Long-range Transport Aircraft Research Articles

Potential Estimation of Load Alleviation and Future Technologies in Reducing Aircraft Structural Mass

In recent years, load alleviation technologies have been more widely used in transport aircraft. For aircraft already in service, load alleviation can contribute in extending the fatigue life, or enable small configurational changes. If load alleviation is considered in the aircraft design process, the structural mass of the aircraft can be reduced. This paper investigates various maneuver and gust load alleviation algorithms as well as potential future technologies regarding flight operation, turbulence forecast and material science, and it evaluates the mass reduction that can be achieved. In doing so, a long-range transport aircraft was taken as the reference, and the considered load case conditions were 1-cos gusts, maneuvers and quasi-steady landing. Based upon the loads, the composite structure of the lifting surfaces was optimized, while the secondary masses as well as the wing planform were kept unchanged. With all technologies implemented, a reduction of the wing box mass by 26.5% or 4.4% of the operating empty mass could be achieved.

Exergo-economic cost analysis for a long-range transport aircraft propulsion system at non-linear power loads

The several series of PW4000 high bypass turbofan engine have used so far in many aircrafts. These commercial engines are closely related to environmental impacts and security of energy supply. In this study, exergo-economic analysis which is useful tool to investigate existing potential for cost-effective components was carried out. Therefore, exergo-economic indicators of PW4000 engine was examined by employing energetic, exergetic and economic relations at non-linear different power settings. Moreover, exergo-economic performance of PW4000 and its components was explored with several parameters such as exergy destruction cost ($/h), exergo-economic factor (%) and specific thrust cost ($/hkN). Based on the results of exergo-economic analysis, a specific cost of Fan thrust was found about 3 times lower than Exhaust thrust at maximum revolution per minute (RPM). Namely, specific thrust costs of Fan and Exhaust were estimated 14.47 $/hkN and 54.78 $/hkN respectively. Considering the lowest and highest power settings, exergo-economic factor of the PW4000 engine was found as 17.28% and 10.59%, respectively. On component basis, the highest exergo-economic factor, ranging from 57.42% to 86.32%, was observed at Low Pressure Compressor (LPC) unit. Finally, exergy destruction cost, varying from 655 $/h to 1688 $/h, was found the highest at Combustor throughout RPM values. This study can help in understanding the nature of the relationship between non-linear power settings and the relevant exergo-economic parameters.

Cost-range trade-off of intermediate stop operations of long-range transport airplanes

The objective of this study is to show the environmental and operating cost savings that could be achieved if long-range transport aircraft were designed for shorter ranges, and long-range flights were operated with an intermediate stop, obviously, with the drawback of longer trip duration and the increase in the number of flight cycles. The maximum take-off weight and operating empty weight, the main design variables of transport airplanes, noticeably diminish. The overall result depends on the length of the route, the extra distance due to the detour, the location of the intermediate airport and the technology level (range factor and operating empty weight fraction with respect to the maximum take-off weight). In all the routes analysed, the uneven splitting between both legs plays a secondary role. It is shown that long routes are well adapted to intermediate stop operations, particularly when the airliner serving the route has been designed for a medium range. However, intermediate stop operations produce a negative impact for medium and short city pair distances, since the reduction in aircraft weight is more than counterbalanced by the extra fuel and time required in the non-cruise phases of the flights.

An all-composite, all-electric, morphing trailing edge device for flight control on a blended-wing-body airliner

For a significant improvement in the fuel efficiency of long-range transport aircraft, a transition to blended-wing-body (BWB) configurations will be required in the long term. Further efficiency improvements are expected from an all-composite primary structure, all-electric actuation, as well as from seamless control surfaces that provide reduced drag compared to conventional control surfaces. BWB configurations feature specific demands on the control system because of the high coupling between flap deflections and aircraft movements in all three axes. Thus, multi-objective control surfaces are required for flight control, as well as for active gust and manoeuvre load alleviation. A major challenge therefore is to provide sufficient yaw control and stability in the absence of a vertical tail. Generally, one engine inoperative poses an important sizing case for the control system design, especially for the control surfaces. In this article, the sizing of winglet flaps and crocodile flaps is performed for the preliminary design of an all-composite, all-electric BWB airliner. For further improvement in efficiency, a seamless morphing trailing edge device is designed that provides both crocodile flap and aileron modes at the same time. Based on these results, a composite morphing trailing edge demonstrator with an all-electric actuation system is investigated. Some open issues remain for investigation. Still, the proposed design provides a promising approach for further efficiency improvement on BWB aircraft configurations.

The En-route to Terminal Area Interface

Long-range transport aircraft of the next decade will almost certainly contain a navigation system capable of providing accurate and reliable fixing and flight director information over any part of the world. Over the North Atlantic Ocean die navigation system must be reliable enough to ensure safety at an agreed separation between aircraft flying in a controlled environment. At the conclusion of the en-route part of a flight these long-range aircraft pass through an interface of some 200 or 300 n.m. radius around the terminal airfield before they come within the close terminal control, with its specialized aids to approach, landing, take-off guidance and holding. The interface is currently served by a variety of radio and radar aids, all ground based at the present time. Aircraft are monitored by primary radar on the ground while they fly along airways some 10 n.m. wide with the aid of VOR/DME, Decca/Harco or A.D.F. The aids used depend upon the traffic density experienced in the area, the geographical environment and many other factors. At this time when consideration must be given to the development of an accepted navigation system for the interface, it is important that close attention should be given to the employment wherever possible of a rational navigation system compatible with all en-route systems and terminal area aids. The system used in the interface should use as much of die en-route and terminal equipment as possible, perhaps eventually removing the airways interface, as we know it, altogedier. Several techniques should be considered, diey include die use of ground radar for die precise up-dating of doppler and inertia navigation aids, die use of differential Omega for up-dating widi conventional Omega and ground radar for gross-error monitoring, and die use of ILS localizer beams used in conjunction with a downwind localizer aerial for the provision of a service presendy supplied by VOR and ADF.