The design of the landing gear is one of the more fundamental aspects of aircraft design. The design and integration process encompasses numerous engineering disciplines, e.g., structure, weights, runway design, and economics, and has become extremely sophisticated in the last few decades. Although the design process is well-documented, no attempt has been made until now in the development of a design methodology that can be used within an automated environment. As a result, the process remains to be a key responsibility for the configuration designer and is largely experience-based and graphically-oriented. However, as industry and government try to incorporate multidisciplinary design optimization (MDO) methods in the conceptual design phase, the need for a more systematic procedure has become apparent. The development of an MDO-capable design methodology as described in this work is focused on providing the conceptual designer with tools to help automate the disciplinary analyses, i.e., geometry, kinematics, flotation, and weight. Documented design procedures and analyses were examined to determine their applicability, and to ensure compliance with current practices and regulations. Using the latest information as obtained from industry during initial industry survey, the analyses were in terms modified and expanded to accommodate the design criteria associated with the advanced large subsonic transports. Algorithms were then developed based on the updated analysis procedures to be incorporated into existing MDO codes.

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Landing Gear Integration in Aircraft Conceptual Design

Lifting rotor blades flapping response to atmospheric turbulence, discussing time averaging and perturbation schemes

Flapping response of lifting rotor blades to atmospheric turbulence

The statistical discrete gust (SDG)-power spectral density overlap of y = 10.4A claimed by J. G. Jones, and verified by B. Perry III, A. S. Pototzky, and J. A. Woods, does exist. The analytical results consist of numerical substantiation of specific aircraft models. The claim is valid up to approximately ±10% about the 10.4 factor. This article presents a mathematically rigorous proof from basic principles without specific aircraft models and very restricted gust shapes. By invoking Chebyshev's inequality, the extension to ymax = 25-150A for true design gust loads becomes a reality to complete the holistic proof. This article also introduces the allencompassing fractal geometry representation of turbulence that uses their respective Hausdorff (fractal) dimensions to derive all known spectral shapes. A sample case explains the obvious impacts from these different shapes on gust load exceedance. A two-tier approach proposes concrete changes in FAR 25 requirements. Realistic assessment of SDG method's role in gust load analysis points out some of its shortcomings and virtues.

Statistical discrete gust-power spectral density methods overlap-holistic proof and beyond

This study raises some issues for training pilots to fly forced landings and examines the impact that these issues may have on the design of simulators for such training. It focuses on flight trajectories that a pilot of a single-engine general aviation a

Application of genetic algorithm to a forced landing manoeuvre on transfer of training analysis

A method for evaluating the structural compatibility of an aircraft (2) for use on a runway (5) having a profile with one or more roughnesses (7, 8) in the form of bumps and/or dips, comprising the steps of: generating (102) a first equivalent bump height curve (25) indicative of the elevation and/or depression of the one of more roughnesses of the runway with respect to a reference value; comparing (106) the first equivalent bump height curve with a second equivalent bump height curve indicative of elevation and/or depression limit values of reference roughnesses such that, when the aircraft encounters said reference roughnesses, it remains within the envelope of admissible loads; generating (103) a first power spectral density curve by means of spectral analysis of the profile of the runway; comparing (107) the first power spectral density curve with a second power spectral density curve (60) relating to a profile of a reference runway such that, when the aircraft runs along this reference runway, it remains within the envelope of admissible loads; verifying (108) if the first equivalent bump height curve (25) develops entirely within the first acceptability region and if the first power spectral density curve develops entirely within the second acceptability region; and authorizing or denying (112, 114, 116) the aircraft the use of the runway, on the basis of the result of said step of verifying (108).

John M. Firebaugh

Papers

Evaluations of a spectral gust model using VGH and V-G flight data.

Estimation of taxi load exceedances using power spectral methods.