Formula: {Volume_Tank_XCopter = 100 000 cm³ = 100 liters = ca. 30 U.S. gallon}

Tank volume assumed for LH2:
~ V_LH2Tank = 100 000 cm³ = 100 liters

Weigh of LH fuel itself:
~ d_LH2 = 0.07 kg/l = 70 grams / liter - the density of liquid hydrogen
~ w_LH2 = d_LH2 × V_LH2Tank = 7.0 kg

Weigh of LH2 tank:
~ c_LH2 = 0.11 - LH2 mass presents typically 11% of the total mass of the LH2 tank
~ w_LH2 = 7.5 kg = c_LH2 × w_LH2Tank <=> w_LH2Tank = 68.18 kg

Total Weigh penalty LH2:
~ w_LH2Total = w_LH2 + w_LH2Tank = 75.18 kg

Efficiency of LH2 as a fuel:
~ b_LH2 = 4 - constant presenting the fact that four times more LH2 liters are needed compared to benzin
~ e_LH2 = 1.33 - constant presenting the fact that LH2 fuel is 1.33 times more efficient than benzin
~ E_LH2Tank = the energy one LH2 offers
~ E_LH2Tank = V_LH2Tank / b_LH2 × e_LH2 = 33.25 liter

100 liters LH2 provides:
~ assumption: consumption benzin 10l/100km <=> liquid hydrogen 40l/100km, speed 100 km/h
~ range /one hour = 100 km = 40l H2 <=> one tank of LH2 offers 250 km flight

catch ~Volume_Tank_Xi ~Tank_XCopter ~Fuel_XCopter ~XCopter!