8. Applicability of the aerodynamic coefficient models

Table 1 has given already some advises for possible application of the different models of the aerodynamic coefficients. The developed and advanced models open new fields of application including the investigation of the fully nonlinear situations including the aircraft chaotic motions and provide more accurate derivatives for maintaining stability and control.

The model application is based on the known technology identification, evaluation, and selection methodology [90, 91]. This methodology can be adapted to the aerodynamic coefficient model selection by using the following major steps:

1. Definition of the object, objectives, and goals

Define the object as thrust vectored aircraft, wing flutter, and objectives like managing the thrust vectored aircraft poststall motion, or reducing the amplitudes of the wing oscillation motion. Derive the goals from the objectives as investigation, design the new system, and control or manage with the object, etc.

2. Identification of the applicable models

Derive the preliminary specification of the required models for the definition of the object, objectives, and goals. Namely, the models might be local (used locally to a part of the aircraft or to well-defined motion regime, like cruise flight, only) or global (applying to the whole aircraft, or to the large part of flight envelope). Estimate which nonlinearities, delay, and hysteresis in aerodynamic coefficient may appear that should be taken into account.

Identify the possible models from literature review, preliminary investigations, brainstorming, etc.

3. Evaluation of the identified models

Study the identified models: especially evaluate how they can be integrated into the existing or planned systems (compatibility), how their changes or modification may improve their applicability for supporting the objectives (apply the morphological matrix), how their deployments have impact on the applying systems (impact matrix effect on the solutions like using the different control philosophy and control technique), how effective, safe, sustainable, etc. is their application, and how they might have influence on their selection (decision matrix).

The evaluation must be dealt with development of the final systems, including the production, supply chain, market introduction, etc.

The candidate models might be tested in simulation, or even in laboratory or flight tests. The tests must cover the full range of possible flight regimes and situations, and the result must be evaluated against the predefined indicators. The sensitivity analysis may detect the most important parts or elements of the models.

4. Selection of the best models for the aerodynamic coefficients required for reaching the predefined objectives

The selected models must be as simple as possible, while their application is (life cycle) cost-effective and they must support the objectives.

5. Development of the systems applying the selected aerodynamic coefficient models

The system developments include the hardware and software developments and a study of the total impact (effect on the life cycle cost, safety, security, and environment as chemical emissions and noise) and verification and validation of the created systems.

6. Final decision and deployment

Two specific aspects must be underlined: (i) the computational fluid dynamics may easily determine the aerodynamic coefficients by integration of the calculated surface pressure distribution and (ii) all the aerodynamic coefficient models described earlier can be applied, while better using the models as simple as possible depending on the goal and object of their

Table 1 has given already some advises for possible application of the different models of the aerodynamic coefficients. The developed and advanced models open new fields of application including the investigation of the fully nonlinear situations including the aircraft chaotic

The model application is based on the known technology identification, evaluation, and selection methodology [90, 91]. This methodology can be adapted to the aerodynamic coeffi-

Define the object as thrust vectored aircraft, wing flutter, and objectives like managing the thrust vectored aircraft poststall motion, or reducing the amplitudes of the wing oscillation motion. Derive the goals from the objectives as investigation, design the new system,

Derive the preliminary specification of the required models for the definition of the object, objectives, and goals. Namely, the models might be local (used locally to a part of the aircraft or to well-defined motion regime, like cruise flight, only) or global (applying to the whole aircraft, or to the large part of flight envelope). Estimate which nonlinearities, delay, and hysteresis in aerodynamic coefficient may appear that should be taken into account. Identify the possible models from literature review, preliminary investigations, brain-

Study the identified models: especially evaluate how they can be integrated into the existing or planned systems (compatibility), how their changes or modification may improve their applicability for supporting the objectives (apply the morphological matrix), how their deployments have impact on the applying systems (impact matrix effect on the solutions like using the different control philosophy and control technique), how effective, safe, sustainable, etc. is their application, and how they might have influ-

The evaluation must be dealt with development of the final systems, including the pro-

motions and provide more accurate derivatives for maintaining stability and control.

8. Applicability of the aerodynamic coefficient models

cient model selection by using the following major steps:

1. Definition of the object, objectives, and goals

and control or manage with the object, etc.

2. Identification of the applicable models

3. Evaluation of the identified models

ence on their selection (decision matrix).

duction, supply chain, market introduction, etc.

storming, etc.

application.

178 Flight Physics - Models, Techniques and Technologies

Depending on the previous points, the identification, evaluation, and selection process might be finished or started from the beginning. Of course, with the changes in aircraft structures, new ways of operation, application of the new solutions, and new emerging technologies, the aerodynamic coefficient models always must be refined or even the identification, evaluation, and selection process must be repeated again and again followed by improving or developing new solutions and systems improving the aircraft aerodynamic shape, aerodynamic characteristics, performance, stability, disturbed motion, and controllability.

Table 2 gives some advises on how to use the different models of the aerodynamic coefficients.


Table 2. Some recommendations on the usage of the aerodynamic coefficient models.
