Core Mass Subsystem

The core mass subsystem is responsible for calculating the mass properties of the aircraft. This includes the empty weight, fuel weight, payload weight, and other mass properties.

Note

This section is under further development.

FLOPS Based Mass Subsystem

FLOPS used a series of regressions and basic relations to estimate the weight of various transport aircraft components. The equations used are well-documented and freely available[1]. Aviary uses mass instead of weight, which is a subtle but important change to be aware of.

Fuel_Capacity

The Fuel Capacity Group contains 4 subsystems:

1. Wing Fuel Capacity

   Aviary assumes that the wing volume can be approximated as a rectangular based pyramid, and that the available volume for fuel is a user specified fraction of this theoretcial volume (Aircraft.Fuel.WING_FUEL_FRACTION). The derivation of Aviary’s theoretical volume calculation is included below:

   

   Aviary then converts the volume to a capacity (lbm) using the user specified fuel density (Aircraft.Fuel.DENSITY).

2. Fuselage Fuel Capacity

   Fusleage Fuel Capacity = Total Fuel Capacity - Wing Fuel Capacity

3. Auxiliary Fuel capacity

   Auxiliary Fuel Capacity = Total Fuel Capacity - Wing Fuel Capacity - Fuselage Fuel Capacity

4. Total Fuel Capacity

   Total Fuel Capacity = Wing Fuel Capacity + Fuselage Fuel Capacity + Auxiliary Fuel Capacity

It is possible for Aviary to calculate negative fuel capacities depending on user overrides and the input wing geometry. These situations are not currently flagged to the user.

References

For additional information, please see the following resources:

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[1]

The Flight Optimization System Weights Estimation Method. NASA Technology Transfer Program. URL: https://ntrs.nasa.gov/citations/20170005851