Solar powered plane without batteries

Could an unmanned solar plane go not only above the clouds, but also so fast that it always is in the day-side of the planet?

A solar plane flying above the clouds receives sunlight $12$ hours per day, but there is a need for batteries to fly in the night. Such plane could fly continuously for decades without even fearing the degradation of batteries and it could be very much lighter given that batteries weight approximately $\frac{1}{4}$ of solar impulse

From a basic analysis of the problem I see these issues:

• It would need to go around the world in $24$ hours, and given a diameter of $40000$ kilometres for the world, we have a need of $\frac{40000~\text{km}}{24~\text{h}} = 1667~\frac{\text{km}}{\text{h}} = 463~\frac{\text{m}}{\text{s}}$

  Going so fast (even supersonic) will require a lot of energy, thus a lot of solar panels thus a lot of weight, that will require even more energy...

• Electric means that it must use propellers, propellers require dense air to be efficient, this source gives the density a very high importance putting it squared in the equation for thrust.

  Solar means that it must go high (over the clouds) and high means sparse air.

• Some clouds are just too high to go over (the highest clouds in Earth's atmosphere, located in the mesosphere at altitudes of around $76$ to $85$ kilometres - credit Wikipedia), for these elusive maneuvers (going around them) will be needed.

Could these issues be circumvented to create a solar plane without batteries capable of continuous flight?

posted about 8 years ago

Caridorc‭

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