The aerodynamic flow conditions on wings and tail surfaces due to the rotational motion of a spinning aeroplane have been investigated in a full-scale spin flight research programme at the Brunel Flight Safety Laboratory. The wing upper surface vortex has been visualised using smoke and tufts on the wing of a Slingsby Firefly. The flow structures on top of both wings, and on top of the horizontal tail surfaces, have also been studied on a Saab Safir. The development of these rotational flow effects has been related to the spin motion and the effect on the spin dynamics has been studied and discussed. Evidence suggests that the turbulent wake from the wing upper surface vortex impinges the tail of the aircraft during the spin entry. It is hypothesised that the turbulent flow structure on the outside upper wing surface is due to additional accelerations induced by the rotational motion of the aeroplane. Furthermore, the lightening in stick force during spin entry and the apparent increase in push force required for spin recovery corresponds to the observed change in flow condition on the horizontal tail. The difference in pressure on the upper and lower horizontal tail surfaces have been measured using differential pressure sensors, and the result corresponds both with the observed flow conditions and earlier research results from NASA.

An experimental investigation has been carried out to study the effect of notches on the flow and noise characteristics of 2:1 elliptic-slot jets. The effect of variation in notch geometry is also investigated. The presence of the notch is found to provide low-velocity regions in the notched-minor-axis plane thereby intensifying the jet growth along that plane. The interaction of these low-velocity regions with the mean flow results in shorter core-lengths. At under-expansion, the shock-cell lengths are weakened considerably in notched jets resulting in significant reductions in the overall jet noise level. Azimuthal directivity of elliptic jets indicate higher noise intensity radiated along major-axis ends relative to minor-axis sides. Notches seem to circumferentially modify the noise emission characteristics and significantly bring down the noise levels along major-axis-unnotched plane. Polar directivity indicates reduction in both shock noise and jet mixing noise in the forward quadrant.

The objective of the work described in this paper was to identify differences in the flow fields immediately downstream of air-jet and vane vortex generators. The flows were assumed to be incompressible and fully turbulent and were solved using the finite volume, Navier-Stokes code CFX 4 (CFDS, AEA Technology, Harwell) on a non-orthogonal, body-fitted grid using the k-ε turbulence model and standard wall functions. The behaviour of the longitudinal vortices produced by the vanes and air jets is presented in terms of stream-wise and cross-stream velocity profiles, circulation and peak vorticity decay, peak vorticity paths in the cross-stream and streamwise direction, cross-stream vorticity profiles, and cross-stream distribution of shear stress. The predicted results show that the vanes and air jets considered produce vortices with significantly different circulation strengths, but that the enhancement of skin friction was of similar magnitude in both cases.

In some space applications, such as satellite surveillance and communication, a spacecraft must perform accurate pointing and slewing manoeuvres, whereby the spacecraft is rotated along a large angle amplitude trajectory. In many circumstances it is also required that the sensitive payload does not intercept bright objects such as the Sun, Earth and Moon, to avoid possible damage to the optical instruments. The importance of this subject has stimulated an active research, and different approaches have been reported in the literature(1-5).

The arrival on the aeronautical scene of a new generation of propeller driven commercial aircraft, and the great interest in the propeller as an economical means of propulsion for high subsonic Mach numbers, makes this an appropriate time to look back and attempt to identify some of the evolutionary paths by which the present state of development has been reached.

A consideration of the history of the propeller may be confined to the period beginning around the late eighteenth and early nineteenth century, when the propeller was clearly recognisable as such and becoming established. However, the idea goes back many centuries before this and there is a wealth of references describing, not always very precisely, various mechanical devices intended or actually used for ship propulsion which may be considered remote but legitimate ancestors of the present day propeller. Before considering more recent developments, it is worth looking at the beginnings of mechanical propulsion if only to pay tribute to those early engineers who did not allow the lack of suitable materials or theory to inhibit their attempts.

A re-cooled cycle has been proposed for a regeneratively cooled scramjet to reduce the hydrogen fuel flow for cooling. Upon the completion of the first cooling, fuel can be used for secondary cooling by transferring the enthalpy from fuel to work. Fuel heat sink (cooling capacity) is thus repeatedly used and fuel heat sink is indirectly increased. Instead of carrying excess fuel for cooling or seeking for any new coolant, the cooling fuel flow is reduced, and fuel onboard is adequate to satisfy the cooling requirement for the whole hypersonic vehicle. A performance model considering flow and heat transfer is build. A model sensitivity study of inlet temperature and pressure reveals that, for given exterior heating condition and cooling panel size, fuel heat sink can be obviously increased at moderate inlet temperature and pressure. Simultaneously the low-temperature heat transfer deterioration and Mach number constrains can also be avoided.

It is now the usual practice in Great Britain to estimate the “ safe ” life of an aircraft wing from fatigue tests which are carried out on specimens representing the more highly stressed portions of the tension boom or booms. Such tests are designed to produce a tensile load in the boom equal to that produced in steady flight, and superimposed on this, a small fluctuating load corresponding to that which would be produced by an up gust immediately followed by a down gust of the same magnitude.

This Convention poses a challenge to the lecturers. It asks us to gaze into a crystal ball and to forecast the future on the basis of the research of today. My contribution is to review the aerodynamics scene. I am the first specialist lecturer; this is perhaps a recognition that many of the significant advances of the past have been aerodynamically inspired. It is natural to start by thinking back 20 years and asking whether we would then have predicted what has come true today. In aerodynamics, there is obviously a clear answer to this question.

This paper looks at active control of the normal shock wave/turbulent boundary layer interaction (SBLI) using smart flap actuators. The actuators are manufactured by bonding piezoelectric material to an inert substrate to control the bleed/suction rate through a plenum chamber. The cavity allows rapid thickening of the boundary-layer approaching the shock, which splits into a series of weaker shocks forming a lambda shock foot, thus reducing wave drag. Active control allows optimisation of the interaction, as it would be capable of either positioning the control region around the original shock position using a series of unimorph flaps or fixing the shock position by controlling the rate of mass transfer.

The level of control achieved by unimorph piezoelectric actuators is not large because of small amounts of deflection possible. It is believed that to provide optimal control a piezoelectric material, which can provide greater strain and hence higher amounts of deflection is needed. However, currently such a piezoelectric material is not commercially available.

The first supersonic business jet to enter the market will not face its competition from rival supersonic designs under development. Its true competitors are the then current generation of highly evolved high-subsonic business jets when compared on economic grounds. For a price tag of $1m for the new conception of very light jets, ranging up to $45m for the highest-performing ‘race-horse’-like corporate jets, this breed of aircraft is able to accommodate the needs of most executives, VIPs, officials, from corporate transportation to cargo services of civil to military origin. Understanding the state of modern business class aircraft and their market is essential in gaining base knowledge required for any supersonic business jet endeavor aiming at a prospective market. The key descriptors for this marketplace are market potential, market productivity, and market drivers, altogether being a measure for growth and consumer demand. Such common denominator is used to gain the understanding necessary to ascertain and visualise the top level implications regarding any supersonic business case. Having assembled an understanding of the key descriptors for business aviation, the study first analyses the flight operation of traditional subsonic and high-subsonic business jets. Such perceptive is then complemented with the peculiarities associated with supersonic operation, ultimately defining the supersonic solution space consisting of market viability, efficiency, and overall flight performance. Consequently, a vehicle development strategy and mission specification are suggested for the first generation of supersonic business jets (SSBJ) and supersonic cargo jets (SSCJ).

Turbulent motion in open air must be studied in a way differing from that followed in laboratory experiments. We cannot choose or arrange for the most suitable conditions; we have to make the best of what nature offers; it is nearly impossible to stain air masses sufficiently so that they show streamlines-we have to judge their possible form from complicated effects. The results arrived at will depend upon the means at one's disposal and the way pursued.

This paper presents the design, development and construction of a flight test stand for a quadrotor UAV. As opposed to alternate forms of UAV, the power plant in the case of the quadrotor serves a dual purpose of control and propulsion. Since control and propulsion are coupled, the power plant (BLDC motor coupled with propeller) was studied in detail using a black box structure. Extractions of motor parameters in previous studies used traditional BLDC motor equations and propeller theory however the accuracy achievable and confidence in the extracted parameters remained questionable. The developed data acquisition process served to satisfy this need by the construction of a test bench that allows for the extraction of the unknown parameters instilling confidence in the modelling process. The established relationships are then used as inputs into a developed six degree of freedom Euler based mathematical model. A mission profile was constructed with distinct phases of which the mathematical model was used to simulate. Each phase in the mission profile excited different modes of the quadrotor dynamics creating an ideal simulation environment in which changes can be implemented and studied.

A theory of primary failure of compression panels of integral construction with unflanged stiffeners is presented, involving rotation, or translation, or rotation and translation of the stiffeners with the corresponding distortion of the sheet without deformation of the cross sections in their own planes. The investigation shows that the failure may occur generally either by pure torsion of the stiffener with the associated lateral distortion of the sheet or by pure flexure in accordance with whichever mode yields a smaller stress. The theory is compared with the test results covering a fairly wide range of the dimensions involved. The theory is in complete agreement with the experiments. The accuracy of the result thus obtained indicates that the fillets at the junction of the skin and the stiffener are not important and their effects may safely be disregarded.

More than two years ago Pollard in a paper given to the Society made out the case for the use of fibre-reinforced plastics in the structural field. He and others have shown that materials based on strong, inert fibres, such as glass or asbestos, have mechanical properties which, when stabilised by suitable resins, permit them to function with a high degree of efficiency within certain well defined parameters of loading.

Four distinct groups of resin are used in combination with such fibres, phenolic, polyester, epoxide and silicone. With the present exception of silicone resins, each can be used at low or even contact pressures during moulding and thus do not impose serious processing limitation upon the size, quantity or complexity of the structures which can be contemplated.

Following the Second World War, agricultural aircraft use increased rapidly in the United States, but appears to have levelled off in the past five years. California is one of the largest users of agricultural aircraft of any State, with an estimated 8 million acres treated per year. This figure includes all applications of insecticides, fungicides, and herbicides, plus seeding, fertilising, and defoliation of agricultural crops, grasslands and forest areas. Also, this figure represents acres covered and includes duplicated applications. Certain crops, such as cotton, may have as many as four or five separate treatments during the season.

Stiffened panels usually consist of a skin of uniform thickness with several identical equally spaced longitudinal stiffeners. This paper demonstrates that the weight of a panel which is designed to have a specified initial buckling load, in uniform longitudinal compression, can be reduced by using more than one size of stiffener.

Initial buckling stresses quoted were all obtained using the computer program VIPAL, which is based on a recent “exact” method which allows for coupling between all possible modes. In this method the panel is considered as an assembly of thin uniform flat rectangular plates which are rigidly connected together along their longitudinal edges and are simply supported at their ends. The in-plane destabilising effects of the longitudinal compressive stress on the behaviour of these plates are included.

One of the most resent efforts in aircraft design is the replacement of aluminium structures by carbon fibre reinforced polymer composites. Due to lower material and manufacturing costs, doubly curved shapes covering big areas are preferred over simpler surfaces which integrate stiffening profiles. In this context, CAD parameterisation of surfaces allows design solutions by means of classical shape optimisation. Related geometrical parameters are manipulated towards optimal design, generating innovative geometries and detailing.

The presented structure is optimised by reducing the overall weight. The final optimum is guided using stability and strength restrictions in order to assure the safety of the component. Geometrical considerations are also included due to operational reasons. A hierarchical design procedure is developed which results in a work flow from preliminary ‘parameter-free’ form finding motivated by solving the minimal surface problem. The geometrical model for optimisation is recovered by generating B-Spline surface patches to preserve continuity requirements over large regions. The number of geometrical coefficients are defined by the accuracy in surface generation and the required freedom in surface control. The hierarchical approach reduces the possibilities of ending with an unsatisfactory optimum when several local minima characterise the non-linear problem, as it is usually the case in shape optimal design. A geometrical non-linear analysis is used to verify the performance of the optimum.

The rotorcraft industry needs Virtual Engineering first to ensure decisions made early in the life-cycle, at the requirements capture and preliminary design phases for example, are reliably informed. Later, in design, development and qualification, Virtual Prototypes can become the centre of attention for critical reviews and, ultimately, certification itself. A significant challenge is to ensure that model fidelity is good enough, not only for supporting design decisions but also in establishing requirements based on sufficiently mature technologies. This international conference, Rotorcraft virtual engineering; supporting life-cycle engineering through design and development, test and certification and operations and co-sponsored by the RAeS/AHS/A3F/DGLR/AIDAA addressed these themes and this paper reviews and assesses the value of the various contributions.