256 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1944 
change. I think, however, that we shall see that the effort to preserve 
them unchanged has made as high a demand on research and engi- 
neering skill as that required to produce the more obvious improve- 
ments. 
During the last war the Royal Aircraft Factory (which became the 
Royal Aircraft Establishment in April 1918) produced many designs 
for aircraft which were constructed in large numbers. One of the most 
successful was the S. E. 5, a single-seat fighter with a 180-hp. Hispano 
Suiza engine. It had a creditable history as a fighter. I propose 
to compare it with a Spitfire. Then I shall take the Handley Page 
0/400 twin-engined heavy bomber and compare it with a Lancaster. 
I shall not be giving away any information to our enemies. They 
are well acquainted, in more ways than one, with both Spitfires and 
Lancasters. Some of them may even remember the S. E. 5 and the 
0/400. For my purpose it is quite sufficient to take examples of marks 
of the modern types whose performance has long been surpassed. 
Let us first look at them in general outline. Figure 1 shows the 
1917 fighter. In Figure 2 its specifically military features have dis- 
appeared and around it is the outline of the Schneider Trophy 
streamlined monoplane, the essential product of the period between 
the two world wars. Figure 3 shows the 1942 fighter. In Figures 
4, 5, and 6 is shown the transition from the 1917 bomber, through the 
streamlined airliner, to the 1942 bomber. The most obvious differ- 
ences are the change from biplane to monoplane and the general 
cleaning-up due to enclosing the crew, abolishing external wing 
bracing, and retracting the undercarriage. Comparing them type 
by type, the over-all dimensions are not very different. The Spitfire 
has the same wing surface as the S.E.5, about half the drag, nearly 
twice the strength, three times the speed, four times the total weight, 
four times the military load, and seven times the power. The Lan- 
caster has about half the drag of the Handley Page 0/400 on the same 
span of wings and about three-quarters the wing surface. Its total 
weight is nearly five times as great; the wing loading, over six times; 
the power, seven times; and the military load, with a 25 percent 
greater range, over eight times. Let us inquire how some of these 
improvements have been made. 
DRAG REDUCTION 
The change in drag coefficient Cp, is of first interest. I have not 
found it possible to get accurate figures for the older aircraft, but 
they are approximately 0.039 for the fighter and 0.046 for the bomber. 
The corresponding modern figures are 0.022 for the Spitfire and 0.030 
for the Lancaster. Thus, per square foot of wing surface, the total 
drag has been reduced to about 55 and 65 percent of the 1917 standard. 
