Plan on Flying Your Drone This Winter?

Ok everyone….while I’m sure most of my friends in the North have been dealing with this for about a month now, I’m in Texas and it just now started getting cold.  So I figured it was time to remind everyone about how to fly in cooler weather without ruining their equipment.  For those of you unfortunate enough to not live in Texas, I’m sorry for getting this out so late, hopefully you figured it out 🙂

What Happens When it Gets Cold?

Aside from my wife stealing all my thick socks and trying to ‘warm up’ by touching me with her iceberg hands, there are some very important changes that occur when the weather turns frosty.  The short answer is, “things slow down and get closer together.”  This applies to air molecules (and people, in my experience.)  Colder air is denser, and allows props and rotors to provide more thrust/lift than when it is warmer.  That’s great right??  Yes, but it’s not all sunshine and roses, as the cold weather can have a negative impact on the battery and other flight systems.  Here’s how you combat the elements to ensure your drone makes it back to you safely.

1. 1. Know Your Limits

      While knowing your personal limits is important, here we are referring to the operating limits of your aircraft.  While each type model will have its own limitations, most recreational drones are designed to operate safely between 32˚F – 104˚F (0˚C – 40˚C).  Some, like the DJI Inspire, are capable of going all the way down to 14˚F (-10˚C).  However, the gimbal/camera on that aircraft is only rated for 32˚F, so you might still have some issues if you go colder than that.  All that being said, let’s be honest…who wants to be running around outside when it’s 14˚F anyway?

   2. Keep an Eye On Your Battery

      OK, this is a big one because your battery is the component that will take the most significant hit from the cold weather.  The Lithium Ion Polymer (LiPo) batteries used by most drone manufacturers are great for a few reasons: they’re relatively light, power dense, and do a good job of holding onto power when on the shelf.  However, they tend to perform worse in the cold, so we have to give them a little extra love to ensure maximum performance.  For information about why they suffer in the cold, read below…otherwise skip this.

      You see, the electric current generated by a battery is produced when a connection is made between its positive and negative terminals.

      When the terminals are connected, a chemical reaction is initiated that generates electrons to supply the current of the battery. Lowering the temperature causes chemical reactions to proceed more slowly, so if a battery is used at a low temperature, less current is produced than at a higher temperature. As the batteries run down they quickly reach the point where they cannot deliver enough current to keep up with the demand.

      In summary: Warm batteries = GOOD / Cold batteries = BAD
      
      The good news is that there are steps you can take to ensure optimal battery performance in cold weather.

      The first thing you should do is keep your batteries warm.

      DJI offers battery warmers for its Phantom and Inspire series that will do a good job of keeping your batteries in the optimal temperature range all the way down to -4˚F (-20˚C).  Of course, that’s well below the published limits of the aircraft itself, while so your drone might freeze, but your battery will be nice and toasty.  At $20, these won’t necessarily break the bank, but if you’re cheap like me…there are other ways.

      Common sense would tell you if you have your vehicle around and it’s warm…keep them in there.  If not, put them in an internal pocket close to your body.  If you can’t do that, some people have reported success placing the batteries in a bag (or pocket) with a small hand warmer.  Wherever you decide to put it, just remember, the goal is to keep the battery above 41˚F (5˚C).  Most drones will allow you to check the temperature of your battery once the drone is powered on so it’s always good to give it a check once you spin up.  Most seasoned pilots recommend hovering at a low altitude for a minute or two so that your aircraft systems and battery have a chance to warm up a bit before you carry on with your flight.

      Even if you warm up the battery properly, the cold weather can still impact your flight time by a bit, so you should keep a close eye on your power levels, go easy on the throttle, and bring the A/C back right away if you start noticing anything abnormal.

   3. Watch Out for Ice

      Icing is a well-known enemy in the manned aviation world and can have disastrous effects on an aircraft of any size as it increases the weight of the aircraft and inhibits the wings (or rotors) from generating lift.  While this is a major factor for manned aircraft, current restrictions on IFR drone operations should help minimize the occurrence of ice.  That being said, it can happen to you, so it’s good to keep an eye out for symptoms of ice such as reduced throttle performance / reduced lift, imbalance of aircraft, abnormal flight controls, and uncontrolled descent.  While most icing tends to occur at temperatures between 0°C and -20°C (well below what you will probably be flying at), icing conditions can exist at temperatures above freezing, depending on the relative humidity and other factors.  For instance, if you are flying in cold, moist air like fog as seen in the video below your rotors can ice up pretty quickly.

      I’ve never personally tried it, but some people have reported success spraying WD-40 or windshield de-icer on the props to help minimize the accumulation of ice.