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The main purpose of this paper is to investigate the effects of icing on unmanned aerial vehicles (UAVs) at low Reynolds numbers and to highlight the differences to icing on manned aircraft at high Reynolds numbers. This paper follows existing research on low Reynolds number effects on ice accretion. This study extends the focus to how variations of airspeed and chord length affect the ice accretions, and aerodynamic performance degradation is investigated.

A parametric study with independent variations of airspeed and chord lengths was conducted on a typical UAV airfoil (RG-15) using icing computational fluid dynamic methods. FENSAP-ICE was used to simulate ice shapes and aerodynamic performance penalties. Validation was performed with two experimental ice shapes obtained from a low-speed icing wind tunnel. Three meteorological conditions were chosen to represent the icing typologies of rime, glaze and mixed ice. A parameter study with different chord lengths and airspeeds was then conducted for rime, glaze and mixed icing conditions.

The simulation results showed that the effect of airspeed variation depended on the ice accretion regime. For rime, it led to a minor increase in ice accretion. For mixed and glaze, the impact on ice geometry and penalties was substantially larger. The variation of chord length had a substantial impact on relative ice thicknesses, ice area, ice limits and performance degradation, independent from the icing regime.

The implications of this manuscript are relevant for highlighting the differences between icing on manned and unmanned aircraft. Unmanned aircraft are typically smaller and fly slower than manned aircraft. Although previous research has documented the influence of this on the ice accretions, this paper investigates the effect on aerodynamic performance degradation. The findings in this work show that UAVs are more sensitive to icing conditions compared to larger and faster manned aircraft. By consequence, icing conditions are more severe for UAVs.

Atmospheric in-flight icing is a severe risk for fixed-wing UAVs and significantly limits their operational envelope. As UAVs are typically smaller and operate at lower airspeeds compared to manned aircraft, it is important to understand how the differences in airspeed and size affect ice accretion and aerodynamic performance penalties.

Earlier work has described the effect of Reynolds number variations on the ice accretion characteristics for UAVs. This work is expanding on those findings by investigating the effect of airspeed and chord length on ice accretion shapes separately. In addition, this study also investigates how these parameters affect aerodynamic performance penalties (lift, drag and stall).

Ice formation constitutes a hazard to aircraft operation both on the ground and in flight. This article deals with the protection of aircraft against ice formation in flight, but does not consider the counter measures which must be taken on the ground in winter conditions. The first part of the paper deals with the atmospheric conditions which give rise to ice accretion on forward facing surfaces and the types of ice which form at various ambient temperatures. A general survey is then made on methods of solving the problem and the weight and power penalties which they entail. Finally some recent developments in the electrical deicing systems arc reviewed.

The performance criterion for engine power for aircraft of the Skyvan type is related to the single engine climb gradient in the en route configuration. The required engine power (M.C.P.) was specified such as to give a payload capability of 3,500 lb. at an ambient condition of ISA plus 20 deg. C. By use of such a specification the effects of different engine bulk, weight and individual engine installation deficiencies were included in the assessment. The Garrett 331–201 engine was chosen, as far as aerodynamic considerations were concerned, because the required power was immediately available on then current development engines, substantiated by test bed data. In addition the installation was most suitable to the underslung position on Skyvan in that the nacelle lines, though severe, were acceptable, and the straight through exhaust system was preferred. The anti‐icing system of the Garrett gives no performance penalty in the ‘anti‐icing off’ configuration as related to certification performance, and was already certificated on the Volpar aircraft at that time.

Describes a technique, currently used at General Motors, which contains some of the elements of operations research and has effected important reductions in costs. The technique contains seven steps: (i) determine problem or objective, (ii) study conditions existing, (iii) plan possible solutions, (iv) evaluate possible solutions, (v) recommend action, (vi) follow up to assure action, (vii) check results. The procedure followed at each step is outlined. The investigation is carried out by a special Planning Team. This team consults other staff involved as may be necessary. During any investigation of existing plant the aim is that production should continue at a minimum cost.

THE ice protection system chosen by Vereinigte Flugtechnische Werke‐Fokker GmbH for the airframe of their VFW 614 aircraft is a T.K.S. fluid system. This system, which is similar to that used, for example on the HS 125, works on the principle of forming a film of Glycol based freezing point depressant fluid over the protected surfaces. This film of ‘de‐icing’ fluid combats ice formation by both melting the ice (or preventing freezing of supercooled water droplets) and by preventing adhesion of any ice that does form. Hence, the system can be operated in a de‐icing or anti‐icing mode.

This paper contains a broad discussion of some of the more important structural problems in high per‐formance aircraft and some of the methods and materials currently available to the aircraft designer for their solution. The constant demand for refined design and advanced performance has brought new modes of failure and new prominence for classic phenomena such as thermal stresses, creep, nuclear radiation, fatigue, elastic effects and transient stresses. These phenomena are discussed and some observa‐tions on the means of coping with them are included. Man‐power utilization, organizational refinements, computing machinery, flight load measurements, structural testing facilities and stress analysis data are the devices discussed from this standpoint. An im‐posing array of materials is at the disposal of the air‐craft designer and new materials being developed to improve structural efficiency and to help in sur‐mounting the difficulties of higher performance. High heat‐treated steel, 78ST, titanium and certain plastics are discussed briefly, and some potentialities for the future are mentioned. It is concluded that powerful tools are available to provide safe, efficient and prac‐tical structures for high performance aircraft and that structures can keep pace with developments in the science of flight.

In introducing the subject some of the advantages of pneumatics for high speed aircraft are pointed out. Owing to its suitability for airborne conditioning systems, it is pointed out that it is logical to combine this characteristic in producing a combined air turbine and electric generator without the need of a separate cooling system. This was the thought behind the design of the Turbonator AC generating machine It includes a turbine wheel integral with the generator which is arranged to allow the turbine exhaust gas to pass over the generator for cooling purposes. The generator rotor windings are supported solidly by titanium retainers. Rotor bearings may either be of the sealed oil type or air bearings. Both have been tested, but, while the former is the simplest and suitable for present‐day standards, the air bearing has distinct possibilities for future uses. Thrust loads are taken up by an air bearing using the turbine wheel face as the bearing journal. No liquid is therefore used as a lubricant, thereby eliminating this high temperature problem. Materials for the generator are considered, one of which is ceramic insulation. Consideration was given to the inductor generator, but although this type of machine may be more suitable for high speeds, the rotating winding generator displays more advantages. A test rotor of the latter type has withstood speeds of 62,000 r.p.m. which is 25 per cent above normal speeds. The recent availability of a 24,000 r.p.m. generator makes it possible to eliminate a reduction gear.

TURBO‐UNION LIMITED, a joint company set up by Rolls‐Royce in the UK, Motoren‐ und Turbinen Union in West Germany, and Fiat in Italy, is reponsible for design, development and manufacture of the RB 199 engine powering the European multi‐role combat aircraft.

In order to succeed in an action under the Equal Pay Act 1970, should the woman and the man be employed by the same employer on like work at the same time or would the woman still be covered by the Act if she were employed on like work in succession to the man? This is the question which had to be solved in Macarthys Ltd v. Smith. Unfortunately it was not. Their Lordships interpreted the relevant section in different ways and since Article 119 of the Treaty of Rome was also subject to different interpretations, the case has been referred to the European Court of Justice.

The problem of hydrogen embrittlement has been approached in a less theoretical manner than in some previous investigations. Factors were considered which could be utilized to minimize embrittlement in processing especially with the higher strength steels which suiter mostly.