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Norwegian-American Scientific Traverse of East Antarctica

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Cold creatures

by Svein Henriksen and Stein Tronstad — sist endret 22.02.2009 - 23:04

Most humans adapt well to the altitudes and the temperatures we are working in, but the same cannot be said for our ”sled dogs”. The tracked vehicles and all other mechanical equipment require several adjustments and constant attention to work well on the Antarctic plateau.

Location: ”NUS08-7”, 74º 7’ S, 1º 36’ E, 2700 metres a.s.l.
Weather: All clear, -24/-37 C, wind 3 kts

With the altitude follows low air pressure and a relative lack of oxygen, giving the engines a significant reduction in power output and less efficient combustion.  There are no straightforward solutions to this problem.  Modern diesel engines are computerized, and in this case the computer’s response to the lack of oxygen is to reduce the amount of fuel injected.  The engine output spirals down, precisely when we need it to go up.  The solution has been to reprogram the computers and to short-circuit the air pressure sensor, making the engines “believe” that they are running at sea level.

The cold is a more comprehensive problem, affecting virtually everything mechanical.  Meltwater running off hot panels, condensation in fuel tanks or hoses, or any other water seeping into inconvenient places – all of it will freeze and stop parts from running or liquids or air from passing.  Batteries will also freeze if not properly maintained.  A fully charged vehicle battery can survive a solid –70º C; but if completely discharged it will freeze up already at –10º C.  Fuel, oil and lubricants loose viscosity and get thicker, metal and plastic components get brittle, materials contract, fittings loosen, and vibrations increase.  In normal temperatures electrical cords will coil easily, below -30 C they get rigid – and instead of a coil we may end up with a pile of broken segments.

Almost any mechanical part will break more easily in the cold, everything is harder to move or get moving, and any engine or Webasto heater will be difficult of impossible to start without advance preparations.  The vehicle wheels pose a good example: At +20º C the wheel will roll freely on its bearings, and a light touch will set it moving.  At –40º C we will have to apply a force of about 15 kg to be able to turn the wheel at all.  Our TL-6 vehicles have 24 wheels each, so at these temperatures it takes a lot of power just to get the wheels rolling – let alone move the vehicle.

How are we dealing with all this?  First of all, the vehicles, generators and other machinery is specially prepared.  All engines have electric block heaters and fuel-burning Webasto heaters.  Separate heaters are mounted on the fuel filters, the hydraulic and engine oil systems.  Some hydraulic cylinders are also separately heated.  Cords are made of special materials, and coolant liquids are chemically altered to lower the freezing point.

Secondly, we have it in our daily routines to be prepared. A generator is always kept running throughout the night, delivering electricity to heaters and battery chargers. When we start driving in the morning, it is never just a matter of turning the key and getting off.  The Webasto engine heaters are usually started at 6 am and allowed to run for an hour before we start the engines themselves.  After another hour of idling, the engines are usually warm enough to start driving – but even then it’s done cautiously.  We start in 1st gear, go to 2nd after a few minutes, and keep going very slowly to make sure all systems have a good working temperature before we finally increase to normal driving speed after about 20 minutes.  Thus it takes us nearly 2,5 hours to get the vehicles going at full speed.

The key is to maintain good margins and always take precautions.  Fuel tanks are topped up before nightfall, to avoid humid air and water condensation inside them.  Batteries are always kept fully charged.  Electrical cables are always handled very carefully, and never when connected to power.  Heat and energy conservation is always on our minds, and thus we are still going strong, at 2700 meters of altitude and with night temperatures dropping well below -40º C.


8.feb

Andreas with a cord that probably shouldn’t be coiled right now.  Photo: Stein Tronstad/NPI

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