RESEARCH FOR AERONAUTICS—FARREN 269 
height. At the heights at which it is likely that such speeds will be 
economical, from the power aspect, calculation suggests that rather 
low wing loadings will be required. Figure 8 shows the results of 
some preliminary calculations on this point. The wing loading cor- 
responding to the critical conditions is sensitive both to airfoil thick- 
ness and to height. For example, assuming 60 percent of laminar 
flow, 15-percent thickness, and a camber appropriate to the lift co- 
efficient, the critical wing loading at 35,000 feet is 28 pounds per square 
foot; or for a 16-percent thickness, 20 pounds per square foot. At 
30,000 feet the corresponding loadings are 44 and 35. If these calcula- 
tions are sound, the effect on the general economics of the situation 
will be marked. Here is another reason to justify extensive theoretic 
and experimental work in this field. 
Thus we see both the barriers to progress which now face us and 
the potential rewards that will be ours if we can succeed in surmount- 
ing them. I return to my main theme—the research worker, the 
designer, the constructor, and the user must join forces and, each 
fortified by the confidence and help of the others, plan the work that 
is needed to provide the information, pursue the investigations in 
the conviction that the aim is worthy of the effort demanded, and 
apply the results to produce better airplanes. 
From aerodynamics we demand not merely the bare solution of the 
problem of forms providing laminar flow, relatively immune from 
effects of compressibility. We require specific information covering 
the whole airplane, including its propulsion, stability, and control. 
It may be that the whole lay-out of the aircraft will be different from 
that to which we have been accustomed. It is for the aerodynamic 
people to say, but they must base their opinions on a sound foundation 
of experiment. 
From structural research we require to know what schemes of 
structural design are most likely to provide the necessary precision 
of form and superficial smoothness and how to cope with new strength 
and stiffness requirements. Aerodynamics must supply information 
on the loads that will be met in flight, and much thought must be given 
to the meteorologic conditions that will be encountered. 
In the future it will be impossible to consider the airplane engine 
and the airplane as separate enterprises with conflicting requirements. 
The thermodynamic problems will be aerodynamic also. Their joint 
solution will throw up more than enough of the design problems at 
which the power-plant engineer excels. 
Will the transformation of the energy of the fuel into thrust de- 
mand a propeller or a jet or a combination? There is no single 
answer. It will depend on the duty of the airplane. But the propeller 
designer will find that his task will tax all his ingenuity. 
