In many areas winter offers up stunning vistas for photographers. This is especially true for drone aerial photography!
But flying in cold weather does come with some increased risks to both the drone and pilot.
Over the years we’ve experienced many of these first hand (remember, DroneTrader.com was started by commercial UAV pilots and drone shop owners) and now we’ve compiled a guide of 11 things you should be aware of when flying in sub-zero temperatures.
Whether you are flying an entry level DJI Spark in cold weather or a fully loaded FreeFly Alta in freezing temperatures, these tips should keep your cold weather weather operations safe and enjoyable.
Let us know if there are any other tips you would like to see added to the list!
11 Tips for Flying Drones in Freezing Temperatures
#1-Keeping batteries warm is crucial!
Almost all RPAS (Remotely Piloted Air Systems) on the market today are powered by lithium polymer (LiPo) batteries. Lipo batteries are great as they are energy dense, high voltage and can be charged and discharged quickly (great for high power draw applications)!
The problem is that they are also fairly susceptible to cold.
Why does this matter?
Well, motors in most consumer and commercial UAVs have a Kv rating (not to be confused with kV or kilovolts) which determines how fast the motor spins with a particular voltage applied to it.
When UAV engineers design a drone they use the Kv rating along with battery voltage and prop pitch/length to determine the torque/speed of the drone.
However, when a drone is subject to cold temperatures, the voltage of the battery drops. This in turn leads to a drop in motor RPM which in turn leads to a drop in power that the drone has for lift and maneuverability.
This can quickly lead to you losing control of the drone and causing an “uncontrolled landing” (read: crash).
So, keep those batteries warm!
How? Read on…
#2-Use Battery Warmers Prior to Flying (if recommended by manufacturer)
Most of the common drones available on the market today are rated by the manufacturer from 32F-100F (or 0C to 40C). Although we do not recommend flying outside of manufacturer specifications there are some best practices you should follow if you do decide to brave the cold.
Using a battery warmer is one of those.
A battery warmer is exactly what it sounds like: something to warm your drone battery prior to flying. They typically warm battery packs to around 15C or so, (just shy of room temperature).
DJI, a leading manufacturer of consumer and commercial UAVs, even builds and sells their own battery warmers for some of their drones. You simply plug your battery into the warmer and it uses a small amount of the battery’s charge to warm the pack prior to flight.
There are also aftermarket solutions available such as this Turnigy programmable battery warmer bag.
Some of the higher end DJI drones such as the Inspire 2 come with an automatic battery heating system built in. These systems typically kick in around 5-10C or below and will heat the battery back up to operating temperature.
#3-Be Sure Battery Packs are Fully Charged Prior to Flying
Although typically not recommended by manufacturers, we are guilty of flying half empty packs when we have no fully charged batteries but still want to “quickly get the shot”. And although it typically works fine, this is DEFINITELY NOT the recommended practice when flying in cold temperatures.
If you refer back to point #1, lithium batteries are quite susceptible to cold, and small changes in battery voltage can have significant effects on power output.
Being sure to fully charge battery packs prior to flight is essential in cold weather. Having an extra few tenths of a volt can give you the extra safety buffer you need to safely land in case of a rapid decline in battery voltage.
#4-Limit the Lengths of Your Cold Weather Flights
If you typically fly right to the “low battery warning” signal we recommend you change this if you are flying in freezing temperatures.
For example, if you are flying a DJI Mavic Pro in cold weather you will typically want to cut the advertised flight time by about half (it has an advertised flight time of about 30 minutes, we recommend flying no more than 15).
This is because the voltage drop near the end of the discharge cycle is typically significantly more precipitous than at the beginning of the cycle.
By cutting the last half of the discharge cycle completely out of the equation you will significantly boost the safety margin of your flight.
#5-Allow for the Drone to Cool Off Prior to Flying
We’ve been talking a lot about keeping batteries warm prior to flying but what may not be so intuitive is that you should actually let the airframe cool down close to ambient temperature prior to liftoff (leaving the battery in a warm, dry location until you are ready to fly).
The reason for this is that modern day RPAS are packed full of tiny, very sensitive sensors that keep the drone level, assess the heading of the drone etc. These sensors need some time to adjust to ambient temperature so that they are not still rapidly adjusting to ambient temperature when flying through the air.
Even 5-10 minutes of leaving a drone outside prior to flying can make a substantial difference in flight stability and reliability.
For some UAVs carrying bigger cameras it is also important to cool down the cameras prior to flying as a sudden temperature change from warm to cold can cause lens fogging. Allowing a cool-down or adjustment period will (hopefully) prevent this from happening.
#6-Be Sure Your Mobile Device and Remote Control Are Fully Charged
We’ve talked a lot about keeping the drone warm, but it is also important to keep your mobile device (smartphone, tablets, screens etc) and remote controllers fully charged prior to flight.
Just like drones, mobile devices and controllers typically use lithium batteries and, like drones, they are also affected by the cold.
Nothing says “pucker factor” like flying a drone on a cold day and having your screen go black mid-flight. Inexperienced pilots may panic and this of course leads to increased risk to bystanders and the drone itself.
#7-Keep Your Hands Warm
Honestly, many of our own flights in cold weather were limited by how much our hands could tolerate, not by the drone itself.
It is important to keep your hands warm, weather it be by using warm mittens or gloves or drone-specific handwarmers such as the Trans-Mitt.
Other commercially available “transmitter gloves” include built in pouches to put in insta-hot hand warmer packs. Most have clear plastic windows which allow you see the screen attached to your controller (http://www.espritmodel.com/transmitter-winter-glove-dc.aspx).
If buying gloves be sure to buy ones that allow you to operate your drone’s controller or mobile device screen! Not all gloves will work on tablet or smartphone screens, be sure to buy ones that work on capacitive screens!
#8-Use a Landing Pad
If you are taking off from the ground in the winter be sure to use one of the many landing pads out there. If there is snow or precipitation on the ground this is especially important.
Rotorwash can agitate nearby snow which can get pulled into the motors. If this precipitation melts inside your motors or near any exposed electronics it can wreak havoc on your drone.
Be sure to buy one big enough to prevent this issue (we like to buy ours from Hooman USA, and prefer to oversize our landing pads when purchasing).
It not only prevents moisture from damaging motors but also prevents snow from ending up on the front of your lens (which will lead to blurry or distorted photos).
Some of the better landing pads (such as the Hoodman we mentioned earlier) include a weighted ring around the outside of the pad that keeps it in place even in windy conditions.
#9-DO NOT Fly In Ice Rain or Freezing Mist!
This is one of those things we never even thought about until we experienced it first hand… We were taking photos of an RV park for the owner just after some fog had begun to dissipate. There was snow on the ground but as we had flown in the cold many times before we thought nothing of it.
We ascended to about 200′ when we suddenly heard a fairly loud sound coming from the drone (a low “rumble” or “droning” noise). Our camera feed also began to wobble violently (despite having a gimballed camera) and so we quickly landed.
What we found was that the propellers had COMPLETELY iced up on the leading edge and as a result were completely out of balance. This in turn led to violent shaking of the airframe and we suspect it would not have been much longer before it fell out of the sky.
What was surprising about this incident was how quickly the icing occured (less than 30 seconds after takeoff)!
A lesson we won’t soon forget!
#10-Be Sure to Carefully Dry Everything After Flying
Moving your UAV from a cold environment to a warm one can cause condensation and the melting of snow. Moisture is never a good idea around electronics, especially not around electronics that fly!
Be sure to clean off your drone (using a can of compressed air or a dry cloth) prior to moving it into warmer environments to prevent any moisture from getting onto the electronics. Be sure to store it in a well ventilated, temperature controlled environment after use.
#11-Use Battery Insulation Stickers
Many RPAS batteries on the market have battery warming or insulating stickers available. These are thick, insulated stickers that are typically applied to the sides of batteries in order to keep any heat the battery generates from escaping. DJI makes insulating stickers for many of their batteries, including the Inspire 1, Inspire 2, Phantom series and more.
Above are a few tips to keep in mind when flying drones in cold climates or during the winter. If have some tips or additional suggestions please let us know at firstname.lastname@example.org!