For this last version of the hydrogen-fueled design is important to argue that the basic require-ments stated at the beginning of this chapter, are not fulfilled at all. This fact comes from the necessity of a higher length of the fuselage, so in some cases as it has been seen the length of the A321 is not enough for the mission. In the first case for the A321-HS the solution adopted was to stretch the fuselage more than the original dimensions of the A321, in the second case the version A321-HW, the solution was to maintain the original dimensions of the A321 and use the fuel above for filling two new tanks installed on the wings of the original aircraft.
For this last case the solution of the fuselage length is to maintain the original A321, but the design starts with another version which is the A319-100. This aircraft also belongs to the A320 family of Airbus, but the number of passengers is reduced to 156 in order to use a model available in the market at the moment. For this reason the requirements setted in table 6.1 are not fulfilled at all, because the number of passengers is lower than in the original A320, but for being able to compare with the original version, the total mass of payload,mPLis maintained to his original value of 19.3 t, even if the original number of passengers is reduced, the A319-100 is stretched to the dimensions of the A321-100 which is about 10.7 m larger. The necessary mass of payload above is filled into the cargo volume and will be 2232 kg more for the cargo mass.
The tanks are filled into the fuselage in the same way than the previous two hydrogen-fueled versions, using the length above the original dimensions to insert the new tanks in the two parts of the fuselage. According to Brewer 1991 for a new design of a hydrogen-fueled aircraft, using the solution of a stretched fuselage, with the tanks filled inside the fuselage, the optimum configuration in terms of C.G control and structural behaviour is to design the aircraft in a way such that the total amount of the increased weight of the system (tank and fuel) is 60 % for the back part and 40 % on the rear part as it is done in the correspondent modified OPerA for this version and for the A321-HS where the tanks are installed as well into the correspondent fuselage section.
The A321-H19 follows the same philosophy respecting the fuel tanks which are installed in pairs into the two parts of the fuselage. For the lower backward tank a length of 5.5 m is required using a part for the space for the cargo, and carrying almost 1280 kg ofLH2. The details of the lengths and the mass of fuel are collected in table 6.8.
Table 6.8:Details of the tanks for the A321-H19
Length [m] Mass of tank [kg] Mass of fuel [kg]
Rear upper tank 4.36 612.5 1685.2
Rear lower tank 4.36 262.5 1017.7
Back upper tank 6.54 1312.5 2462.9
Back lower tank 5.47 329.5 1277
Total [kg] 2517 6442.8
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Due to the fact that the mission is the same and mass of fuel required is not so different between the three versions, the total mass of the tanks is almost the same and depending of the version, it will determine more the performance of the aircraft, being an important influence for the total mOE, which in turn influences themMTO, and the final features of the aircraft.
The final design and configuration for this version is closed to the A321-HS, but in this case the length of the fuselage is lower and the length of the fuel tanks are higher. This difference can be seen in Figure 6.10, where the fuselage and tanks of both versions are quiet different.
Figure 6.10 Fuselage comparison between A321-HS and A321-H19
Because this version reduced the number of passengers till 156 theDOCwill rise considerably since it is calculated per passenger and as it is shown in table 6.9 is up to 35 % higher and 31
% for the A321-H19O according tu AEA, being even higher the increase according to TUB, nevertheless it can be seen better results when the optimizer is performed. On the other hand, the maximum take-off mass of the aircraft has been reduced in this case by almost 2 % because the fuel mass is reduced more than the increase of the operational empty mass which is raised to the value of 12.5 % and 10.5 % for the optimized version.
For the optimization of the A321-H19O, the methodology followed is the same, not touching the cabin parameters even if the number of passengers is lower, the comparisons with the other versions is realistic since the payload mass is the same and the aircraft is designed in the same point of the PL-R diagram atRMPL. The thrust required for the engines is also lower for both versions as well as theSFCalmost in the same proportions than the other versions.
The results in terms of performance and efficiency are interesting because in this case the orig-inal configuration and dimensions of the the A321-100 are almost the same excepting the nec-essary changes for the fuel system and tanks installation typical of a hydrogen-fueled aircraft design, however the negative point is the fact that the number of passengers is decreased and this can be a negative influence for the industry when deciding to make the final step.
Table 6.9:Results and comparison with A320-200 from OPerA for A321-H19 and A321-H19O Parameter A321-H19 Variation (A320) A321-H19O Variation (A320)
mMTO [kg] 70916 -1.9 69815 -3.4
mOE [kg] 45208 +12.5 44426 +10.5
mF [kg] 6443 -49.7 6124 -52.2
DOC(AEA) [e/NM/t] 1.78 +34.9 1.73 +31
DOC(TUB) [e/NM/t] 1.61 +39.8 1.56 +36
lF [m] 46.2 +20.5 46.2 +20.5
SW[m2] 126.5 +5.1 120 +0.1
bW,geo[m] 34.7 +2.5 36.0 +6.5
AW,e f f 9.5 0 11.9 +25.3
ϕ25 [◦] 25 0 18.84 -24.6
λ 0.21 0 0.14 -34.3
Emax 17.6 +0.3 19.6 +11.9
TTO[kN] 100.2 -8.4 87.3 -20.2
BPR 6 0 8.2 +36.8
SFC[kg/N/s] 5.82E-06 -64.8 5.75E-06 -65.2
hCR[ft] 37676 -3.1 31583 -18.8
mMTO/SW[kg/m2] 560.7 -6.6 579.6 -3.5
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