Formula: {Fuel_xi = LH2 (Liquid Hydrogen}

Liquid hydrogen (LH2) fuels Xi at remote theaters for agile, aggressive & autonomous manoeuvres.

Xi dimensions:
~ L_Xi = 231.648 cm - the length of the Xi
~ D_Xi = 33.538 cm - the diameter of Xi

The challenge is to fit the LH2 tank inside Xi and keep it light enough:
~ L_LH2Tank = 46.3 cm - the length of the LH2 tank
~ D_LH2Tank = 26.6 cm - the diameter of the LH2 tank
~ R_LH2Tank = 13.3 cm - the radius of the LH2 tank
~ V_LH2Tank = p × R_Tank² × L_Tank = 25 717 cm³ = ca. 25.0 liters = ca. 6.6 US gal - the volume size of the internal LH2 tank

Weigh of LH fuel fitting inside LH2 tank: - LH2 as a fuel is light for Xi
~ d_LH2 = 0.07 kg/l - the density of liquid hydrogen
~ w_LH2 = d_LH2 × V_LH2Tank = 1.75 kg = 3.85 lbs

Weigh of LH2 tank: - LH2 tank is not too heavy and thanks to new composite materials will be lighter
~ c_LH2 = 0.11 - LH2 mass presents typically 11% of the total mass of the LH2 tank
~ w_LH2 = c_LH2 × w_LH2Tank <=> w_LH2Tank = 15.9 kg = 35 lbs

Total Weigh penalty LH2: - not too bad and these figures are pessimistic, see XCopter
~ w_LH2Total = w_LH2 + w_LH2Tank = 17.66 kg = 38.85 lbs

Efficiency of LH2 as a fuel: - offers performance for aggressive and agile manoeuvres
~ b_LH2 = 4 - constant depicting the fact that four times more LH2 liters are needed compared to benzin
~ e_LH2 = 1.33 - constant depicting the fact that LH2 fuel is 1.33 times more efficient than benzin
~ E_LH2Tank = V_LH2Tank / b_LH2 × e_LH2 = 8.3 liter - the benzin energy provided by the main LH2 tank

Requirements for Xi: - are being met
~ Maximum_Flight_Time_xi
~ Maximum_Speed_xi
~ if Xi consumes LH2 50 l/h = 13.2 gallon/h, that equals to two LH2 tanks
~ above means that Xi can fly 100 kilometers in one hour (ca 60 miles/hour) with two tanks of LH2
~ due to it's aerodynamic shape Xi needs one external LH2 tank for one hour mission

Specifications:
~ Hydrogen power @Xi

Information:
~ LH2!

catch ~Fuel_XCopter ~Xi!