RESEARCH FOR AERONAUTICS—FARREN 261 
peller and supercharging arrangements by which the power is main- 
tained up to heights at which the air density is half, or even less than 
half, of that at ground level. 
For the same percentage fuel weight the range is some 40 percent 
better at a much higher cruising speed. Specific fuel consumption 
is much the same in spite of the great improvement in specific per- 
formance achieved in the face of the burden of supercharging. We 
must acknowledge here the tremendous contribution of high-octane 
fuel. 
We are left in both cases with about one-sixth of the total weight 
for the man, his equipment, and armament. The weight of the man 
is the same as it was. In 1918 it exceeded that of his whole fighting 
equipment. Today it is but a fraction of it. The weight of the 
bullets alone in the modern fighter exceeds that of the whole arma- 
ment of the S. E. 5. 
For the bombers, weight analyses are strikingly different from 
those of the fighters (table 3). In 1917 we thought it natural for the 
structure weight of a large bomber to be greater than that of a small 
fighter—40.4 percent compared with 29.7 percent. In fact there was 
a view, widely held and expressed somewhat forcibly by Dr. Lan- 
chester, that aircraft of larger span than say 100 feet would be 
uneconomical because of the operation of the square-cube law char- 
acteristic of geometrically similar structures. Designers, aided by 
research, have managed to avoid the consequences of this law. They 
have been so successful that the structure weight percentage for the 
Lancaster is practically the same as that for the Spitfire. The load 
factor of the bomber is, of course, much lower than that of the fighter. 
But it is probably little different from that of the 1917 bomber. 
The progress that has been made is therefore remarkable. 
TABLE 3 
Handley 
Page 0/400 Lancaster 
Percent Percent 
PUT CUUT Es ae ee eee eres a ree te ek a eh eras St eek See ee 40. 4 31.4 
DEL \ Tere Te} EW a Se eh ea TY NE oe NS SR SE Rs eR ee ee 22.0 16. 4 
CHIL eee eek LN ARACEAE AAT Oe Cea E i ST a eS AAR A 19.3 19.8 
loyal see ee be ae ee ey eee eae oe eee 18.3 32. 4 
PI Cells ake ec eae ee eee at et dans PS LTS yo ad Sh iy 100. 0 100. 0 
In the achievements summarized above I think aerodynamic, struc- 
tural, and power-plant improvements can fairly claim about equal 
shares, and to each, I suggest, the contributions of research and of en- 
gineering skill and ingenuity have been about equal. To pursue the 
analysis would lead me away from my main theme. But I think we 
may, with advantage, examine the history of effort in the structural and 
