Sweden in January is very cold! The coldest I had flown in prior to this shoot was a frosty english morning, barely dropping below 0°C. Sweden was nearing -20°C (thats -4°F for you Americans). I'm a guy that likes to be prepared but living in the comparatively toasty 10°c Britain, it was hard to comprehend how -20°C would feel so knowing how to prepare was difficult. In this post i’ll take you through how I prepped for this shoot and the lessons I learnt.
In short, these are the key things that kept me and the drone going in the coldest of conditions:
DJI Battery Heaters
Electric Heat Blanket
Chemical Hand Warmers
A Cool Box
Hot Water Bottles
Transmitter Glove
Warm Clothing
Food & Drink
As a general rule of thumb I needed to keep both myself and the drone in the warmth of the car or building for as long as possible and only get the kit out in the elements when necessary.
Keeping the Aircraft Batteries Warm
Keeping the drone batteries warm was my key focus as I knew if they got cold, flight times would be reduced dramatically and may not even allow the drone to take off at all.
To start with, I had several Inspire Battery Warmers that I'd use for the two next batteries I'd plan to use. These heaters are rated to work in ambient temperatures down -20°C but I remained sceptical of that claim. These would (on paper) heat the battery to about 23°C.
I then put the batteries in a (very fashionable) cool box which acted as a thermal insulation box to retain as much heat emitted as possible.
Along with the batteries in the cool box I also added two hot water bottles, several extra layers of ThermaWrap and an electric heat blanket.
The blanket runs off 12V which can either be powered from a mains socket, car cigarette lighter or a 3 cell LiPo battery. Having these options allowed me to heat the blanket wherever I was with whatever power source I had available.
iPad Batteries Suck
So I had the drone batteries all snuggled up in the warmth of the cool box but I hadn't given any thought to the iPads internal battery. The majority of iPads are made from aluminium which in such cold conditions feels like holding an ice cube. This had the knock on effect of freezing the Lithium Ion battery inside. One of the iPads went from reading 100% to 0% in just 40 minutes.
My solution to this? Hand warmers. Tape a couple of hand warmers to the back of each iPad. These cheap, £1 warmers stayed toasty for about 6 hours.
Aircraft Icing
I had never experienced ice forming on the a drone before and in these conditions it was definitely in the forefront of my mind, checking overtime before and after every flight. I learnt that if there was any moisture in the air at those temperatures, you'd get ice would form. Thankfully the inspire propellers are made from a plastic composite which meant ice didn't form on them - this would have been a concern as it could seriously effect lift and strength of the propellers. Having said that, the carbon fibre arms did get a nice icey frosting!
One other thing I noticed was that although the grease on the worm drive didn't freeze, it did stiffen up, forcing the servo to work harder. If it did freeze up mid flight and the legs were raised, my contingency procedure was to do a catch land and wait for it to defrost.
Keeping Ourselves Warm
I was warned before heading out that if you don't take care of yourself and keep warm, it's likely that you'll give up before the drone does. Snuggled up in about 5 layers of clothes and plenty of hand warmers did the job.
Also, staying hydrated is super important (as always) but easy to do when it's cold without realising.
Would I Do It Again?
Anyday! It's always fun flying in challenging conditions and there are always lessons to be learnt. Although DJI don't recommend flying in temperatures less than -10°C, the trusty Inspire held up very well.
Big shout out to the team for making this shoot possible and so enjoyable.
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