The Washington herald., 1912-06-14

A parallel truss is no stronger than its
bending moment, and the result was, as
has been pointed out inevitable. To
build an aeroplane trussed in this man
ner with sufficient factor Of safety
would be a physical impossibility, for It's
weight would be necessarily prohibitive.
Furthermore, it's size would be limited, as
a point would soon be reached when
such a truss would not sustain its own
weight.
Must BE Stable.
The successful aeroplane must be a
machine that can be built to any size
and carrying capacity. 1t must be per
fectly stable under any and all weather
conditions and absolutely automatic in its
balancing action without the aid OF any
so-called equilibrium devices, which act
II they act at all, after equilibrium In its
effected. In short. II must be a utility
machine, not a toy to be operated only
under ideal weather conditions by an ex-
pert operator. Such a machine is neither
a commercial possibility nor can any
great dependence be placed on its use
in warfare.
It has been shown that the size and
weight-sustaining power of the parallel
plane machine is limited Another un-
fortunate feature presents itself. The
planes being perfectly parallel, l. E.. the
distance between the two being the same
from tip 10 tip, there is but a single
point OF suspension, which is in a con-
slant state OF unrest. This Is due to the
fact that there is no definite direction
Of flow of the air cushion under the ma
chine. The planes being level. the air
is constantly trying to get relief in any
direction Of least resistance. OF course,
the trend OF the escaping air Is from
front to back, but II is a fact that can
be proven by experiment that all the air
does not go that way; hence the unrest
which the Intelligence Of the operator
must constantly combat. He must not
only have skill, but also plenty of sea
room" To ride on an even keel, the
point Of suspension must be exactly in
the center, and to keep it there is we'll
nigh impossible, even for the most ex-
pert.
Present Machines Uncertain.
1t is very obvious from the forego-
ing that the parallel plane machine is
remiss in practically every requirement,
and we must look further for the So
luton Of the problem. This brings US
to a form Of construction that is ideal in
every way-the cantilever principle, one
that is constantly used in bridge and
building constructions where great
ing this principle to the bipiane; we get
a double dihedral inverted angle form Of
construction that corrects all Of the
aforementioned faults of the parallel
plane machine
First-It can be built to any size, re-
tanning its stiffness, and the greater the
load applied to the center the sitter It
becomes. Also any. stress applied at the
tip Of the planes only serves to further
stiffen them at the center, for theyi
would have to straighten out fat and
become parallel before they could COL /
lapse there. - ------- .---
Second-There will be three points OF
suspension instead Of one, and these
points do not shift under any circum-
stances whatever. but retain the position
under all conditions. A. diagram here
Will give the reader an idea OF how this
is accomplished. the three points OF sus-
pension being represented by A. b c.