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Hydrogen PEM fuel cells offer roughly how much energy-density advantage over a Li-Po battery, and what does this mean for flight time?

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1. Hydrogen PEM fuel cells offer roughly how much energy-density advantage over a Li-Po battery, and what does this mean for flight time?

Up to ~150x energy density, extending flight from minutes to hours

About 25 days of continuous flight regardless of payload

Roughly double the energy density, adding 10 extra minutes

No real advantage, just lower weight

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