Sizing of the Fuel Tanks
1. Tank Volume
The storage density for the fuel is .0708 tons per cubic meter. Therefore, the total volume needed is:
| Vol | = (264.276 mt)*(1/.0708 mt/m^3) |
| = 3732.71 m^3 |
The radius of the fuel tanks is set at 2.5 meters and the length is then computed.
| length | = (Vol/6)/(pi*r^2) | ||
| = (3732.71 m^3/6) / (pi*(2.5)^2) | = 31.68 meters |
The total volume is divided by six, because six fuel tanks are used.
2. Tank Thickness
A. Interstellar cruise phase
Newton's equation, F=ma, is used to find the forces on the fuel tanks during flight. The maximum force will occur when the acceleration is a maximum. This is when the mass is a minimum for a constant thrust problem. In our case, the minimum mass is:
| Mmin | = 2 fuel tanks + 6 straps + center section + engine + payload |
| = 89.345 metric tons |
Therefore,
| Amax | = Thrust/m |
| = 1.838e3 N / 89.345e3 kg | |
| = .021 m/s^2 |
The maximum force possible on the tanks could then be:
| Fmax | = (mass of fuel in tanks) * a |
| = 44.05e3 kg * .021 m/s^2 | |
| = 924.97 N |
A safety factor of 5 is now applied to find the design load.
| Fdes | = 5 * F |
| = 4.62 kN |
Next, the tank area that the force is acting on is found.
