Review of Flight Dynamics

F LIGHT dynamics education has historically been dominated in the classic textbooks by Etkin and Reid [1], McRuer et al. [2], Roskam [3], McCormick [4], and Nelson [5]. All of these texts are largely based upon the seminal textbook from the 1940s by Perkins and Hage [6], and the linear modeling methods contained in the U.S. Air Force Data Compendium (DATCOM) [7]. Because Perkins and Hage [6] and Hoak and Finck [7] use the component buildup approach of dividing the aircraft into wing, wing–body, and wing–body–empennage elements, these methods were satisfactory for most military and civil designs up through the 1960s. With the introduction of aircraft with significant wing–body blending in the 1970s (B-1, F-16, F/A-18), and highly unconventional configurations in the 1980s (YF-23, F117) and 1990s (X-45), the methods presented by these historical textbooks were clearly becoming less relevant. These newer configurations can possess significantly different features which have a pronounced effect on stability and control, such as chined forebodies, serrated trailing edges, and unusual fuselage cross sections. Although aircraft such as the SR-71 possessed some of these features as far back as 40 years ago, the point is that these features are almost commonplace today. Numerical methods of all kinds have made tremendous strides in the intervening years too. In addition to the wellpublicized advances in computational fluid dynamics (CFD), the area of fluid/structure interaction, and in particular aeroelasticity, has experienced significant advances. An improving capability to analyze highly nonlinear aeroelastic problems, such as the decades-old problem of wing store flutter in high-performance fighter aircraft, is opening a door previously shut to undergraduateand graduate-level flight dynamics, stability, and control courses [8]. Since 2000, there has been a resurgence in flight dynamics textbooks, as witnessed by the introduction of modern texts such as Pamadi [9], Yechout et al. [10], Schmidt [11], and Phillips [12]. The subject of this review is the latest newcomer to this group, and at 845 pages of text is essentially the tome of career works of distinguished researcher and educator, Robert F. Stengel. Many items from his previous text [13] and his scholarly publications have been masterfully integrated throughout this text. It should be noted up front that this text is unique and represents a significant departure from both the classic texts and its modern text peers. The first significant difference is in scope and intended audience. The overview is a broad background in both engineering and engineering science, and the intended audience is not only undergraduate students, graduate students, practicing engineers, and researchers, but also interested nonaeronautical engineers and aircraft enthusiasts in general. For this reason, the text covers subjects as elementary as trigonometry, right up through linear algebra. To quote the text, “The book is intended for readers with a broad background and interest in engineering and science. . .Because it uses common notation and does not assume a strong background in aeronautics, Flight Dynamics is accessible to a wide variety of readers.” The presentation in Flight Dynamics is also unique. It uses a very novel approach to integrating and developing its topics and methods, instead of using the traditional Perkins and Hage [6] incremental development style. In pedagogical terms, Flight Dynamics uses a problembased learning (PBL) approach vs the traditional topicalbased learning. This means that each major section starts with the posing of a problem, and then introduces the mathematics and analysis methods on an as-needed basis, right in the chapter, instead of placing them in stand-alone chapters or appendices. For example, eigenvalues, eigenvectors, and positive definite matrices are introduced on page 173 during the development and discussion on principal axes, as is matrix modal modeling. Classical and modern linear system methods such as Bode, root locus, and Nyquist plots are also interwoven throughout the text, instead of appearing in their own chapters or appendices. Interestingly, both time-domain and frequency-domain techniques appear almost interchangeably in the same sections of the text. This fresh approach will be sure to have its adherents, but possibly also its detractors, who will want to see topics such as numerical integration algorithms, linear algebra, and Fourier and Laplace transforms appear in appendices or dedicated chapters, not tightly woven throughout the text. JOURNAL OF GUIDANCE, CONTROL, AND DYNAMICS Vol. 30, No. 6, November–December 2007