Then they fly out north for another couple of hours to drop off fuel at a fuel "cache" and then fly back again - and that's all before they can start to head out to us.

More efficient internal-combustion engines will wring out mileage from every drop of fuel, and hybrid powertrains will combine an electric motor with a conventional engine.

In order to build the DPF pressure drop model based on air intake flow, DPF bed temperature, soot and fuel charge, the paper has carried out a series of tests, collected a mass of data.