Move over Thermomix, drones are taking over the kitchen! Well, not quite, but drones can certainly slice and dice in a very impressive manner! I love showing this ‘drone blender’ video to students and adults alike as it all looks like a bit of fun on the surface. But when you watch those seemingly innocuous plastic propellers dissecting a carrot with ease, and realise that a finger is probably a similar firmness, the video takes on a whole new meaning.
If your imagination can’t quite stretch that far, maybe have a look at what propellers can do to a slab of pork – chosen for its similarity to human flesh. That one is not for the fainthearted and I don’t recommend showing to kids!
It’s really important to note here that I don’t show these videos to instil fear, but respect. Drone propellers are travelling incredibly quickly, so they can actually be thought of as flying blades. At She Maps we work mostly with the Parrot Mambo minidrone. They are flexible and you can easily bend them with some light pressure. And they are really small – just 66mm long, and less than 1mm thick. So surely there’s no way they can cause damage?
WRONG! These tiny propellers can spin at up to about 50,000 rpm. If rpm doesn’t really resonate with you, consider this – with simple mathematics, we can calculate that the tip of the propeller is travelling at 170m/s, or 612km/h! (Thanks to Dr Stefan Maier for working this one out!).
By the way teachers, that’s a great little calculation that you can get your students to do in maths / physics classes…
So what if you were to come into contact with a drone propeller travelling at these types of speeds? The Mambos have prop guards on them, and this will certainly reduce the chance of injury. They are also pretty sensitive to impact, so the motors will stop spinning quite quickly. But in the meantime? Yes, they can draw blood and we have photographic evidence submitted to prove this learning point!!
An injury while the propeller is attached to the drone is one thing, but what about if the propellers aren’t correctly attached in the first place? I have seen propellers fly off drones of various sizes, essentially becoming missiles. It’s pretty scary when it’s a large machine, but even a rogue mini drone propeller could do some damage to unprotected eyes that are a little too close.
Teachers – do you think your students could calculate the distance a loose propeller might travel if it spun off the drone?
The good thing is that we can mitigate the risk of propeller injury pretty easily by following a few safety guidelines when working with these flying kitchen blenders. Here are my biggest recommendations:
- Always wear eye protection.
- Establish a safe distance of operation. I like to use line markings with tape on the ground. Note that CASA regulations require 30 m separation between drones and people / property and you must abide by this law when flying outdoors.
- Establish a safe maximum flying height. I like to keep drones below the standing shoulder height of the shortest participant. You can even set the maximum altitude within Free Flight Mini if using the Mambo.
- Always stand up. Not only does this keep us above the designated shoulder height, but also means that we can quickly move out of the way if need be.
- Always keep hair tied back – propellers tangle pretty quickly in hair! No one wants a drone fascinator do they?