Formula: {Fuel_XCopter = (petrol,diesel,bio-diesel,special fuel,gas}

Hydrogen stored in metal hybrides (MH2) and fuel cells are being used to power electric engines of UAV helicopters.
Liquid hydrogen (LH2) has been used to power some concepts cars, but no data was found about LH2 as a fuel to UAV helicopters.

LH2 as a fuel:
~ d_LH2 = 0.07 kg/l - the density of liquid hydrogen
~ c_LH2 = 0.11 - LH2 mass presents typically 11% of the total mass of the LH2 tank
~ b_LH2 = 4 - constant presenting measurements indicating that four times more LH2 liters are needed compared to benzin
~ e_LH2 = 1.33 - constant presenting measurements indicating that LH2 as a fuel is 1.33 times more efficient than benzin

MH2 as partner for LH2:
~ hydrogen stored in metal hybrides
~ provides electricity to vehicle systems allowing engine to use liquid hydrogen just for running engine
~ saves LH2 and allows vehicle to operate for example electric systems, sensors and cameras without consuming liquid fuel LH2

BMW745h hybrid car is based on the following features:

BMW745h Tanksystem:
~ V_H2tank = 140 l - Kryotank
~ V_Benzintank = 88 l - Benzintank
~ V_Totaltank = V_Benzintank + V_Kryotank = 228 l = 228 000 cm³ = 60 gallon (U.S)

BMW745h / Volume of LH2 tank
~ V_H2tank = 140 l = 37 gallon

BMW745h / Weigh of LH2 tank
~ W_H2tank = 75 kg = 165 lbs (not specified in detailed, assumed here that it is the total weigh of liquid hydrogen tank)
~ c_LH2 × 75 kg = 8.25 kg LH2 = 8.25 / d_LH2 = 117.86 liters H2 - differs slightly
~ 75 kg / 140 l = 0.536 kg/l weigh penalty of LH2 - tank is big but not too heavy because LH2 is not heavy itself, just takes space

BMW745h Energy inside LH2 tank:
~ E_tank = E_40lgasoline - the energy equivalent in benzin
~ this would give efficiency number 3.5 compared to benzin, which is less than b_LH2 above

BMW745h Fuel efficiency:
~ 10 km per gasoline liter = 100 km per 10 liter (assumed to be LH2)
~ D_tank = 10 km/l × 40 gasoline l = 400 km - a cruising range distance of 400 km in one hour

BMW745h running on hydrogen:
~ HP_BMW745h = 184 horsepower
~ S_BMW745h = 133 mph = 214 km/h - a top speed
~ R_LH2 cruising range is 190 miles = 305 km

BMW745h Runnign on both fuels:
~ 400-mile range of the normal fuel tank of 88l <=> 22l / 100 miles = 161km <=> 13.66 l/100km consumtion of benzin
~ 200-mile range of LH2 with 140-litre LH2 tank <=> 70l/100 miles <=> 43.48 l /100km consumtion of LH2
~ 600 miles between fill-ups

BMW745h Engine running on LH2:
~ 12-cylinder engine develops 204 horsepower
~ tops 100 km/h in 9.6-seconds
~ is capable of a top speed of 226 km/h
~ 140-litre cryogenic hydrogen tank gives a range of 350 km = 40 H2 liters/100 km

BMW745h Engine:
~ Engine Configuration: V
~ Cylinders: 8
~ Aspiration/Induction: Normal
~ Displacement: 4.40 L | 268.5 cu in. | 4400.7 cc.
~ Valvetrain: DOHC
~ Horsepower: 284 BHP (209 KW)
~ Torque: 295 Ft-Lbs (400 NM)
~ HP to Weight Ratio: 15.0 LB / HP
~ HP / Liter: 64.5 BHP / Liter


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