DISCOVERY 



Latest Developments in 

 Aeroplanes 



By "Rafcx" 



Altuoi'GH perhaps it is not very apparent to the pubUc, 

 there has been a good deal of progress in aeroplane 

 design during the latter part of the three years which 

 have elajised since the Armistice. It is proposed in 

 this article to deal chiefly with the evolution of commer- 

 cial machines ; mainly because it is this type which is of 

 more immediate importance, but also because the de- 

 velopment which has taken place in military aircraft is of 

 less universal interest and consists, generally speaking, 

 in a change in the details of war ideas but not a great 

 change in those ideas themselves. Commercial air- 

 craft, on the other hand, did not exist until after the 

 war, and therefore any types which have been since 

 evolved are necessarily novel. It is interesting, there- 

 fore, to watch the general trend of ideas, particularly in 

 \'iew of the gradual departure from the overshadowing 

 military element which predominated even in machines 

 produced for civil use for some time after the cessation 

 oi hostilities. 



Some 01 us, indeed, hold the view that, despite theenor- 

 mousincrease in aeronautical knowledge which was made 

 possible by the War, the development of civil aeroplanes 

 was actually to some extent retarded rather than im- 

 proved by that military effort. This was for two 

 reasons which are more or less connected. In the first 

 place, in military parlance the word "performance" 

 came to have a very definite meaning, implying the 

 sum of an aeroplane's capabilities in rate of climb, 

 " ceiling " (maximum height attainable), speed and 

 mancEUvreability — which are set down roughly in the 

 order of their importance for fighting purposes. Now, 

 it is not difficult to understand that the effect of their 

 importance in war was to stamp those characteristics 

 of an aeroplane firmly on the mentality of the designer 

 and pilot, with the result that the earlier commercial 

 aeroplanes showed clearly that these four points had 

 all been treated as still of great importance. The very 

 advertisements of these first types, as they appeared in 

 the aeronautical Press, showed this obsession. 



The second effect of the predominance of militan- lines 

 of thought arises out of this craving for high ' ' per- 

 formance." To obtain these particular characteristics 

 it was necessary" to fit wings of such a shape in section 

 that they would produce high speed and rapid rate of 

 climb, their capacity for weight-canying per square 

 foot of area being of secondan>' importance. Above all 

 it was necessary to have verj' high engine-power ; and, 

 therefore, the aeroplane in 1918 had almost become in 

 fact what was once stated l)y one of our foremost pilots 



to b<' the desideratum of the lighting airman, the 

 " largest possible engine with the smallest possible 

 fringe of aeroplane round it." 



But it has at last lx;cn recognised that the important 

 characteristics for commercial work are not only quite 

 other than those expressed by the word " performance " 

 in military' aeroplanes, but are even to some extent 

 actively opposed to them, in the sense that the two sets 

 of attributes could not be produced in the same design. 

 Only one of the four militar\' points is of equal imf>ort- 

 ance in a commercial aeroplane, and that is speed ; and 

 even here it is generally true to say that a machine 

 which is capable of maintaining an average speed of 

 100 miles an hour over the ground in all conditions of 

 wind and weather — which implies a maximum speed 

 of about 130 miles per hour — possesses a sufficient 

 advantage over other methods of locomotion ; par- 

 ticularlv when the additional gain arising from the 

 aeroplane's ability to follow a direct route regardless of 

 the physical configurations of the ground below is taken 

 into account. The three other military attributes 

 mentioned above are not necessarj- ; a very high 

 " ceiling " is not a necessity in peace, because most 

 touring is done at a height of 4,000 or 5,000 feet, and a 

 maximum height of 20,000 feet is as much as can conceiv- 

 ably be required, while 15,000 feet is probably the 

 greatest height to which the average commercial 

 machine is ever likely to attain. Again, rate of climb 

 becomes of verj- minor importance. For fighting work 

 it was of course necessary' for a machine to climb rapidly 

 in order to get above an adversar\' — the upper berth 

 being equivalent to the weather-gauge in a naval battle 

 — but in the ordinar^' business of carrying goods or 

 passengers from one place to another it is not of great 

 importance whether fifteen minutes or half an hour is 

 occupied, for instance, in climbing to a height of 10,000 

 feet. It is of course desirable to have a certain reserve 

 of engine-power at starting in order that obstacles close 

 round the aerodrome may be cleared with an ample 

 margin of safetv, but, beyond this, rapidity of climb is 

 not vital. 



Manceuvreability, again, is essentially a military- 

 qualification, for a pilot must be able to change his posi- 

 tion rapidly to avoid enemy fire and when jockeying for 

 position ; but the peace-time carrier of merchandise 

 has no need for these rapid changes of attitude. This 

 attribute of manceuvreability is. in fact, directly opposed 

 to the commercial requirement of steadiness as, generally 

 speaking, and within limits, the greater the " liveliness " 

 a machine possesses from the pilot's point of view, the 

 less will be its quality of automatic stability and freedom 

 from motion in rough weather. 



It will thus be seen that, compared with the militar\- 

 aeroplane, the requirements for a commercial machine 

 are moderate sf>eed, weight-earning capacity, automatic 



