merlin Thats interesting you said photovoltaics with micro heat pumps, because on pg 17
For the employment in a flight altitude of 20km the extreme environmental condition, an air pressure must be considered of approximately 1/20 of the air pressure at ground level, temperatures around 216K as well as the radiation intensity risen by 340W/m2 at the ground to 1150W/m2 by the sun [81]. In reciprocal effect with the site conditions the sun exposure leads to large temperature differences and thus thermal Tensions between that the sun exposed surfaces and shade surfaces.
I haven't read anywhere so far that they would exploit this.
As far as energy storage, batteries are out.
(PEM) is gas cells conceivable.
But in the meantime LH2 with three individual Kryotanks, 3 Gas turbines and 3 generators, and 6 Siemens engine 1FT6086-8WK7 will be used.
LH2 2.1 mwh = 238 lbs. a few days supply will get your 9 days.
The energy surplus must be transferred to an energy storage with a capacity of 2.1 MWh.
