Mikhail Goman

State-space representation of aerodynamic characteristics of an aircraft at high angles of attack

Mathematical modeling of unsteady aerodynamic forces and moments plays an important role in aircraft dynamics investigation and stability analysis at high angles of attack. In this article the state-space representation of aerodynamic forces and moments for unsteady aircraft motion is proposed. Consideration of separated flow about an airfoil and flow with vortex breakdown about a slender delta wing gives the base for mathematical modeling using internal variables describing the flow state. Coordinates of separation points or vortex breakdown can be taken, e.g., as internal state-space variables. These variables are governed by some differential equations. Within the framework of the proposed mathematical model it is possible to achieve good agreement with different experimental data obtained in water and wind tunnels. These high angle-of-attack experimental results demonstrate considerable dependence of aerodynamic loads on motion time history.

Application of bifurcation methods to nonlinear flight dynamics problems

Abstract Applications of global stability and bifurcational analysis methods are presented for different nonlinear flight dynamics problems, such as roll-coupling, stall, spin, etc. Based on the results for different real aircraft, F-4, F-14, F-15, High Incidence Research Model, (HIRM), the general methods developed by many authors are presented. The outline of basic concepts and methods from dynamcal system theory are also introduced.

Evaluation of Aircraft Performance and Maneuverability by Computation of Attainable Equilibrium Sets

An aircrafts performance and maneuvering capabilities in steady flight conditions are usually analyzed considering the steady states of the rigid-body equations of motion. A systematic way of computation of the set of all attainable steady states for a general class of helical trajectories is presented. The proposed reconstruction of attainable equilibrium states and their local stability maps provides a comprehensive and consistent representation of the aircraft flight and maneuvering envelopes. The numerical procedure is outlined and computational examples of attainable equilibrium sets in the form of two-dimensional cross sections of steady-state maneuver parameters are presented for three different aircraft models.

Aircraft dynamics at high incidence flight with account of unsteady aerodynamic effects.

An invited paper with the results of collaboration between TsAGI, Russia and DMU, UK, funded by DERA/QinetiQ, Bedford UK. The phenomenological approach formulated to nonlinear unsteady aerodynamics modelling is adopted in DLR/Germany (R.V. Jategaonkar jategaonkar@dlr.de), ADA/India (Program Director T. G. Pai tgpai@iitk.ac.in ), presented in “Aircraft System Identification: Theory and Practice” by V.Klein and E.A.Morelli, AIAA Education Series, 2006, pp.484 (see p.59 and 72). The experimental technology for real-time unsteady loads measurements using hot-film sensors has been “...inspired by Goman and Khrabrov’s work…” (see NASA/TM-2004-212854, pp. 3-4, http://www.nasa.gov/centers/dryden/pdf/88785main_H-2568.pdf).

Computation of Controllability Regions for Unstable Aircraft Dynamics

This output describes an approach based on geometrical and optimisation principles that resulted in efficient software tools for computation of null controllability region of unstable dynamical systems. The software toolset, “Stabcalcs” has been created and tested on several flight dynamics applications and delivered to DERA/QinetiQ Ltd. within Computational Framework for flight clearance applications (in 2002-2003, DERA/QinetiQ Ltd Technical Manager Yoge Patel, yoge@bbsr.co.uk). The research was sponsored by QinetiQ Ltd.

SUPRA - Enhanced Upset Recovery Simulation

The SUPRA research project - Simulation of Upset Recovery in Aviation - has been funded by the European Union 7th Framework Program to enhance the flight simulation envelope for upset recovery simulation. Within the project an extended aerodynamic model, capturing the key aerodynamics during and beyond stall for a large category transport aircraft and new motion cueing solutions for both hexapod and centrifuge-based platforms were developed. This paper describes the recent piloted evaluation experiments. In the first experiment a group of ten experimental test pilots, with actual experience in stall conditions, subjectively judged the validity of the aerodynamic model and the motion cueing solutions in the simulators in different upset conditions. Pilots rated the stall behavior of the SUPRA model as representative and useful for training. They preferred improved over conventional hexapod motion cueing. Centrifuge-based cuing was considered highly valuable to recognize the positive G-loads during the late recovery phase. The second experiment showed that line pilots without previous exposure to upset conditions perform more conservative recoveries under actual G-loads in the centrifuge compared to hexapod. After some practice the number of stick shaker events and excursions into critical angle-of-attack was reduced. We conclude that the SUPRA aerodynamic model successfully demonstrates upset conditions, including stall, and that conventional hexapod motion cueing can be improved for the purpose of upset simulation. If available, centrifuge-based simulation of the G-load is a recommended addition to the upset recovery training.

Multi-Degree-of-Freedom Wind-Tunnel Maneuver Rig for Dynamic Simulation and Aerodynamic Model Identification

A new five-degree-of-freedom rig for the dynamic wind-tunnel testing of aircraft models has been developed. The maneuver rig enables a large set of conventional and more-extreme aircraft maneuvers to be performed in the controlled environment of a wind tunnel, allowing direct physical simulation of in-flight maneuvers and the identification of aerodynamic models from aircraft-model time histories. A mathematical model of the rig has been developed for numerical simulation and identification purposes. The development of a quasi-steady aerodynamic model of the longitudinal motion for a subscale test aircraft is presented to illustrate rig capabilities. The longitudinal modes of motion are excited by a remotely controlled aircraft-model stabilator and dynamic-rig aerodynamic compensator deflections. Two rig configurations are considered: aircraft-model pitch only and aircraft-model pitch with heave, which is implemented via rig-pitch motion. The aircraft-model tail and wing in the mathematical model are cons...

Developing Scenarios for Research into Upset Recovery Simulation

This paper gives an overview of the European Framework Programme 7 project SUPRA – Simulation of Upset Recovery in Aviation, a European research effort involving nine partnering organizations from the Netherlands, Austria, Spain, Russia, the United Kingdom and Germany aiming at developing new concepts of ground-based upset recovery simulation for use on hexapod-type as well as centrifuge-based simulators. Along with a general overview of the project objectives the paper reports on the status of the R&D effort including some of the first important decisions taken within the project such as the definition of a set of upset scenarios to be used by SUPRA for benchmarking of the concepts developed by the project.

Global Stability Analysis of Nonlinear Aircraft Dynamics

Global stability analysis of dynamical system implies determination of all the systems attractors and their regions of asymptotic stability. Numerical methods necessary for global stability analysis are outlined: SSNE algorithm for systematic search of all the solutions of nonlinear system of equations, and two algorithms for computing cross-sections of asymptotic stability region boundaries. Results obtained during investigation of aircraft roll-coupling problem are presented as an example of global stability analysis.

Analysis of Aircraft Nonlinear Dynamics Using Non-Gradient Based Numerical Methods and Attainable Equilibrium Sets

Multiple equilibrium solutions of aircraft motion equation are investigated using nongradient based numerical methods and computation of attainable equilibrium sets. The proposed approach may be applied to realistic industrial scale aircraft aerodynamic models based on look-up data tables. Advantages of this method and its joint use with predictorcorrector techniques for continuation and bifurcation analysis of aircraft nonlinear dynamics are discussed. A number of computational examples for aircraft dynamics investigation are presented for a generic airliner aerodynamic model developed within the SUPRA research project – “Simulation of Upset Recovery in Aviation” – funded by the European Union 7 th Framework Program.