FIFTY YEARS OF FLYESTG PROGRESS — LOENING 207 



stead of facing the problem of efficient lift and how it could best be 

 obtained, aviators and constructors, from the very start to well into 

 the 1930's, got themselves wound up in so much argument as to the rela- 

 tive merit of biplanes and monoplanes that it took no less than 40 years 

 to clear up what was very obvious from the beginning. The reason 

 the Wrights went to the biplane was perfectly sound and had to do 

 with the question of bracing, weight limitations, and a good deal of 

 engineering convenience. But with the development of higher speeds 

 and more power, the reason for the biplane vanished. But the biplane 

 did not ! And throughout the era from 1918 to over a score of years 

 thereafter, the biplane form of wing structure stubbornly persisted. 

 Finally, however, this gave way to the situation we have today — no 

 biplanes in the air in the world except a few old-time crates towing 

 advertising banners ! The author derives a very distinct gratification 

 from this because in 1918 he was convinced of the correctness of the 

 monoplane type, but was almost alone in this country in advocating it. 

 He found the acceptance of the monoplane by the aircraft industry's 

 customers so difficult and so surrounded with prejudice that in 1923 

 he was forced to make the Loening amphibian a biplane for no other 

 reason than to sell it. The greater lift of the monoplane owing to the 

 lack of interference of one wing with another, the considerably lower 

 head resistance, and the lighter weight, won out in the end over the 

 fancied objections that had been harped upon for so long. The unten- 

 able antimonoplane sales talk was that a monoplane was unstable, 

 structurally weak, and too "tricky" in maneuvers. The simplicity of 

 the monoplane structure insured its survival — particularly of the type, 

 referred to above, with a simple strut bracing, which type 20 years 

 later came into very general usage and still is seen in the Cessnas, Cubs, 

 Beavers, and others. Of course, eventually the struts have been super- 

 seded by the cantilever monoplane structure that is now so nearly uni- 

 versal. A quotation is given here from a treatise on this subject by 

 the author, "Revival of the Monoplane," written in 1919, which per- 

 haps has a message to give : 



Aeroplane designing is merely a series of extraordinary compromises that have 

 to be hit upon with a rare judgment because in general all aeroplane features 

 fight each other — weight needed for strength reduces flying performances, roomi- 

 ness for convenience requires a sacrifice to head resistance, etc., so that the com- 

 petent engineer must constantly balance these opposing features. If he brings 

 out a triplane, let us say, just for the sake of making it a triplane because other 

 machines are biplanes, without having very clear and logical reasons for doing 

 so, he fails in his true mission. The ideal features that we are looking for in 

 the aeroplane structure itself are (1) light weight — the most important of all — 

 (2) the combination on a machine of stability (meaning ability of the plane to 

 stay where it is put along its course), combined with easy controllability (which 

 means a quick, positive response to all controls) — this is perhaps the hardest 

 feature to develop in a new plane; (3) the desirability of simplicity of construe- 



