Evening star. [volume] (Washington, D.C.) 1854-1972, 1931-10-22
BY DIR. KARL ARNSTEIN,

BY DIX. KARL ARNSTElN,
AS Interviewed by r. A. Bruner
copyrighted by the Associated Press. 1897
AKRON, Ohio, october a. The
U. S. S. Akron. accepted yesterday by
the Navy, is an airworthy ship. That
much we know from the test flights
just completed.
When the tests for strength were
made in the dock before the trial
flights, the ship was loaded down with
tons of weight, until it seemed as
though we were deliberately trying to
break its back. In the air it was made
to dive and climb at speeds deemed
dangerous In former practice.
Some 40 men were on duty during
the tests, watching at every section of
the ship for any sign of strain or snap
ping wires or loosening rivets. The ship
met the test magnif1cently.
Naval specifications under which the
ship was built called for 1t to demon
| Strate rate of climb of six meters
a second. That is approximately 1900
feet a minute. The ordinary Office
building elevator ascends at about 240
feet minute, while the Empire state
elevators, the fastest in the world. have
rated speed of 1900 feet-the rate
OF climb prescribed Tor the Akron.
Driven upward at an angle of some
IL degrees, to pressure height and be-
yond, the ship easily made its required
six meters, seven meters, then eight
meters per second and more, the
! structure absorbing pressure from the
distended gas cells greater than any
former ship has taken.
Weight Must Be Saved.
Theoretically an airship could be
quilt as strong as a bridge or concrete
building. But surplus strength can be
built only at the expense of weight.
! And an airship must fly.
| The problem of the Navy and the
Goodyear-Zepp designers was to
build ship which in every particular
| would meet the stresses it might en-
counter in the toughest flight.
The problem of maximum strength
and minimum weight is ever present in
airshtp building. The trick is to effect
a nice balance between the two, then
to check by meticulouS tests, to see how
closely you have hit it-and to resolve
every doubt in favor of strength.
No airship was ever tested out with
such scientific precision, from stem to
stern, top side to keel, the interior of
the ship was literally dotted with
curious gauges and recording instru-
ments, many OF them specially designed
Tor this purpose. Even the seismograph,
used for detecting earthquakes, was
utilized to measure vibration.
The science of aerodynamics is still
new. 1t was unknown when Count
zeppelin built his early ships. Wind
| tunnels have furnished valuable data
but no wind tunnel can compare with
| the supreme proving ground of the air
| itself, with full sized ship, fighting
| It's way through varying air turbulences
| and Gains, gusts and storms.
The eight engines of the Akron.
| thanking the two sides of the ship. are
mounted in line, "A feet apart Even
at that spacing, the rear propellers will
De somewhat affected by the slipstream
OF those forward. How much?
With the propellers of the first and
| third engines turning clockWise, the
second and fourth turning counter
c!ockWise, with graduated pitch of the
blades. our researches indicated a mini
mum of slippage.
We knew that an airship, utilizing
! dynamic forces resultant from its speed
and the angle flown, will carry more
than it can lift by the buoyancy of the
gas alone
more gas cells losing gas badly from ac-
cident or shell holes, or even completely
dedated. have brought their ships
safely in.
Aboard the Akron this dynamic lift
was exactly measured. The ship was
sent to pressure height (the altitude at
which the helium expends until it com
pletely fills the cells), then deliberately
drlven still higher at sharp inclina-
lion 1or stated periods,-valving gas as
IL climbed, making the ship successive
~ two tons heavy, five tons, seven tons
l-leveling off finally at 5000 feet with
load of $4,000 pounds more than it
could hft-then dropping IL tons of
water ballast into Lake Erie to check
the accuracy of the calculations.
We expected to find bugs" in tie
ship. Automobile makers have built
| millions OF cars, but even with this
wealth OF experience, they test a new
| MODEL out for weeks, finding and elirni-
mating bugs" before they market it.
Ihere have been less than 200 air
ships built In the world and the Akron
was nearly twice the size Of the Graf
zeppelin and included features never
| before incorporated in airships. There
have been bugs" in the Akron, but
none OF them serious and fewer than
expected.
Gears Proved Problem.
In any test period one is apt to think
more about the bugs" than the fea-
lures which work. The Maybach mo-
tors again demonstrated their RELIABLE
ity and endurance. The gear makers
had real job. The power the engines
develop has to be transmitted through
an i8-foot shaft, then turned at right
| angles to drive the propellers. Seven
of the eight gears were built in Amer
lea, one in Germany. They have de-
livered power to the propellers with al
most no loss of efficiency.
The airOlaneS the Akron lie m rarrv
inside its hull have not been installed,