A predominant problem in the US as well as in Europe is the imminent capacity shortage of major hub airports: Air traffic is assumed to increase significantly worldwide, while further runway extensions of airports are difficult because of residents’ resistance and limited land space availability. However, the increasing market size also provides a potential for new aircraft concepts. What type of aircraft will meet best the future market requirements is a question arising.

We show that currently discussed solutions to airport capacity problems are mostly not in line with market requirements and have therefore not the potential to alleviate the increasing capacity problems. We analyse to what extend an aeroplane with extreme short takeoff and landing (ESTOL) capability might be able to overcome these capacity problems and discuss resulting technical requirements. Subsequently we present some of the current technological challenges in this area of research and give an overview on ESTOL regional jet concepts that are currently investigated at Bauhaus Luftfahrt.

The use of flow control (FC) technology on civil transport aircraft is seen as a potential means of providing a step change in aerodynamic performance in the 2020 time frame. There has been extensive research into the flow physics associated with FC. This paper focuses on developing an understanding of the costs and design drivers associated with the systems needed and certification. The research method adopted is based on three research strands:

1. Study of the historical development of other disruptive technologies for civil transport aircraft,

2. Analysis of the impact of legal and commercial requirements, and

3. Technological foresight based on technology trends for aircraft currently under development.

Fly by wire and composite materials are identified as two historical examples of successful implementation of disruptive new technology. Both took decades to develop, and were initially developed for military markets. The most widely studied technology similar to FC is identified as laminar flow control. Despite more than six decades of research and arguably successful operational demonstration in the 1990s this has not been successfully transitioned to commercial products. Significant future challenges are identified in cost effective provision of the additional systems required for environmental protection and in service monitoring of FC systems particularly where multiple distributed actuators are envisaged. FC generated noise is also seen as a significant challenge. Additional complexity introduced by FC systems must also be balanced by the commercial imperative of dispatch reliability, which may impose more stringent constraints than legal (certification) requirements. It is proposed that a key driver for future successful application of FC is the likely availability of significant electrical power generation on 787 aircraft forwards. This increases the competitiveness of electrically driven FC systems compared with those using engine bleed air. At the current rate of progress it is unlikely FC will make a contribution to the next generation of single-aisle aircraft due to enter service in 2015. In the longer term, there needs to be significant movement across a broad range of systems technologies before the aerodynamic benefits of FC can be exploited.

Hutapea et al showed that an actuation system based on shape memory alloy coils could be employed for a wing flap of an aircraft. A continued research and development of these previously demonstrated smart flight control mechanisms was performed with the goal to develop a proof-of-concept shape memory alloy (SMA) actuation system, which utilises SMA springs to control the six degrees of freedom of an aircraft. For this actuation system, the springs are heated via an electric current, causing the spring to contract as the metal’s phase changes from martensite to austenite. The contraction allows the springs to function as linear actuators for the aircraft’s control surfaces, specifically the flaps and ailerons on the wings and horizontal stabilisers and a rudder on the tail. As a significant advancement to the overall actuation system, an air burst-cooling system increases the cooling rate of the coils by means of forced convection. Computer-based finite element model analysis and experimental testing were used to define and optimise SMA spring specifications for each individual control surface design. A onesixth scale proof-of-concept model of a Piper PA-28 Cherokee 160 aircraft was constructed to demonstrate and to verify the final actuation system design.

This paper presents a methodology for calculating the operability and performance of split-flow fans with inlet distortion. A one-dimensional stage-by-stage model has been developed to include parallel compressor theory. The model is capable of providing a detailed definition of the circumferential and radial flow fields. The low-pressure fan is divided to three radial divisions, near-hub, near-tip, and mid-span. The characteristics of each radial segment are calculated by using fan radial profiles. The stable and unstable operations of a split-flow fan, with and without inlet distortion, have been investigated in this study. For the clean inflow surge was triggered by the core compressor, whereas the fan spoiled sector was found to cause the compression system to surge for the distorted case.

The Silent Aircraft Initiative was a Cambridge-MIT Institute programme involving a large team of researchers from both the University of Cambridge and the Massachusetts Institute of Technology (MIT). The aim of the project was to produce a concept aircraft design that would be so quiet it would be imperceptible in the urban environments around airports.. This paper gives an overview of how all the sources of engine noise were carefully addressed within the Silent Aircraft design. Novel technologies, a new engine configuration, improved airframe integration, new operational procedures and advanced component design were all required in order to reduce the overall engine noise level to the Silent Aircraft target. The study suggests that in order to dramatically reduce the noise of future aircraft engines a number of major design changes must be combined.

This paper investigates the performance of a flight control system, based on nonlinear dynamics inversion theory, whose aim is to maintain a given geometry of a formation of unmanned aerial vehicles. A fundamental aspect is the complete three dimensionality of the formation geometry that provides a substantial improvement over existing two-dimensional control laws. The designed control system has been implemented in a Simulink® environment and its effectiveness has been tested with a campaign of numerical simulations.