Although the estimated power of the Lilim jet's power-plant is 144 kW, we further assume that the AG-EVTOL prototype based on the Lilim jet will be equipped with a 200 kW AG-gas turbine generator. Greater power will allow to boost the prototype's cruise speed. The weight and hovering power of the AG-EVTOL prototype are assumed to be the same as those of the Lilium jet, 1,700 kg and 650 kW, respectively. The prototype's AG-gas turbine generator will be paired with a graphene ultra-capacitors pack having a nominal C-rate of 30 and gravimetric energy of 60 Wh/kg. Accordingly, the energy and weight of the pack will be [(650-200)/30], i.e., around 15 kWh, and [15/0.06], i.e., 250 kg.

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In case the AG-gas turbine generator malfunctions during the flight, the 15 kWh ultra-capacitor pack will provide enough power and energy to safely land the air-vehicle because the pack may, for a limited period of time, provide 50% greater power than that characterized by its nominal C-rate.    

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Although contemporary gas turbine technologies allow for keeping the weight of a 200 kW gas turbine generator with 30% efficiency beyond 350 kg, including the weight of fuel and water, pumps and pipes, a ceramic high-temperature heat exchanger, if durability, reliability, and low cost are prioritized rather then thermal efficiency. For an externally fired gas turbine generator, the overall efficiency of the prototype's power-plant is estimated at [30*2.5*0.8], i.e., 60%, where factor 0.8 accounts for high-temperature heat exchanger efficiency, which is expected to be relatively low due to gravimetric and volumetric limitations in aerial applications.    

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If the prototype's cruise power is 200 kW, its cruise speed is conservatively estimated at [188*sqrt(200/144)], i.e., around 220 mph. Accordingly, flying a 600 mi distance in [600/220], i.e., 2.7 hours, will require [((200/0.6)/33.7)*2.75*2.7], i.e., 73 kg of hydrocarbon fuel, where 33.7 kWh is the thermal energy content of a gallon of hydrocarbon fuel; 2.75 kg is the weight of a gallon of fuel; 2.7 hours is the flight time. The weight of the fuel tank is estimated at 17 kg. The weight of the power system and fuel, including fuel reserve (10 kg), is estimated at [73+17+10], i.e., 100 kg. The weight of the water system and water, or alternatively, water condenser, are estimated at 100 kg.

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Suppose the weight of power electronics will not exceed 100 kg (energy recuperation mode is not implemented). In that case, the weight of the power-plant, fuel system, and fuel will not exceed [250+350+100+100+100], i.e., 900 kg, i.e., the estimated weight of Lilim jet's authentic battery.