater level of injury but it also potentially makes the blades less susceptible to damage themselves as well as gives some level of protection to the prop motors as well.
The two quotes above are representative of the sorts of anecdotal evidence that exists on forums about drone propellers coming into contact with hands and fingers.
One thing you need to remember as well is that the drone is probably flying when it comes into contact with your body. That means the drone will quickly fall out of the air before it causes any continued damage on the same area of skin. In the MythBusters episode they hold the drone at high rotational resolution on the same part of the skin and have a go at the area about three or four times before any significant damage occurs
When I had my drone incident I was trying to catch my Mavic air out of the sky and my fingertips came into contact with the blades the drone did not fall out of the sky but I quickly grabbed the drone before it did. So, if you happen to come into contact with the drone you are properly going to do more damage to it than it does to you.
Obviously, drones are dangerous enough that you should always keep your fingers, hands, arms, toes, feet, and other body parts out of the path of the moving blades. There are a number of factors that make the drone blade more or less dangerous the biggest variable is what the drone blades are made from.
What are drone blades made of?
When you buy a drone they are most likely going to be made of plastic or a plastic composite. Drone propeller blades have a massive influence on how smooth the drone flies as well as how much power it can partake. There are loaded people who consider upgrading them to different materials such as carbon fibre.
Plastic propellers are the go to standard because they are soft, semi flexible, and are cheap so that they can be easily replaced. When you are flying a drone that propellers are one of the first things to get damaged and so many drone pilots have multiple sets of propellers in their carry bag. The relative flexibleness of the plastic blades means that they are less likely to crack if they are subjected to a drone crash.
Carbon fibre propellers
carbon fibre propellers are a more expensive and rigid option for drone pilots. These types of propellers are phoned on the higher end drones. Carbon fibre although rigid does not add any extra weight to the drone making them perfect for the construction of blades. The reason people may want to change to carbon fibre blades is that they are less likely to vibrate as they rotate which means a cut through the air more efficiently and generate more consistent left. That means the motors have to work less and results in a more stable flight and less noise.
One of the biggest issues was carbon fibre blades is that they have no flexibility and so even the smallest of crashes could result in snapped blades. Considering that they are more likely to be damaged and they are more expensive the economics of replacing carbon fibre blades means they are less popular with drone pilots.
The construction of the blade
Drone propellers come in a ride variety of construction types. This is generally dictated at the point of manufacture. For example, the DJI Mavic air has completely rigid single piece blades. Whereas the DJI Mavic pro has blades that pivot around the centre column. In their instance of a pivoting blade that centrifugal force holds the blade outwards during flight.
The hinged blades are more likely to give when they come into contact with something. That means that the blades are less likely to cause significant damage as they will yield when coming into contact with something – even if that is your finger.
Can drone blades cut you?
Drone blades can very easily cut you. I have first-hand experience of being cut with my drone:
The drone laid caused a significant amount of bleeding but the wound wasn’t deep and it was only superficial to the end of the finger. The main issue from coming into contact with the blades was the bruising that was caused from the propeller revolving at highly revolutions per minute and hitting my finger a few times. No scar was left but it left me with enough evidence to say confidently that yes drone blades can cut you and it is something that you need to avoid.
One of the questions that regularly get asked is can a drone cut off your finger? Let’s take a quick look at that question.
Can a drone cut your finger off?
If you want a full answer to this question check out my other article – can a drone cut your finger off? Videos from experiments – click here. In this article I have the studies from universities as well as a video of the MythBusters experiments on drone impacts.
The short answer to this is no, a drone cannot cut your finger off. There is plenty of evidence that a drone propeller can cause significant injury to the soft parts of your hands, it just doesn’t have enough power to get through the bone. There have been a number of experiments with commercial and professional drones but none have ever been shown to be able to take a finger clean off.
In 2016, researchers from Aalborg University reported on an experiment that was designed to test the damage caused by a range of drone propellers. They use pork as a substitute for human muscle and skin and fired rapidly rotating drone blades towards the pork. They catapulted the drone towards the meat up to 15 m/s and filmed the impact with high speed cameras which recorded at over 3000 frames per second. Here is the super slow motion video of plastic blades hitting pork:
The scientists found out that the plastic blades shattered pretty much on impact whilst carbon fibre blades do a lot more damage.
So in summary, there’s not any evidence that a drone can take your finger clean off. It would have to get through the bone as well as the soft tissue and half to attack the same area over and over again. I am not saying that in a freak accident or a technical malfunction that this couldn’t happen but it is unlikely during normal operation.
Here, are some of the best ways to avoid getting injured by your drone blades.
How to avoid propeller injuries
one of the best ways to avoid propeller injuries is to stop coming into contact with the blades altogether. This is done through either engineering controls (such as propeller guards) or getting familiar with use procedures so that it is second nature for you to stay away from fast spinning blades.
Let’s take a look at some of the best ways to avoid getting hit by the propellers, below.
Pretty much all of the best DJI drones come with propeller guards. If you want to know about the best drone with propeller guards check out my other article which includes a buyers guide and everything you need to know about buying a drone with propeller guards – click here.
Propeller guards protect the propellers from causing injury or harm to things around it. They act as a physical barrier which means that you just literally cannot get anything close to the drone blades. They are typically made from plastic since it is lightweight and does not affect the drone flight very much. There are a few ways that they can be constructed. The most common way is that they have a bumper bar type construction where the ages of the propeller blade are protected but not the tops and bottom. But there are increasingly more types of propeller guards that completely in case the blades.
The propeller guards do not affect flight very much as they have been designed with the physics and aerodynamics of the propeller in mind. Propellers work by sucking air in from the top and pushing it out underneath the drone. Anything that inhibits this action would severely affect the flight and so a mesh like construction is common if there is protection on the top and bottom of the blade.
Never catch your drone
When I was first getting a demonstration of flying my drone the pilot snatched it out of the air. By quickly grabbing the body from underneath and turning the drone on its side the drone will automatically switch off and assume that it has crashed. This can be an easy way to turn off your drone but it is also a very easy way to catch your fingers in the propellers.
This is exactly what happened to me when I was coming into lands during a drone flight. The only thing that would have made my drone flight safer would have been to land the drone on a clear open bit of flat ground of which there was plenty. I do regularly catch my drone when coming into land and is one of the worst habits that I think I have got.
One of the best accessories you combine for a drone is a landing pad. It is incredibly inexpensive and can be picked up for as little as US$11. A landing pad is a circular piece of waterproof, robust material that springs into shape using metallic or plastic guides around the outer edge. Owning a landing pad not only means that you don’t have to catch your drone due to no suitable place but it protects your motors and camera gimbal from dust and dirt, allows you to take off on snow, sand and grass, and it protects your drone during the riskiest part of the flight – takeoff and landing.
So, never catch your drone – land it and buy a landing pad. If you want to know more information about landing pads check out my other article – do I need a landing pad for my drone? – Click here. In the article I go through everything there is to know about landing pads and have some recommendations on the pads that you should buy.
Safety indicators on propellers
When drone propellers are spinning it is very hard to see them. Commonly drone propellers have a white or brightly coloured band on the tip of the drone propeller. This is because as it spins it creates a circular image which indicates to the pilot that the blades are spinning.
If you are using aftermarket blades such as those for reducing the sound created by the blades cutting through the air – you may not have this very simple safety feature. You can add this safety indicator yourself with a little bit of white texter or you can use vinyl decals for a more permanent solution.
This is a very simple way of protecting yourself and the drone and it will not break the bank but it could be the difference between cutting your fingers and not.
Install a drone safety system
There are a number of companies looking at making drones safer. One example is the Safety rotor system developed by a team from the University of Queensland. This safety mechanism uses a lightweight plastic hoop around the drone propeller. It is light enough that it does not affect flight while also providing protection if anything comes in contact with the plastic hoop stopping the motor almost immediately.
This system uses a series of lightweight plastic hoops around each one of the drones blades. This is explained in the following video:
Although drone safety systems are not as common as you would expect there are still some that you can buy online. It is relatively easy to think that you don’t need a safety feature but it could be the difference between a near miss and a serious injury.
Are drone blades dangerous? Yes they can be if you are not careful. If you follow all of the steps in this article I am sure that you will have a safe flight without incident. If you do find that you have come into contact with a drone blade it is unlikely that they it will cause any significant damage beyond soft tissue damaged.
The experimental data and anecdotal evidence in forums says that even though they are dangerous the injuries are easy to recover from and it will probably result in a fun story to tell other drone enthusiasts in the future.
It’s a good idea not to test this theory out on purpose and keep your digits away from spinning drone blades. Happy safe drone flying!