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This is the second of two companion papers presenting the results of research into a contra‐rotating propeller designed to drive a super manoeuvrable micro air vehicle (MAV) and is devoted to the experimental results. The first paper presented the design process and numerical analyses.

Most of experiments were conducted in the wind tunnel. Both contra‐rotating and conventional propellers were tested. The test procedures and equipment are described first. The attention is focused on the design of an aerodynamic balance used in the experiment. Then, the measurement error is discussed, followed by presentation of the wind tunnel results. Finally, an initial flight test of the MAV equipped with contra‐rotating propeller is briefly described.

Wind tunnel experiment results fall between theoretical results presented in the first part of the paper. The application of contra‐rotating propeller allowed to develop the propulsion system with zero torque. Moreover, the efficiency achieved appeared to be a few percent greater than that for a standard conventional propulsion system. The concept was finally proved during the first test flight of the new MAV.

The propeller was designed for a fixed wing aeroplane, not for helicopter rotor. Therefore, only conditions characteristic for fixed wing aeroplane flight are tested.

The designed contra‐rotating propeller can be used in fixed wing aeroplane if torque equal to zero is required.

Original design of the balance is described for the first time, as well as test procedures applied in this experiment. Most of wind tunnel test results are also new and never published before.

The purpose of this paper is to present a procedure to design an experimental setup meant to validate an innovative approach for simulating, via computational fluid dynamics, a high-pressure gas release from a rupture (e.g. on an offshore oil and gas platform). The design is based on a series of scaling exercises, some of which are anything but trivial.

The experimental setup is composed of a wind tunnel, the instrumented scaled (1:10) mock-up of an offshore platform and a gas release system. A correct scaling approach is necessary to define the reference speed in the wind tunnel and the conditions of the gas release to maintain similarity with respect to the real-size phenomena. The scaling of the wind velocity and the scaling of the gas release were inspired by the approach proposed by Hall et al. (1997): a dimensionless group was chosen to link release parameters, wind velocity and geometric scaling factor.

The theoretical scaling approaches for each different part of the setup were applied to the design of the experiment and some criticalities were identified, such as the existence of a set of case studies with some release parameters laying outside the applicability range of the developed scaling methodology, which will be further discussed.

The resulting procedure is one of a kind because it involves a multi-scaling approach because of the different aspects of the design. Literature supports for the different scaling theories but, to the best of the authors’ knowledge, fails to provide an integrated approach that considers the combined effects of scaling.

The purpose of this paper is to numerically and experimentally evaluate the effect of the protection net icing on the inlet performance of helicopter engines.

The ice shapes of the protection net at different times are first simulated by a two-dimensional (2D) icing calculation, then the porous media parameters are calculated based on the 2D ice shapes. Afterward, three-dimensional flow fields of the engine inlet with the iced net are simulated using the porous media model instead of the real protection net. The transient pressure losses of the iced protection net are calculated and tested through an icing wind tunnel test rig under different icing conditions.

Overall, the numerical results and experimental data show a good agreement. The effects of several control parameters, such as liquid water contents (LWC), water droplet diameters and airflow velocities on the pressure loss of the protection net during the icing process are analyzed in a systematic manner. The results indicate that the pressure loss increases with the increase of the LWC at the same icing time. The same trend occurs when the water droplet diameter and the airflow velocity increase.

A new method to predict the pressure loss of the iced protection net is proposed. A series of tests in an icing wind tunnel are performed to obtain the ice shapes and pressure loss of protection net during the icing process.

The purpose of this paper is to develop a propeller performance measurement method for high-altitude platforms by analyzing of the propeller aerodynamic characteristics and application of a mobile testing system.

An experimental approach is adopted for this study. Considering the aerodynamic characteristics of the high-altitude propeller, the similitude of the scaled propeller model in the experiment is analyzed and determined. Then, the experimental method and procedure to obtain the propeller’s performance under different altitudes are presented, and the structure of hardware and software and the key techniques of the testing system are introduced in detail.

The applicability and effectiveness of the testing system is verified through comparison between experimental and numerical results. In addition, the performance of the 6.8-m propeller for a high-altitude airship is tested, which proves that the high-altitude propeller can meet the requirements of the propulsion system.

The testing methodology and the mobile testing system could be applied to aerodynamic performance evaluation of the high-altitude propellers under different altitudes.

This testing approach exhibits significant time and cost benefits over many other experimental methods to obtain the performance of the high-altitude propellers, which is important in the preliminary design of the propulsion system for high-altitude platforms.

THE authorities of the Institute of the Aeronautical Sciences have decided, so I am instructed, that the Wright Brothers' Lecture should deal with subjects upon which the lecturer is engaged at the time, rather than with a general survey of some wide branch of aeronautical knowledge. This decision has the advantage that the lecturer is actively interested in the subject about which he talks, but it leaves to chance the question whether he is in a position to end his lecture with simple and clear cut conclusions. I mention this because the problem upon which we are working at Cambridge, and about which I shall speak, is not yet solved and my lecture must, perforce, be confined to a discussion of aims and methods and of results so far obtained; it does not contain that simple statement of conclusions which is the ultimate aim of all good research. After this explanation you will not, I hope, be disappointed when the lecture ends on a note of interrogation.

THE development of modern aeroplanes designed for high speeds, with their thin, almost symmetrical wing sections, has led inevitably to high landing speeds and small gliding angles with the normal wing arrangement.

The purpose of this paper is to describe the research performed on flexible-wing micro air vehicle (MAV). Typical attributes associated with the aerodynamics of MAVs are low Reynolds number, low altitude flying environments and low aspect ratio platforms. These attributes give birth to several challenges such as poor aerodynamic performance, nonlinear lift patterns and reduced gust tolerance. Flexible-wing MAV is renowned for improved aerodynamic characteristics such as smooth flight in gusty conditions than its rigid-wing counterpart.

The wind-tunnel experiments are carried out for various configurations to determine the ways of further enhancing lift. The baseline geometric description for all MAVs includes 15-cm box dimension and an aspect ratio of 1. The experimental results of the baseline configuration are compared with other experimental results available in literature. After due validation, the effects of following parameters are quantized and compared with the rigid-wing counterpart: underlying skeleton; wing membrane extension; wing membrane relaxation; and wing membrane material (latex, silk, poly-vinyl chloride plastic sheet and nylon).

It is found that the skeleton layout significantly governs the lift characteristics. The effect of membrane extension and relaxation proved to be of little advantage. Latex sheets are found to be the best choice for membrane material. The aerodynamic assessment at low Reynolds number has demonstrated significant improvement of lift characteristics for flexible wings over rigid-wing counterparts.

The results presented in this paper are based on wind-tunnel experimentation. Further experimentation through flight test may be needed to reveal the true aerodynamic performance under unsteady maneuvers.

The material properties vary significantly during fabrication. A technique to standardize the properties of flexible membranes is a missing link in literature and warrants further investigation.

This concept of flexible wing has shown high potential. The primary objective of this paper is to experimentally investigate ways of further enhancing the lift of flexible-wing MAVs by controlling flexibility passively. While various researchers have spent many years on developing the optimum wing frame for the flexible wing, research on different wing materials has been limited. This is the first paper of its kind covering all aspects of wing-frame design, material, effects of extension and relaxation on wing membrane.

This paper describes a series of tests of remotely piloted vehicles (RPV) and full scale aircraft from which most of the performance information and selected dynamic characteristics normally required for aircraft operation can be obtained. The main goal of the paper is to compare corresponding characteristics of RPVs and full scale aircraft and establish if RPV testing can help and influence an early stage design project in order to optimise its aerodynamic configuration and predict its static and dynamic characteristics. This paper presents basic similarity transformations, including mass scale, force scale, power scale, linear acceleration scale, Reynolds number scale etc. as functions of linear scale. It was found that tests in steady conditions are difficult to perform, time‐consuming, and do not offer significant advantages over the classical wind tunnel tests. RPV tests in unsteady conditions are much easier to perform and quite accurate.

THE fact that ring cowling is approved for use with the current series of Mercury and Pegasus engines appears a suitable occasion for a resumé of the important development work carried out by the Bristol Company in connection with the application of drag‐reducing cowlings to their engines and a programme of work which has included a long series of single cylinder experiments, wind tunnel research and full scale flight tests.

THE present paper deals with a semi‐empirical method of using airscrew strip theory to take account of the mutual interference of a body and tractor airscrew. It also contains a brief account of the successive wind tunnel experiments, starting from the original tests of the “family of airscrews,” which have led up to the theory and which provide the evidence for its accuracy over the somewhat limited range which they cover. The majority of the work has been published at intervals extending over the past six years, and I have to thank the Aeronautical Research Committee for permission to include some recent experimental work not yet published.