oo ANNUAL REPORT SMITHSONIAN INSTITUTION, 1959 
SEAPLANES 
Our seaplane problem largely involved engine and propeller lo- 
cation troubles. Engines were placed in hulls, overhead, behind, and 
of course outboard on the wings as well as in tractor configurations. 
A cumbersome configuration of inefficient design was the Dornier 
DOX, which was built only once. Present-day jet engines have a 
much wider choice of location because of their light weight and be- 
cause there is no propeller-clearance requirement. 
MATERIALS OF CONSTRUCTION 
Materials of construction of aircraft have gone through many cycles. 
Starting with wood, fabric covering, and wire or cable bracing, there 
soon arose (with Fokker and Esnault-Pelterie in Europe and Sturte- 
vant in America) a trend to metal-frame construction, either struc- 
tural sections or steel tubing, brazed or welded. For several years 
after the war, and in spite of the Zeppelin Duralumin development, 
aluminum was suspect as a structural material—so much so that the 
famous Specification 100-A of the Navy prohibited the use of alu- 
minum in any structural part of aircraft. This is a pertinent example 
of how too-rigid specifications, based on what was good practice in 
previous years, can prevent future development. 
Today we face a similar situation in prohibitions against Fiberglas 
or plastic-stressed structures because it is so difficult, theoretically, to 
calculate and check the stressed condition. Yet plastics may well have 
as great a future in aircraft structures as dural stressed-skin mono- 
coques and wing panels had 30 years ago. We hardly need to re- 
capitulate how metal took over from wood, replacing a material that 
could not stand the weathering difficulties of day-in, day-out air op- 
eration. New alloys—titanium and others—are beckoning alluringly, 
like Fiberglas, for a chance to show their worth. Also, “sandwich” 
materials are most promising. Will we still be slow to accept new 
developments ? 
WHY THESE DELAYS? 
What is the reason for these long delays in acceptance? ‘The lesson 
one seems to gather from the instances cited and many others is that 
aviators’ likes and dislikes have been given too much weight, thus 
discouraging the engineers from perfecting their developments. In 
retrospect, one finds many instances where worthy developments were 
ignored or abandoned. Many a wing flutter that scared a test pilot 
condemned to utter oblivion an airplane that had structural or con- 
figuration features of great importance and advantage. Had the 
customer and the builder been patient or wise enough to work out 
such “bugs,” success would often have followed. 
