In general, an airship is equipped with hybrid-heterogeneous actuators: the aerodynamic surfaces, the vectored propellers and the buoyant ballonets. The aerodynamic surfaces have high efficiency in attitude control at high speed. However, vectored propellers are also introduced here for attitude control under the special working condition of low airspeed. Due to the lower thrust-to-weight ratio, the composite control of hybrid-heterogeneous actuators is the primary object in controller design for an airship. In composite attitude control, first the attitude moment allocation between aerodynamic control surfaces and vectored propellers is designed according to different dynamic airspeed, to achieve the smooth motion transition from low to high airspeed, then the weighted generalised inverse (WGI) is used to design the reconfigurable actuator allocation among the homogeneous multi-actuators, where the authority of every actuator can be decided by setting the corresponding value of the weight matrix, thus the control law is unchanged under different actuator configurations. Taking the mid-altitude airship as an example, the simulations of position control, trace tracking and altitude control are provided. Simulation results demonstrate that the attitude moments allocation obtains moment distribution between the aerodynamic surfaces and the vectored propellers under different airspeeds; the reconfigurable actuator allocation achieves a good distribution and reconfiguration among homogeneous actuators, thereby enhancing the reliability of the control system.

I am stepping down as Editor-in-Chief of The Aeronautical Journal at the end of May. This was not an easy decision to make, as I have very much enjoyed being involved with the Journal over a period of some 15 years but it was time for a younger person with fresh ideas and fresh energy to take over the reins. My association with the Journal began in the early 2000s when the Editor at the time, Professor John Stollery, invited me to take over the Chair of a small editorial group that had been set up by Eric Rogers of the National Physical Laboratory to oversee the production and development of the Journal. The Group, which continues to meet monthly, consisted at the time of the Editor, the Chairman and key members of the Publications Department. In May 2005, the Group was strengthened by the arrival of Professor Mike Graham. Unfortunately personal reasons forced John Stollery to retire from the Editorship in December 2006 and he asked if I would take over the position. I agreed and Mike Graham then became the Chairman of the Editorial Group. More recently, the Group, which is now entitled the Editorial Committee of The Aeronautical Journal, was strengthened further by the appointment of Professor Chris Atkin as Deputy Chairman.

Through an analysis of TAWS/FMS data collected and registered during the last minute of TU-154M aircraft flight from Warsaw to Smolensk, we show the value and existence of space for undertaking research works on enhancing standard functionality of TAWS/FMS systems to enable their effective use in examination of the course and causes of air accidents. The flight ended up in the total destruction of the aircraft and the death of all passengers and crew on board. The TAWS/FMS flight altitudes and spatio-temporal data, i.e. geographical location and speed of the aircraft motion, were inspected for their internal and external consistency with the data from the ATM QAR service recorder. Using the data from ATM QAR, records from the cockpit voice recorder (CVR), jointly with data from the TAWS/FMS systems, it was possible to reconstruct the most probable horizontal and vertical trajectory of the TU-154M aircraft during the last minute of flight before its complete destruction, as well as the likely scenario of accompanying events. The data available from recorders enabled the authors to gain information on the preliminary stage of the course of accident, and the first phase of the aircraft's destruction, resulting in serious damage of the left wing of the aircraft. Enhanced standard functionality of TAWS/FMS systems, incorporating use of their data in the post-accident situations examination, would have improved results and simplified the present analysis considerably.

This article describes the design and evaluation of a new type of propulsion mechanism that uses modular umbrella-like wings oscillating symmetrically in counterphase to generate thrust. The principle of the propulsion and movement of the modular umbrella-like wings was first developed, and the mechanism used to implement the movement of the modular wings was subsequently designed. A structural model and the assembly relationship of the propulsion mechanism were developed for prototype fabrication. An experiment was established to measure the kinematic and mechanical performances of the propulsion mechanism for different reciprocating frequencies and travels. The results for the single umbrella-like wing indicate that either increasing the frequency or enlarging the travel can enhance the average aerodynamic force generated by the wing in one cycle. The results for the modular umbrella-like wings demonstrate that the inertial force generated by the mechanism can be balanced using a symmetrical structure. The average aerodynamic force would be markedly enhanced by increasing the percentage of the time that the outspread wing is moving downwards; e.g. the average aerodynamic force generated by the modular umbrella-like wings was increased by 85.84% compared to the value for a single umbrella-like wing for the same travel and frequency. This work provides practical guidance for optimising the structure design.

The Clean Sky Joint Undertaking is currently managing two large-scale research and innovation programmes under FP7 and Horizon 2020 to contribute to the strengthening of the European aeronautical sector ensuring global leadership and competitiveness. This paper describes the research and demonstration programmes in Clean Sky (2008–2017) and Clean Sky 2 (2014–2024) related to propulsion technologies for the next-generation aircraft. The bulk of this work is addressed in Clean Sky 1 under the “Sustainable And Green Engines” (SAGE) programme and under the “ENGINES” programme in Clean Sky 2. The High-Level Objectives are described for each engine architecture as well as the targets in terms of CO2 and noise reduction versus a year 2000 reference unless stated otherwise. An overview of the new engine concepts that would satisfy the ACARE objectives is presented, including the main technologies which are to be developed to ensure the successful demonstration of each of those new engine concepts.

Recent advances in coaxial rotor design have shown benefits of this configuration. Nevertheless, issues related to rotor-head drag, aerodynamic performance, wake interference, and vibration should also be considered. Simulating the unsteady aerodynamic loads for a coaxial rotor, including the aerodynamic interactions between rotors and rotor blades, is an essential part of analysing their vibration characteristics. In this article, an unsteady aerodynamic analysis based on a vortex particle method is presented. In this method, a reversed-flow model for the retreating side of the coaxial rotor is proposed based on an unsteady panel technique. To account for reversed flow, shedding a vortex from the leading edge is used rather than from the trailing edge. Moreover, vortex-blade aerodynamic interactions are accounted for. The model considers the unsteady pressure term induced on a blade by tip vortices of other blades, and thus accounts for the aerodynamic interaction between the rotors and its contribution to the unsteady airloads. Coupling the reversed-flow model and the vortex-blade aerodynamic interaction model with the viscous vortex-particle method is used to simulate the complex wake of the coaxial rotor. The unsteady aerodynamic loads on the X2 coaxial rotor are simulated in forward flight, and compared with the results of PRASADUM (Parallelized Rotorcraft Analysis for Simulation And Design, developed at the University of Maryland) and CFD/CSD computations with the OVERFLOW and the CREATE-AV Helios tools. The results of the present method agree with the results of the CFD/CSD method, and compare to it better than the PRASADUM solutions. Furthermore, the influence of the aerodynamic interaction between the coaxial rotors on the unsteady airloads, frequency, wake structure, induced flow, and force distributions are analysed. Additionally, the results are also compared against computations for a single-rotor case, simulated at similar conditions as the coaxial rotor. It is shown that the effect of tip vortex interaction plays a significant role in unsteady airloads of coaxial rotors at low speeds, while the rotor blade passing effect is obviously strengthened at high-speed.

Among various aviation meteorological conditions, heavy rain is an important one that may seriously affect aircraft flight safety. Over the past decades, appreciable efforts have been made to study the impacts of heavy rain on aircraft flight performance. Although there has been a consistent conclusion that heavy rain can cause great static aerodynamic performance degradation, such as lift decrease and drag increase, little has been known on the effects of heavy rain on aircraft dynamic flight performance. This article explores the static and dynamic aerodynamic performance of an approximated model of the DLR-F12 transport aircraft in simulated heavy rain environment. A novel synthesised approach is proposed to study the stability dynamic derivatives in a heavy rain condition. The results suggest that heavy rain not only causes more fuel consumption to compensate the lost lift performance but also induces great dynamic flight performance degradations, especially the short-period mode performance, thus seriously threatens aircraft flight safety.

A numerical simulation has been carried out to investigate the effects of leading edge blowing upon heat alleviation on the surface of hypersonic vehicles. The initial phase of this work deals with the ability of the present CFD-based techniques to solve hypersonic flow field past blunt-nosed vehicles at hypersonic speeds. Towards this end, the authors selected three re-entry vehicles with published flow field data against which the present computed results could be measured. With increasing confidence on the numerical simulation techniques to accurately resolve the hypersonic flow, the boundary condition at the solid blunt surface was then equipped with the ability to blow the flow out of the solid boundary at a rate of at least 0.01–0.1 times the free stream (ρ∞u∞) mass flow rate. The numerical iterative procedure was then progressed until the flow at the surface matched this new ‘inviscid like’ boundary condition. The actual matching of the flow field at the ejection control surface was achieved by iterating the flow on the adjacent cells until the flow conformed to the conditions prescribed at the control surface. The conditions at the surface could be submitted as a ρ∞u∞ at the surface or could be equipped as a simple static pressure condition providing the desired flow rate. The comparison between the present engineering approach and the experimental data presented in this study demonstrate its ability to solve complex problems in hypersonic.

As simulation has become an integral part of the overall life-cycle support of aircraft, the need for effective Virtual Engineering (VE) tools to support these activities has increased. FLIGHTLAB is a state-of-the-art, aircraft modelling and simulation software tool, that has been designed to address this need and is widely used in rotorcraft design, analysis, test and evaluation, and full-flight simulation applications. This VE tool supports the development and analysis of both fixed and rotary wing aircraft with an extensive library of modelling components which have been successfully used and validated in numerous, real-world applications. These components provide comprehensive modelling of aerodynamic, structural, control and propulsion disciplines. Analyses include performance, dynamic response, stability and control, airloads, and structural loads. Graphical User Interfaces and an interactive scripting language provide user-friendly operation. This paper describes the capabilities and validation activities that have been undertaken to support the development of the commercial VE toolset FLIGHTLAB over the last 20 years and discusses future rotorcraft challenges that could be addressed by enhancements to current generation VE tools.

Advanced design offices have traditionally applied conceptual design techniques based on semi-empirical methods in an attempt to develop an accurate prediction of aircraft designs at the end of the development process. Continuing advances in computer capability and rotorcraft analysis software present an opportunity to re-think conceptual design to include the greater use of physics-based analyses. A roadmap for developing this capability is outlined, taking into account techniques and ideas from Model-Based Systems Engineering, Design Thinking and Multidisciplinary Optimisation. Recent activities that demonstrate some of these desired capabilities are briefly described along with lessons learned.

It is an enormous honour for me to take over from Peter Bearman as Editor-in-Chief of the world's oldest aeronautics journal. Most of you will not know me and thus I'd like to give you a bit of background: I grew up in Bavaria and studied Aerospace Engineering at Stuttgart University. Under the German system it was common to work on the final research project (Diploma thesis) outside the University and I was lucky enough to find a suitable place in Cranfield. There, my supervisor was John Stollery, who led this journal as Editor-in-Chief for many years. After a PhD in hypersonic aerodynamics (also at Cranfield) I became a post-doctoral researcher at Tohoku University in Japan. 18 months later I returned to the UK to take up a lectureship in aerodynamics at the Engineering Department of Cambridge University where I am now the Professor of Aerodynamics, Head of the Fluids Group and Deputy Head of Department with responsibility for graduate education.

The effect of inertial forces on the Structural Dynamics (SD) behaviour of Elastic Flapping Wings (EFWs) is investigated. In this regard, an analytical modal-based SD solution of EFW undergoing a prescribed rigid body motion is initially derived. The formulated initial-value problem is solved analytically to study the EFW structural responses, and sensitivity with respect to EFWs’ key parameters. As a case study, a rectangular wing undergoing a prescribed sinusoidal motion is simulated. The analytical solution is derived for the first time and helps towards a conceptual understanding of the overall EFW's SD behaviour and its analysis required in their designs. Specifically, the EFW transient and steady response in on-off servo condition is also attended.

Supersonic civil aircraft present a unique noise certification challenge. High specific thrust required for supersonic cruise results in high engine exhaust velocity and high levels of jet noise during take-off. Aerodynamics of thin, low-aspect-ratio wings equipped with relatively simple flap systems deepen the challenge. Advanced noise reduction procedures have been proposed for supersonic aircraft. These procedures promise to reduce certification noise levels, but they may require departures from normal reference procedures defined in noise regulations. The subject of this article is a take-off performance and noise assessment of a notional supersonic business jet. Analytical models of an airframe and a supersonic engine derived from a contemporary subsonic turbofan core are developed. These models are used to predict take-off trajectories and certification noise levels. Results indicate advanced take-off procedures are helpful in reducing noise along lateral sidelines.

The synergistic combination of two promising engine architectures for future aero engines is presented. The first is the Composite Cycle Engine, which introduces a piston system in the high pressure part of the core engine, to utilise closed volume combustion and high temperature capability due to instationary operation. The second is the Intercooled Recuperated engine that employs recuperators to utilise waste heat from the core engine exhaust and intercooler to improve temperature levels for recuperation and to reduce compression work. Combinations of both architectures are presented and investigated for improvement potential with respect to specific fuel consumption, engine weight and fuel burn against a turbofan. The Composite Cycle alone provides a 15.6% fuel burn reduction against a turbofan. Options for adding intercooler were screened, and a benefit of up to 1.9% fuel burn could be shown for installation in front of a piston system through a significant, efficiency-neutral weight decrease. Waste heat can be utilised by means of classic recuperation to the entire core mass flow before the combustor, or alternatively on the turbine cooling bleed or a piston engine bypass flow that is mixed again with the main flow before the combustor. As further permutation, waste heat can be recovered either after the low pressure turbine – with or without sequential combustion – or between the high pressure and low pressure turbine. Waste heat recovery after the low pressure turbine was found to be not easily feasible or tied to high fuel burn penalties due to unfavourable temperature levels, even when using sequential combustion or intercooling. Feasible temperature levels could be obtained with inter-turbine waste heat recovery but always resulted in at least 0.3% higher fuel burn compared to the non-recuperated baseline under the given assumptions. Consequently, only the application of an intercooler appears to provide a considerable benefit for the examined thermodynamic conditions in the low fidelity analyses of various engine architecture combinations with the specific heat exchanger design. Since the obtained drawbacks of some waste heat utilisation concepts are small, innovative waste heat management concepts coupled with the further extension of the design space and the inclusion of higher fidelity models may achieve a benefit and motivate future investigations.

This paper investigates the impact of the wall-heating conditions on the heat transfer performance of a rotating channel with one side smooth and one side roughened by 45° inclined ribs. Previous experimental and numerical studies for single-ribbed wall-heated channels showed that rotation has a significant negative impact on heat transfer performance. In order to investigate this uncommon behaviour, RANS simulations were conducted under three different wall-heating conditions in the present study: ribbed wall heated, all walls heated and adiabatic conditions. Numerical results show that the presence of uneven wall-heating conditions has a negligible impact on the stationary case, but it has a large influence on rotational cases, in both, the heat transfer and the flow field. The underlying reason is that in rotating cases, uneven heating results in different buoyancy effects on the trailing and leading walls of the channel that alter the main flow velocity profile. As a consequence, also secondary flows and heat transfer performance are affected.

This paper proposes an adaptive guidance law for attacking a ground target based on motion camouflage strategy. The coefficients of normal and bi-normal feedback guidance law are given according to the relative motion relationship under Frenet frame. Utilizing the coefficients, the motion camouflage proportional guidance law is derived. In order to improve the initial overload characteristic of the missile, an adaptive feedback coefficient is introduced. Then, the adaptive guidance law is applied to a longitudinal plane interception problem with impact-angle constraint. Finally, the validity of this guidance law for air-to-ground missiles is proved by simulations.

This investigation surveyed the potential and established outcomes for future 19-passenger fixed-wing commuter transport aircraft concepts employing battery-based Voltaic-Joule/Brayton motive power systems with no additional electrical energy drawn from generators mechanically coupled to thermal engines. The morphological approach was that of a tri-prop (two on-wing podded turbo-props and one aft-fuselage mounted electric motor configured as a pusher-on-pylon installation). A Battery System-level Gravimetric Specific Energy (referred to as “battery energy density”) of at least 500 Wh/kg yielded 39%, 25% and 10% block fuel reductions for 150-nm (Design Service Goal), 430-nm (85th percentile) and 700-nm (maximum range) stage lengths, respectively. All quoted comparisons are against a suitably projected turbo-prop only year-2030 aircraft. In contrast to the reference Beech 1900D, block fuel reductions of up to 44-49% were predicted, which could facilitate a significantly lower deficit in relation to the Advisory Council for Aviation Research and Innovation in Europe (ACARE) Strategic Research and Innovation Agenda (STRIA) 55% target for year 2030. This investigation also indicated that, in the future, suitably flexible hybrid-electric architectures could be fashioned allowing possibility for the aircraft to complete any required city-pair operations (within the legitimate payload-range working capacity) irrespective of exchangeable batteries being available at a given station. Finally, it was also established, assuming such a tri-prop morphology, Normal conducting machines delivering maximum shaft power output of 1.1 MW would be required.

The geometry of a planar converging-diverging nozzle operating with dry air in dilute gas conditions is modified by the introduction of a small recessed step at the throat section. Pressure measurements along the nozzle axis, schlieren visualisations and numerical simulations are performed to investigate the influence of the recessed step on the supersonic flow-field. In the experiments, the height of the recessed step is 0.1 mm and the nozzle height at the throat is 10 mm. Numerical simulations examine also 0.05 mm and 0.2 mm step heights. From the numerical simulations, the flow Mach number at the step location is 1.04 and the Reynolds number computed using the sonic conditions and the throat half-height is Re = 3.73 × 105. A perturbation wave pattern originates from the step, which results in a perturbation of the measured pressure profile close to the throat section. In the diverging portion, sufficiently far from the throat section, the pressure profile of the recessed-step nozzle matches the one measured in the clean configuration.

There is a wide variety of CFD grid types including Cartesian, structured, unstructured and hybrids, as well as, numerous methodologies of combining these to reduce the time required to generate high-quality grids around complex configurations. If the grid methodologies were implemented in different codes, they should be written in such a way as to obtain the maximum performance from the available computer resources. A common interface should also be required to allow for ease of use. However, it is very time consuming to develop, maintain and add extra functionally to different codes. This paper examines the possibility of taking an existing CFD solver, the Helicopter Multi-Block (HMB) CFD method, and implementing a new grid type while reusing as much as possible the original code base. The paper presents some of the challenges encountered in extending the code which was written for a single mesh type, to a more flexible solver that is still computationally efficient but can cope with a variety of grid types.