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The purpose of this paper is to present the aerodynamic blade design of a tiltwing aircraft with a multi-objective optimization procedure. The aerodynamic design of tiltrotor blades is a very challenging task in the project of this type of aircraft.

Tiltrotor blades have to give good performance both in helicopter and aeroplane modes. According to the design parameters (the chords, the twists and the airfoils along the blade), as the optimization objectives are different from one operating condition to another, the blade is the result of a multi-objective constrained optimization based on a controlled elitist genetic algorithm founded on the NSGA-II algorithm. The optimization process uses a BEMT solver to compute rotor performance. To avoid negative effects due to compressibility losses in aeroplane mode, the blade shape has been refined following the normal Mach number criterion.

It has been found that the optimized rotor blade gives good performance both in terms of figure of merit and propulsive efficiency if compared with experimental data of existing rotor (ERICA tiltrotor) and propeller (NACA high-speed propeller).

The optimization procedure described in this paper for the design of tiltrotor blades can be efficiently used for the aerodynamic design of helicopter rotors and aircraft propellers of all typology.

In this work, advanced methodologies have been used for the aerodynamics design of a proprotor optimized for an aircraft which belongs to the innovative typology of high-performance tiltwing tiltrotor aircraft.

In 1899 the medical practitioners of Dublin were confronted with an outbreak of a peculiar and obscure illness, characterised by symptoms which were very unusual. For want of a better explanation, the disorder, which seemed to be epidemic, was explained by the simple expedient of finding a name for it. It was labelled as “beri‐beri,” a tropical disease with very much the same clinical and pathological features as those observed at Dublin. Papers were read before certain societies, and then as the cases gradually diminished in number, the subject lost interest and was dropped.

The latest information from the magazine chemist is extremely valuable. He has dealt with milk‐adulteration and how it is done. His advice, if followed, might, however, speedily bring the manipulating dealer before a magistrate, since the learned writer's recipe is to take a milk having a specific gravity of 1030, and skim it until the gravity is raised to 1036; then add 20 per cent. of water, so that the gravity may be reduced to 1030, and the thing is done. The advice to serve as “fresh from the cow,” preferably in a well‐battered milk‐measure, might perhaps have been added to this analytical gem.

There are very few individuals who have studied the question of weights and measures who do not most strongly favour the decimal system. The disadvantages of the weights and measures at present in use in the United Kingdom are indeed manifold. At the very commencement of life the schoolboy is expected to commit to memory the conglomerate mass of facts and figures which he usually refers to as “Tables,” and in this way the greater part of twelve months is absorbed. And when he has so learned them, what is the result? Immediately he leaves school he forgets the whole of them, unless he happens to enter a business‐house in which some of them are still in use; and it ought to be plain that the case would be very different were all our weights and measures divided or multiplied decimally. Instead of wasting twelve months, the pupil would almost be taught to understand the decimal system in two or three lessons, and so simple is the explanation that he would never be likely to forget it. There is perhaps no more interesting, ingenious and useful example of the decimal system than that in use in France. There the standard of length is the metre, the standard of capacity the cubic decimetre or the litre, while one cubic centimetre of distilled water weighs exactly one gramme, the standard of weight. Thus the measures of length, capacity and weight are most closely and usefully related. In the present English system there is absolutely no relationship between these weights and measures. Frequently a weight or measure bearing the same name has a different value for different bodies. Take, for instance, the stone; for dead meat its value is 8 pounds, for live meat 14 pounds; and other instances will occur to anyone who happens to remember his “Tables.” How much simpler for the business man to reckon in multiples of ten for everything than in the present confusing jumble. Mental arithmetic in matters of buying and selling would become much easier, undoubtedly more accurate, and the possibility of petty fraud be far more remote, because even the most dense could rapidly calculate by using the decimal system.

IN order to be able to discriminate with certainty between butter and such margarine as is sold in England, it is necessary to carry out two or three elaborate and delicate chemical processes. But there has always been a craving by the public for some simple method of determining the genuineness of butter by means of which the necessary trouble could be dispensed with. It has been suggested that such easy detection would be possible if all margarine bought and sold in England were to be manufactured with some distinctive colouring added—light‐blue, for instance—or were to contain a small amount of phenolphthalein, so that the addition of a drop of a solution of caustic potash to a suspected sample would cause it to become pink if it were margarine, while nothing would occur if it were genuine butter. These methods, which have been put forward seriously, will be found on consideration to be unnecessary, and, indeed, absurd.

A pæan of joy and triumph which speaks for itself, and which is a very true indication of how the question of poisonous adulteration is viewed by certain sections of “the trade,” and by certain of the smaller and irresponsible trade organs, has appeared in print. It would seem that the thanks of “the trade” are due to the defendants in the case heard at the Liverpool Police Court for having obtained an official acknowledgment that the use of salicylic acid and of other preservatives, even in large amounts, in wines and suchlike articles, is not only allowable, but is really necessary for the proper keeping of the product. It must have been a charming change in the general proceedings at the Liverpool Court to listen to a “preservatives” case conducted before a magistrate who evidently realises that manufacturers, in these days, in order to make a “decent” profit, have to use the cheapest materials they can buy, and cannot afford to pick and choose; and that they have therefore “been compelled” to put preservatives into their articles so as to prevent their going bad. He was evidently not to be misled by the usual statement that such substances should not be used because they are injurious to health— as though that could be thought to have anything to do with the much more important fact that the public “really want” to have an article supplied to them which is cheap, and yet keeps well. Besides, many doctors and professors were brought forward to prove that they had never known a case of fatal poisoning due to the use of salicylic acid as a preservative. Unfortunately, it is only the big firms that can manage to bring forward such admirable and learned witnesses, and the smaller firms have to suffer persecution by faddists and others who attempt to obtain the public notice by pretending to be solicitous about the public health. Altogether the prosecution did not have a pleasant time, for the magistrate showed his appreciation of the evidence of one of the witnesses by humorously rallying him about his experiments with kittens, as though any‐one could presume to judge from experiments on brute beasts what would be the effect on human beings—the “lords of creation.” Everyone reading the evidence will be struck by the fact that the defendant stated that he had once tried to brew without preservatives, but with the only result that the entire lot “went bad.” All manufacturers of his own type will sympathise with him, since, of course, there is no practicable way of getting over this trouble except by the use of preservatives; although the above‐mentioned faddists are so unkind as to state that if everything is clean the article will keep. But this must surely be sheer theory, for it cannot be supposed that there can be any manufacturer of this class of article who would be foolish enough to think he could run his business at a profit, and yet go to all the expense of having the returned empties washed out before refilling, and of paying the heavy price asked for the best crude materials, when he has to compete with rival firms, who can use practically anything, and yet turn out an article equal in every way from a selling point of view, and one that will keep sufficiently, by the simple (and cheap) expedient of throwing theory on one side, and by pinning their faith to a preservative which has now received the approval of a magistrate. Manufacturers who use preservatives, whether they are makers of wines or are dairymen, and all similar tradesmen, should join together to protect their interests, for, as they must all admit, “the welfare of the trade” is the chief thing they have to consider, and any other interest must come second, if it is to come in at all. Now is the time for action, for the Commission appointed to inquire into the use of preservatives in foods has not yet given its decision, and there is still time for a properly‐conducted campaign, backed up by those “influential members of the trade” of whom we hear so much, and aided by such far‐reaching and brilliant magisterial decisions, to force these opinions prominently forward, in spite of the prejudice of the public; and to insure to the trades interested the unfettered use of preservatives,—which save “the trade” hundreds of thousands of pounds every year, by enabling the manufacturers to dispense with heavily‐priced apparatus, with extra workmen and with the use of expensive materials,—and which are urgently asked for by the public,—since we all prefer to have our foods drugged than to have them pure.