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Tony's Intertwingled Memex • Reference Manual

Aerospace Fuel Tank Center of Mass and Slosh Baffle (Aerospace & Mechanical Engineering)

Formulas & Definitions

An aerospace structural dynamics engineer at the UNLV Howard R. Hughes College of Engineering is designing a lightweight titanium fuel cell integrated into the wingtip structure of an autonomous reconnaissance aircraft.

The interior reservoir of the fuel cell is bounded by the three coordinate planes x=0x = 0x=0, y=0y = 0y=0, z=0z = 0z=0 and the upper inclined wing-skin aerodynamic fairing plane:

x+y+z=1x + y + z = 1x+y+z=1
where all coordinate dimensions are measured in meters (m\text{m}m).

Due to internal anti-slosh porous baffle foam and fuel pressurization, the effective mass density ρ(x,y,z)\rho(x, y, z)ρ(x,y,z) within the cell increases with vertical height according to:

ρ(x,y,z)=ρ0zwhere ρ0=120 kg/m3\rho(x, y, z) = \rho_0 z \quad \text{where } \rho_0 = 120\text{ kg/m}^3ρ(x,y,z)=ρ0​zwhere ρ0​=120 kg/m3

To evaluate wing aeroelastic flutter and provide precise mass properties for the flight-control autopilot:

  1. State the general Type I boundary equations for the tetrahedral solid region EEE in the order dz dy dxdz \, dy \, dxdzdydx.
  2. Formulate and evaluate the triple integral for the geometric volume V(E)=∭E1 dVV(E) = \iiint_E 1 \, dVV(E)=∭E​1dV in cubic meters (m3\text{m}^3m3).
  3. Formulate and evaluate the triple integral for the total fuel mass M=∭Eρ(x,y,z) dVM = \iiint_E \rho(x, y, z) \, dVM=∭E​ρ(x,y,z)dV in kilograms (kg\text{kg}kg).
  4. Evaluate the first moment of mass about the xyxyxy-plane, Mxy=∭Ezρ(x,y,z) dVM_{xy} = \iiint_E z \rho(x, y, z) \, dVMxy​=∭E​zρ(x,y,z)dV, and determine the vertical center of mass coordinate zˉ=MxyM\bar{z} = \frac{M_{xy}}{M}zˉ=MMxy​​ in meters (m\text{m}m).
  5. Explain why tracking shifts in the vertical center of mass zˉ\bar{z}zˉ as fuel drains is critical for preventing wingtip stall and maintaining roll trim stability during high-ggg maneuvers.