ON AERONAUTICAL PROBLEMS. 403 
way to gain speed is to reduce the resistance of the aeroplane to motion 
through the air. But this is now, in the main, a question of ‘clean 
design ’,—that is, of eliminating all excrescences which needlessly add to 
the resistance of the body ; for we know enough of the principles which 
govern the design of wings, as they are made to-day, to be fairly certain 
that we are not paying an excessive price now for a given lifting power. 
A Case for Competition. 
13. Hence, as it seems to me, the high-speed aeroplane is, as the 
helicopter is not, a suitable subject for prize competitions: year by year, 
the best designing firms in the country should be induced to bring all 
their knowledge and experience to bear on this problem of clean design. 
And so far as we possibly can, we should remove every restriction which 
makes their problem more difficult: the designer should not be able to 
complain, as he complains at present, that when he has built an aeroplane 
of clean design, and is counting on something striking from its speed trials, 
suddenly a host of experts descends upon the helpless craft, and bedecks 
it with armament, wireless, and other ‘ gadgets’, until, as he says, it 
makes its first ascent ‘ looking like a flying Christmas tree’. If you want 
to discover the limits of possibility in the way of high speed, then you 
should go for high speed, as they say, ‘bald-headed’. Obviously, an 
aeroplane on service will have to sacrifice some of its otherwise attainable 
speed to the needs of armament and wireless; but that is no reason for 
making these sacrifices in your experimental machine,—rather, the 
reverse. The principle, fundamental to all physical enquiry, of isolating 
the different factors of a problem, is one of the hardest lessons to drive 
home in connection with development work. 
High Speed and Civil Aviation*. 
[14. Before we pass from the consideration of high speed, I should 
like to make one general observation. Military requirements ought 
always to be recognised for what they are,—counsels of necessity, leading 
in general to the evolution of types which, except under conditions of the 
most intense specialization, could not possibly survive. (What con- 
ceivable use, except for purposes of war, could be made of the ancient 
triereme, of the modern battleship, or of the still more modern ‘ tank’ ? 
Like the warriors of certain savage tribes, they are good for killing, but 
for nothing else.) Especially after a spell of intense development under 
the stimulus of war, we ought to take care that an abnormal standard of 
values is not unthinkingly retained, as though it had a fundamental and 
permanent significance. 
I think that this critical attitude has at times been rather lacking in 
what we somewhat optimistically term ‘the period of reconstruction ’. 
And I fancy that, had it been more in evidence, we might have seen less 
emphasis laid on speed as a dominating factor in civil aviation. Of course, 
aviation has in speed an advantage over other forms of transport which it 
aust be careful to retain; but until commercial flying becomes a real 
actor in every-day life,—so long as the problem set you by the ordinary 
1an is not so much to impress him with what has been done in the air, 
* For want of time, § 14 of the Discourse was not delivered. 
DD2 
