Aircraft design: expanding Vision (part I)

Jack Lie CNC machining expert

Specialize in CNC Milling, CNC Turning, 3D Printing, Urethane Casting, and Sheet Metal Fabrication Services.

Let us discuss the flow of the modern aircraft design cycle and give an example of how to use the services of a prototype manufacturer for prototype testing.

Thought history category: industrial design prototype

Feature images of prototype manufacturers for the aviation industry

Release time: December 23, 2020,| Runsom Precision

Among the most difficult engineering majors in the world, aerospace and aviation engineering are among the best. Any engineer who has read this article may be acquainted with the normal design cycle referred to any product design, but so much challenging caused by the level of complexity requirement of aviation industry.

Modern aircraft design are facing with strict operational, environmental and financial challenges. In terms of how to design complex systems and how to avoid design flaws, people have noticed a huge paradigm shift, just like the latest Boeing 737 Max. In this paper,  the flow of the modern aircraft design cycle and examples of how large-scale testing using the services of a prototype manufacturer can save the situation will be carefully discussed.

Explore more details about industrial design prototypes here.

 The design cycle of modern aircraft

Every designer who reads this paper may be acquainted with the three basic design stages: conceptual design, preliminary design and detailed design. However, fierce competition among market participants and high customer expectations mean that companies must make significant innovations in the design phase to meet different standards. Let us use the chart below to discuss the aircraft design cycle based on life cycle cost.

As you know, the first three stages before the manufacturing stage account for 95% of the total cost. During the first three stages, the first stage is more important than the other two, namely planning and conceptual design. So let us concentrate on the details of first stage, and then the other two stages.

Planning and conceptual design

First of all, feasibility study will be conducted to make sure if the existing technology can meet this requirement. In addition, the path of the project can be optimized by the feasibility study, namely a complete redesign, which means the highest risk and cost, or the adoption/modification of an existing design. Next, the conceptual design phase begins. Any aircraft designer knows the Raymer and Roskam models very well. As they descriped, the conceptual design phase includes answering the following basic questions:

Will it be effective?

What does it seems to be?

What are the requests?

How to optimize the transaction?

How to optimize weight and cost?

To identify and prepare a feasible and optimal design concept for further refinement is the final goal of the conceptual design stage. Therefore, this stage includes the production, research and inspection of various design concepts, all of which require little knowledge of experimental results and limited data on the useful design. The chart below this paragraph describes the greater range of uncertainty in the concept phase which compared to the advanced phase. In addition, the life cycle cost incurred at this stage is as high as 65%, which means any subsequent changes to the basic design will mean a reduction in total revenue and an extension of the deadline.

The common obstacle in the conceptual design stage is that a set of requirements is not clearly listed when the design process is started. It is very important to outline market needs and let customers know their expectations clearly. Uneconomical and inefficient methods is refining requirements at a later stage, and such a design cycle can seriously affect the life cycle costs generated. As far as aircraft design is concerned, customer requirements and expectations often conflict with each other. Based on the different components of the aircraft, such as wings, engines, fuselage, landing gear, tail and canards, etc., a diverse and complex aircraft system means multiple challenges.

Its an art in dealing with this problem itself, which is why techniques such as multiple attribute decision making (MADM) are used to facilitate this type of decision making. With the help of these techniques, implied considerations start to play a role and move from single-point deterministic methods of decision making to dynamic and parametric methods. In addition, techniques such as multidisciplinary analysis and design optimization are essential to satisfy the complex set of constraints in this environment. The diagram below outlines this technique, which describes the interaction between different aviation disciplines.

In view of the aforementioned uncertainty in the conceptual design stage, the established method is based on probability theory and design methods. These methods included in the usage of probability density functions (PDFs) and cumulative distribution functions (CDFs) for each design constraint. Then draw and analyze the data of several design constraints. These accumulated data allow the designer to clearly understand the design area and whether he or she needs to relax any restrictions or introduce any technology to improve the design cycle as a whole.

In a word, the designer has established a relationship between input and output variables while considering the variability of input factors.

Initial design

This stage is highly critical to the size of the various design factors of the concept completed in the first stage. This requires in-depth research and analysis of the interdisciplinary interactions among aircraft systems and subsystems. For example, a combination of structural mechanics and aerodynamics is the concept of aeroelasticity.

In today’s modern engineering era, the considerations such as reliability, maintainability, stability, control, safety, and economy is included in the preliminary design stage. Now, more detail aout the challenges faced in this design phase and the best way to deal with them will be discussed here.

Precise, complex and precise modeling requires the use of advanced numerical algorithms, such as computational fluid dynamics and finite element analysis. However, the unusually high computational cost means another challenge for designers. The figure below graphically illustrates the trade-offs involved in choosing high-fidelity tools and using simple simulations.

The development of complex and high-fidelity tools not only means higher computational costs, but also challenges in dealing with multiple variables (usually up to hundreds) and their interdependence. Therefore, a lot of time is spent on identifying and mapping the simulation environment. (The story is not over!!)

If you want to know more, please continue to read “Aircraft Design (Part 2): Expanding your horizons“. thank you!