Conventional Transport Aircraft Research Articles

Static loads evaluation in a flexible aircraft using high-fidelity fluid–structure iteration tool (E2-FSI): extended version

This paper presents a fluid–structure iteration method applied as a study case to a conventional transport aircraft with wing aspect ratio of 12. It evaluates the nonlinear structure effect on the calculation of static limit loads. The numerical tool presented herein is named E2-FSI, which stands for nonlinear high-fidelity static fluid–structure iteration, developed for high flexibility static aeroelastic evaluations. A discussion about the use and the applicability of high-fidelity static fluid–structure iteration for the calculation of static loads is presented as part of the conclusion, for both current and future conventional transport aircraft.

Boundary-layer transition of advanced fighter wings at high-speed cruise conditions

The achievement of laminar flow in the boundary layer at high-speed cruise conditions may further, in addition to shock-wave control, reduce the drag and extend the range of military fighter aircraft. To this end, a further investigation on transitional boundary-layer flow of fighter wings is needed due to different configurations from the wings used on conventional transport aircraft. In this paper, wind tunnel experiments and numerical simulations were conducted on three-dimensional transition of thin diamond-shaped wings used on advanced fighter aircraft at tran/supersonic design points. A newly proposed correlation of crossflow transition which includes the effect of surface roughness was introduced into the γ-Reθt transition model. Predicted results were in good agreement with flow visualizations. Results showed that the strength of the crossflow component grew rapidly around the leading edge because of the severe flow acceleration, just as the same as wings with a large aspect ratio. However, there seemed no regular pattern of instability-dominance variation in span-wise for a diamond configuration. The dominance of different instability mechanisms strongly depended on the local pressure distribution. Hereby, the research recommended a “roof-like” shape of pressure distribution to suppress both crossflow and Tollmien-Schlichting (T-S) instabilities. Besides, a sharp suction peak with a serious pressure rise should be cut off to avoid stronger instabilities. Further discussions also revealed an independence of the unit Reynolds number when transition was triggered by T-S instabilities. Aerodynamic force comparisons indicated that further benefit on drag reduction could be expected by including the three-dimensional transition effect into a wing design process.

Crashworthiness and ditching behaviour of blended-wing-body (BWB) aircraft design

Over the last few decades, the fuel efficiency of aircrafts was mainly improved by the application of refined aerodynamics, new materials, structural optimization and enhanced engine performance. A further potential for a greener aircraft is seen in the unconventional blended-wing-body (BWB) design configuration due to its advanced aerodynamic design and its reduced weight. For the certification of novel aircraft configurations, the airworthiness authorities require proof of at least equivalent safety standards compared to the existing conventional transport aircraft. In this context, the BWB configuration has to demonstrate sufficient crashworthiness for emergency landing on rigid surface and on water. Since structural modifications for improved safety should be applied in the early conceptual design phase of an aircraft, explicit simulations have been performed with the objective to estimate the crash behaviour of the BWB configuration. Based on the simulation results, design principles are derived for improved crashworthiness and ditching behaviour for the BWB aircraft configuration.

Four-dimensional guidance of atmospheric vehicles

The nonlinear control theories based upon the model predictive control and the nonlinear inverse control are used to develop four-dimensional guidance controllers, the conversion of the primary trajectory being assumed by a specific solution to the inverse kinematics problem. The control task is simplified by using the forced singular perturbation theory, overall system dynamics being separated into the fast and slow reduced-order systems and separately controlled. The algorithm performances are evaluated in the case of a conventional transport aircraft that tracks a four-dimensional trajectory defined by flight levels, waypoints, and an estimated time of arrival. The predictive control and dynamic inversion are compared as basic algorithms for the fast-dynamics control in view of establishing performances and limits.

The Noise of Rotorcraft and other VTOL Aircraft— A Review

The need to understand the mechanism of generation and to be able to predict the noise of aircraft has increased enormously in the present decade. The questions which the aircraft designer now poses to the noise engineer are much more difficult to answer than was the case in 1964 when rotorcraft noise was discussed by this Section. For example in the case of conventional transport aircraft at the beginning of this decade it was only necessary to show that on take off the peak noise did not exceed 110 PNdB at a predetermined monitoring point at certain airfields. With the advent of noise certification it is now necessary to know the complete noise time history of the aircraft for points under the take off path, at the side and on the approach before the aircraft flies or the engine is made. The increased emphasis on noise research and the resulting developments in the theory and practice is not surprising.

STOL Aircraft—A Perspective

SummaryThe interest in Canada in the design and manufacture of utility aircraft with a short take-off and landing (STOL) performance may be traced back to the difficulties of surface transport in the early development of the country and the widespread use of bush aircraft.The leading characteristics of the STOL aircraft are examined with particular reference to design features essential to a short take-off and landing. The choice of powerplants and lifting systems is discussed with emphasis on the requirements for powered lift in the larger sizes of aircraft. The augmentor-wing is described as an example of an integrated propulsion lifting system with promise of a high performance.The phases of the take-off, transition, climb and landing manoeuvre are reviewed to illustrate the relative importance of various parameters in design and operation. The importance is stressed of good stability characteristics and effective controls for manoeuvring in a confined air space and a consistent landing performance.The requirements of a para-military mobile force tor a rapid response, deployment overseas and transportation in an area are examined. Some estimates are given of the probability of finding suitable airstrips in a particular region and the cost of constructing new airfields in a dynamic situation. The operating environment in potentially troubled areas of the world is examined briefly to provide guidance in design. The costs of a military supply system are discussed using various modes of transport which include trucks, helicopters, STOL and conventional transport aircraft with results which suggest that the system employing STOL aircraft in the tactical theatre has advantages in cost and effectiveness.Attention is drawn to the growing requirement for shorthaul, commuter and air taxi aircraft with STOL characteristics. Reference is made to the increases in air travel and the widespread use of large transport aircraft which have encouraged the movement of airports from urban centres at a time when city growth and congestion render surface transport increasingly difficult. The relative costs of commercial systems using the helicopter and STOL aircraft are examined. It is shown that the cost of STOL ports is not an excessive portion of total system costs when all factors are taken into account. Some forecasts are made as to future development trends in transport systems using STOL aircraft.