AIRCRAFT DESIGN IN SYSTEM MODELER

Niko Erä-Esko, Wolfram MathCore

(RowDefault[, (Spacer1), , (Spacer1), ])  #WolframTechConf

ABSTRACT

When developing a new aircraft, there are many different subcontractors involved. Each subcontractor has the responsibility for a specific part of the aircraft. For instance, Boeing 787’s wing tips are subcontracted to KAL-ASD in Busan South Korea, the forward fuselage to Spirit, Wichita, Kansas, the cargo access doors to Saab, Linköping, Sweden, and so on. But how is each part tested before all the rest is developed (and assembled)?

About a year ago we partnered with Saab Aeronautics to develop a new Aircraft modeling library, that would make it possible to test an aircraft at an early design stage. This has resulted in the new, soon to be released, Aircraft library.

Why are aircraft designers obsessed about weight?

Example: How does the amount of carried fuel affect the fuel consumption itself?

3 h 15 min flight with Boeing 737-800

fuelCons=SystemModelParametricSimulate["FuelingAircraft","boeing737800.propulsion.energyStorage.mConsFuel",{"initialMfuel"}];
totalFuel=SystemModelParametricSimulate["FuelingAircraft","boeing737800.propulsion.energyStorage.mEtot",{"initialMfuel"}];
Plot[Evaluate[Table[totalFuel[initialMfuel][t*3600],{initialMfuel,5000,20000,5000}]],{t,0,3.25},PlotRange->All,AxesLabel->{"Time [h]","Mass [kg]"},PlotLegends->{"5000 kg", "10,000 kg","15,000 kg","20,000 kg"}]
Plot[Evaluate[Table[fuelCons[initialMfuel][t*3600],{initialMfuel,5000,20000,5000}]],{t,0,3.25},PlotRange->All,AxesLabel->{"Time [h]","Mass [kg]"},PlotLegends->{"5000 kg", "10,000 kg","15,000 kg","20,000 kg"}]

Consumed fuel ranges from 5,000 kg to 6,200 kg (10,900 lb to 13,700 lb)

Had the weight reduction been done elsewhere, the need for fuel would have decreased anyways leading to further weight reduction

Modeling the Flight Mechanics

The Wolfram System Modeler is a powerful tool to model:

The aerodynamic forces locally on each surface of the aircraft

The forces and torques due to the aircraft's mass properties

Consequently, the aircraft’s motion through air can be modeled and simulated as a 6DOF flight mechanics model

Motivation

Why involving 6DOF flight mechanics model with simulation in aircraft conceptual design is beneficial?

Enables quick testing of the aircraft design for any flight trajectory with high fidelity

Early testing can be done in one single tool which derives aircraft properties from the properties that are available at the conceptual design stage

How it works?

Autopilot

The autopilot translates the the commands that describe the desired flight trajectory into aircraft control actuator commands

Entering the aircraft design parameters

In early design stage, the specific properties such as the total lift- and drag coeffiecients and the aircraft mass properties are not known

Empirical relationships are used to estimate their values from parameters that are easier to establish

Estimation of aerodynamic properties

Only the 2D airfoil properties used in different surfaces and some key dimensions of the aircraft are required as inputs from the aircraft design

Together with Mach number and Reynolds Number the aerodynamic properties of the entire aircraft are estimated by using empirical relations such that the air compressibility effects are also considered

Estimation of mass properties

The aircraft mass, center of gravity location and inertia tensor without the effect from fuel mass are estimated by empirical relations from aircraft geometry, some key design variables and the engine properties

Empirical relations are also used to estimate the variable mass properties of the fuel inside the tanks

The engine models are used to calculate the fuel mass flow

Model for electric powertrain with constant mass is also included in the library

All weight estimations can be bypassed and it is possible to enter a known mass property of a specific component or the entire aircraft instead

Example: Resizing Boeing 757-300

Redesign of Boeing 757-300 with newer and lighter composite materials

The exact B757-300 parameters and design variables were entered into the model with the exception of using the composite materials

Source: Glenn Beltz from Goleta, USA, CC BY 2.0, via Wikimedia Commons

A flight mission that the aircraft design need to carry out was generated

Here, the flight data of a real transatlantic flight from New York to London and further to Amsterdam (for the purpose of simulating a flight to a diversion airport) was used

An iterative process was followed, where:

The engine are resized to provide enough thrust for the flight mission

The tanks are resized to have enough fuel

The initial design maximum take-off mass converges with the estimated mass

The fulfillment of the set constraints on load factor and maximum dynamic pressure are checked

Eventually, the maximum take-off mass was reduced from 122,920 kg to 85,930 kg (270,992 lb to 189,443 lb)

Conclusions

6DOF flight mechanics model brings a valuable addition to aircraft conceptual design for validating the performance of the aircraft design

Enables working with multiple disciplines with one tool

The modularity of the library enables adding more disciplines to the model, aeroelasticity, turbulence etc., or to enhance the fidelity of the existing disciplines with ease.

System Modeler at WTC

System Modeler agenda at WTC 2022. All times in CST

Wednesday

10:30 - 10:55 am Green Energy Modeling

10:55 - 11:20 am Aircraft Design in System Modeler

11:00 - 12:00 pm Meetup: Engineering Education

02:45 - 03:45 pm Office Hour: System Modeling

04:30 - 05:00 pm Model Transformation for Smart Grid Applications

Thursday

09:00 - 09:30 am Extreme Citizen Science—Learning Enabled with Computational Essays

01:00 - 01:25 am New in System Modeler

01:25 - 01:50 am Model Predictive Control

01:50 - 02:15 am Neural Networks in System Models

Friday

09:30 - 10:30 am Meetup: Virtual Labs in Education

05:30 - 05:30 pm Cambodia Wolfram Student Stars! Mathematica, Arduino, Raspberry Pi