Evening star. [volume] (Washington, D.C.) 1854-1972, 1922-02-24
BLAME zR-2 WRECK
ON0vERSTRESS|NG
Structural Weakness Led to
BuckIing of Girders,
Probers Believe.
PLANS CAREFULLY DRAWN
Methods of Calculating Considered
Sufficiently Accurate in En-
gineering Practice.
PLANS CAREFULLY DRAWN
By the Associated Press,

D! tne Associated Press.
LONDON, February 23.-The buc-
King of certain girders amidships of
the dirigible R-3s-lated named the
ZR-2-on her third trial was sig
nihcant as being the first Indication
OF the existence of dangerous stresses,
Is the opinion to which the aeronau-
tlcai research committee incline in
reporting that the accident to the
olris1ble on August "a. last. when she
met with disaster with great loss of
life at Hull. was due to structural
weakness. The report further shows
mat the committee is of the opinion
that the action of the late Flight
Lieut. Pritchard in steadying the ship
and relieving the stresses saved the
dirigible on that flight.
1t Is recalled among the London
leaders or the committees report that
the Observer ON August 81. last.
when the R-3S was .unexplainably
delaying it's final trial at Howden, de-
CARED that there were defects in the
ship which had been kept secret for
from four to five weeks.
On August 20, Brig Gen. Maitland,
then of the air ministry, said to the
corresondent of the Associated Press
at Howden: "You know, all sorts of
stories and rumors are being spread
as to why we are refusing to take
chances, but 1 wish You would say
that it is the weather, and the
weather alone. that is delaying mat
ters."
insufficient Strength Margin.
The aeronautical research commit
tees report says that apparently it
has been clearly established that the
R-3S had an insufficient margin of
strength to Withstand either normal
due to bad weather; it declares that
the weather at the time did not con-
tribute to the accident
Other conclusions of the committee
include that during her final flight
the R-3S was not excessively loaded
for normal navigation; that she was
considerably weaker than previous
British rigid ships; that the provision
of special powerful control surfaces
of new design accentuated this
weakness. and that in the design NJ
calculations were made of stresses
due to the aero-dynamic forces to
which the ship would be subjected.
Consequently, the calculations by
the design staff, taking specific ac-
count only of forces and movements
due to the distribution of weight and
buoyancy, including gas pressure.
We're misleading. From evidence of
the behavior of the ship in the last
hour preceding the accident, con-
tinues the report, lit is not impos-
sible that the process of failure was
gradual and that the final breakage
was the cumulative effect of a num-
Der of reverSes of stress, falling not
far short in magnitude of an actual
failing stress"
The committee concluded that the
existing methods at present used in
determining the scantlings of the
structural members of the airship
We're inaccurate for the purpose, and
declared that the terms of the re-
quirements laid down at the time of
the war for the R-3S were drastic
and imposed too severe a task on
the designers, and that faulty ma
terial did not contribute to the &C
cident. The structure, it asserts, was
designed with great skill and the
necessary calculations were care
fully executed by methods admitted
to be sufficiently accurate in other
branches of engineering practice.
According to the report, the de-
sign staff considered the aerody-
mamie stresses to be less important