In the following text, technological development is understood to be the development of hardware with a focus on materials and finishing methods.
Despite the high costs and risks, technological development is necessary to ensure future viability. In engine construction, this is primarily (in terms of expense) done evolutionarily within the framework of series development. The development of a new engine type demands such extensive resources, that even large OEMs search out partners for various components and modules.
New technologies involving revolutionary steps are found almost exclusively within the framework of military development. Government involvement makes the financial risks bearable. Design and testing for military applications is typically long-term and the desired operating times (2000 h) are relatively overseeable relative to those of civilian applications (20,000 h). Following successful military testing, use in civilian applications usually has tolerable risks. It must be noted that material-technological developments occur in stages of several 5-years. Within and between these stages, the state of development and the chances of realization (gate) should be checked. The path from the initial concept to rather unlikely serial implementation can be expected to take 15-20 years. The first of these developments stages is best done in universities and institutes under the observation of the potential industrial user. Only after technologies have proven themselves in military applications can the transition be made to civilian applications. Examples for this procedure include single-crystal materials, thermal barrier layers, and cooling technologies. What is the incentive for a capital investment as risky as technological development? It is the customer`s desire for a product that improves his position in the market. Factors that aid in this are primarily low energy consumption and low operating costs. In military applications, there are also special mission requirements and the highest possible thrust/weight ratio. The advantages for potential customers justify corresponding development expenses if it can be assumed that they will be realized in later sales income. The potential of the technologies must naturally be seen in connection with the future core business and the planned product portfolio. For material technologies in engine design, the strength change over temperature is an important criterion (Fig. "Potential of new material technologies").
Chapter 14.1 gives a more exact overview of the development process. This includes setting goals and typical procedures.
The selection of an optimal process depends on many requirements and limiting factors. These include:
Experience has shown that decision makers should bring in certain requirements in order to increase the probability of success of a development. For example, one should not merely copy competitors` technologies to reduce costs and time investments. This would create a high risk of unexpected problems occurring. It is very difficult to recognize and take into account all important details of a design without understanding its function in sufficient detail (Fig. "Seen does not mean understood").
Apparent improvements, usually simplifications, can reveal themselves as unallowable after it is already too late. It can be assumed that the competitors have already considered the “simple” solutions and discarded them (Fig. "Mistakes at project start"). Such “dead ends” can usually be avoided by continuous, sufficiently long-term own development work.
Chapter 14.2 attempts to more clearly explain risks and problems of technological development.
Chapter 14.3 provides information regarding procedures that minimize the development risk.
Figure "Mistakes at project start": Experience has shown that the development direction or technology that seems simplest initially does not always lead to the desired success. It is frequently attempted to replace constructively solvable expenses with material technology. Only later is it revealed that it cannot be realized even with ones own effort. For example, in a single-piece turbine stator made from monolithic ceramic (bottom right diagram), the assembly and finishing of many individual parts is avoided, but the thermal fatigue behavior, force transfer from the carrying structure, and the guarantee of the necessary strength properties are very problematic.
A hybrid version (bottom left diagram) avoids these problems but is a more expensive design.
Figure "Seen does not mean understood": Only designs that one has developed oneself and inspected in sufficiently realistic tests can be seen as being sufficiently well understood. This is the prerequisite for acceptably safely estimating risks of development to serial implementation.
The bottom left diagram shows inconspicuous design characteristics that ensure acceptable containment behavior of a housing (see Volume 2, Ill. 8.2-15).
The right diagram shows a containment ring made from aramdid fibers. Its unique shape, with a ring-shaped space filled with honeycomb material transitioning to a thin, conically shaped inner wall, are important characteristics of its function (see Volume 2, Ill. 8.2-14).