Originally Posted by
Big Pistons Forever
Guys help out this math challenged Biology major. So 76 tonnes = 167,000 lbs so even with a reasonable 10 lbs/hp power to weight ratio that is in round numbers 16,000 hp or 12,000kw of thrust. So assume 400 kph, 800 km no reserve requires a battery that can produce 24,000kw/ hr.
Is that even remotely possible even if the battery weighs 35 Tonnes ?
Finally how many electric cars can you make with 35 Tonnes worth of batteries?
I will stay in metric for my sanity.
They do charge and discharge rate considerations in the paper, and it all looks plausible to me. Let us try some
very crude ratio checks.
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There are 8 x 1.4MW electric motors on this design (continuous rating), which looks about right, so 11.2MW in toto.
For the 2nd gen aircraft they are using 440Wh/kg at pack level (table 3). So 35,000 x 440 = 15,400 kWh = 15.4 MWh
So at full throttle these motors could drain that pack in just over 1 hour (1.35h more precisely). That is entirely plausible and is similar to running a BEV automotive at max throttle.
For comparison a Tesla Model 3 has approx 82kWh and the motor in one variant is 137 kW, so at max power that could empty its battery in half an hour (0.59h).
So the aircraft is treating its batteries more gently than a typical automotive.
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15,400 kWh / 82 kWh = 188 cars worth of batteries.
For a 90 seater aircraft that looks about right, given the typical vehical seat occupancy fraction, and typical aircraft seat occupancy fraction.