September 1, 2023, ©. Leeham News: We described the Preliminary design phase of an airliner development program last week. One could say this was the classical way that aircraft projects conduct Preliminary design.
There is a different way that Conceptual and Preliminary design can be run. It’s more along the lines of pre-development of functions, as a reader commented on two articles back.
Alternative Conceptual and Preliminary design
The gaps between new airliner projects the size we are looking at, Heart of the Market or Widebody, are going from 10 to 15 years historically to decades without OEMs like Airbus or Boeing developing a new generation of airliners.
Historically the time between aircraft projects was spent exploring new technologies and their suitability in a next-generation plane project.
However, the extended time between projects and the new possibilities to make detailed digital models of functions and systems makes it possible to develop, test, and then prepare a detailed digital model of candidate functions and systems that can be part of a next-generation airplane family.
Such work can be decoupled from actual airliner projects and will prepare a library of “pre-developed” solutions and systems that can be used in the project.
The Conceptual phase is still preparing different candidates to fulfill the Marketing and Sales department’s specifications for what the airliner family shall achieve in the market. The Preliminary design phase now expands in scope and OEM workforce, Figure 1.
The preliminary design phase now has the overall architecture of most systems settled, with detailed digital models describing their functionality, performance, and installation consequences (mass, space, hydraulic and electric power, cooling, wiring /piping requirements).
The Preliminary design still sizes the overall aircraft, its aerodynamics, forces, moments, etc., but the availability of detailed digital models of virtually all systems means these can be sized and scaled to fit the aircraft.
Out comes a definition of the aircraft, which is much deeper and more correct as systems have now influenced the overall design of the aircraft with their volume, mass, and power requirements.
The detailed studies with CFD and windtunnel tests for aero and FEM runs for structure are still made but now have more correct systems simulations as inputs.
Ultimately, the digital models of different parts of the aircraft can be put together to generate a “Digital Twin” version of the aircraft, giving a much deeper, more detailed definition of the aircraft to the next phase, which is Detailed design.
With a well-designed Digital Twin, it should also be possible to do airport turnaround and mission simulations that can test the limits of what the design can do. The demands of this aircraft type will be shorter turnaround times with still larger passenger, bags, and cargo streams on and off the aircraft.
Different solutions in the cabin and for systems give different results. It can influence design trades and system choices before the aircraft goes through a successive design freeze so that detailed structure and system design can work against a stable aircraft definition and experience a minimum of changes.
Virtually all systems in the aircraft and many structural parts are subcontracted from suppliers, and it’s important for all parties to have a design that doesn’t change once the detailed work packages are contracted to the supply chain.
If the above “pre-developing” of large parts of the aircraft is done successfully, it can shorten the aircraft’s project time in phases downstream of Conceptual and Preliminary design. The Preliminary design phase is expanded both in scope and work packages in this version, so it will not be shorter than the classical version. But it will speed up the total project if done correctly.