systems.md



Implemented Aircraft System Models
These system models are relevant if you choose to use the standard strategy of systems design.

ATA 21: Environmental Control System
The environmental control system model implemented is powered by electric power and bleed air from the engines.
Methods
The power required by the environmental control system is calculated based on the heat loads of all systems, the heat from the sun and from the passengers. The ECO-Mode allows to reduce the required bleed air by 25%. Air conditioning is switched off during takeoff.
The mass of the ECS depends on the bleed air mass flow in the design point. Calculation method from LTH and Howe. The mass is broken down into the components ducts, air conditioning pack, outlet, ram inlet, vents, and misc. according to factors determined by Koeppen¹.
The CoG of the ECS is determined with the assumption that its located in the belly fairing.
Required Input Parameters

Airflow per PAX [kg/s]
Recirculation [-]: percentage of cabin air that is reused (0.0 - 1.0)
Heat Convection [W/(m^2*K)]: heat convection over aircraft skin (based on Airbus air conditioning system design)
Cabin Temperature [K]
Specific Heat Flow from Sun [W/m^2]
Window Area [m^2]: Area of a single window
Heat per PAX [W]: heat emitted per person
Heat per Light Length [W/m]
Efficiency Factor of the Air Conditioning Pack [-]
Heat Capacity Air [J/(kg*K)]
Off Take Off: Switch to turn of ACP during take off
ECO Mode: Switch for ECO Mode reduces bleed air requirement by 25%


ATA 24: Electric System
Methods
CheckUserInput() checks if generator sources exist.
The required power of the electric system is the power lost through inefficiencies. The efficiency factor for the electric system and for the generators are considered.
The mass calculation method from Steinke is based on the maximum required electric power and the cable length. The cable length is defined as 2*fuselage length (main bus from front to back, two bus systems) + connection of the engines to the avionics bay. A factor is applied to the mass depending on the design range of the aircraft (short or long range).
Required Input Parameters

Efficiency Factor [-]
Maximum Relative Power [-]: ratio of maximum permanent power and maximum required power of all generators
Specific Cable Mass [kg/m]
Number of Electric Circuits [-]
Number of Generators [-]
For each Generator:

name
type (IDG, APUG, ...)
source type (hydraulic, engine, APU)
source ID
efficiency
operation factor (share of total power in normal operation)


ATA 25: Furnishing System
Furnishing system includes the power required for the galleys and the inflight entertainment system (IFE). The mass of all furnishing is calculated in fuselage design and read from the aircraft exchange file.
Methods
Power calculation is done based on user inputs.
!!! important
Because the mass of furnishing items is already calculated in fuselage_design, it is not changed in systems_design and there is no scaling factor available in systems_design to adapt this mass. If you wish to make adaptions, you can do this in fuselage_design.
Required Input Parameters

Galley Load Fraction during Takeoff [-]:
Electric Load Analysis for A320 suggest a value of 0.2¹


Galley Load Fraction during Cruise [-]:
Electric Load Analysis for A320 suggest a value of 0.7¹

Galley Load Fraction during Descent [-]:
Electric Load Analysis for A320 suggest a value of 0.2¹

Galley Location [m]
Non Personal IFE Power [W]: General power for IFE
Personal IFE Power [W]: Power for IFE per PAX
Personal IFE Load Fraction Climb [-]:
Electric Load Analysis for A320 suggest a value of 0.58¹

Personal IFE Load Fraction Cruise [-]:
Electric Load Analysis for A320 suggest a value of 1¹

Personal IFE Load Fraction Descent [-]:
Electric Load Analysis for A320 suggest a value of 0.5¹


ATA 26: Fire Protectrion System
Does not require power!
Methods
Mass calculation is based on propulsion type and MTOM (Torenbeek Tab. 8-12).
Required Input Parameters