Evening star. [volume] (Washington, D.C.) 1854-1972, 1927-01-09

4 n reau OF standards. 1t 1s an
efficient sleuth for the detec-
ton of aircraft that are anywhere
from s to 20 miles away from the point
where the tests are made.
The potential importance of this
discovery is immeasurable at this time,
but it will surely develop into a most
valuable accessory of both military,
naval and commercial aviation. The
detection is made by means of sound
waves, the apparatus which has
been developed for that purpose
being compact and reasonably simple.
Here in brief, popular language
is the way in which the modern de.
| tective of airplane presence works.
| The sound waves from the invisible
and far-away aircraft enter a large
horn and then pass through an ex.
| tensive series of small holes drilled
| in a brass plate. A very sensitive
aluminium diaphragm is placed a short
distance behind this plate. The sound
waves speeding with the marvellous
| IA pidity at which sound travels, even
| tually reach the device and set in
vibration the aluminium diaphragm.
| These vibrations are transformed into
amplified sound waves by electrical
means.
An ordinary set of RADIO ear phones
Is used In increasing the audibility of
these vastly magnified sounds.
This efficient apparatus has been
used successfully in detecting sounds
from an airplane in flight from Is to
| 20 miles away. 1t is a simple matter
to distinguish these particular sounds.
IL the airplane Is in operation only
. to 10 miles from where the detec-
| tor is located, science is able TO
| determine the travel direction of the
cloud cruiser with reasonable &C.
curacy. One outstanding feature Is
the compactness and easy portability
of the 'airplane detective" which
occupies small wooden case con-
tanning the simplifying unit as well
as the batteries.
The laboratories of the Department
| or Commerce, which delve into the
most intricate puzzles of industry. are
productive Of answers to engineering.
industrial, commercial and agricul-
tural problems which never before
| have been studied or solved. The
scope OF the research program an
nually In progress at that establish
ment runs the gamut, from burning
test buildings to ascertain how con-
hagrations occur to solving the Sc
crets Of pipe corrosion. The liveli-
ness and durability of base balls may
/
room. while in another hall of re-
search photographs are being made
of rife bullets In fight or granite
or marble samples are being frozen
and thawed in technical ice chests
to determine their serviceability.
During the last year a curious
study of the vibrations in rife and
gun barrels caused by the explosion
of powder has been under Roadway.
| CO hA t.,
ventor the world has ever known, has
originated a clever little device which
records the amount of these vibra-
tons. Insignificant though they may
appear, these vibrations may result
| in defective craftsmanship either
with big guns or small target rifles.
| These technical tests have demon
strated that the greater muzZle vi
brations occur from the lighter pow
der charges just as the bullet leaves
| the gun. Big and little armament from
the period Of the Civil War up to the
best rife Of current popularity have
been tested by the national gun
, shooters" in these experiments, the
! first of their kind ever attempted.
In the three wind tunnels at the
Bureau of Standards some 20 differ
| ent combinations of aerial bombs have
| latterly been tried out under various
wind speeds. BY making slight modi
fications in the nose and tail forms of
these bombs, the resistance of air
currents and atmospheric pressure to
their fights have been reduced as
much as SIS per cent. Air-resistance
experiments with gas shells have also
been made.
Duralumin, one of the lightest and
strongest materials produced for air.
craft construction-particu in
the building of airplane gtrders-is
being studied from stem to stern IN
order to eliminate defects and add
increased durability to this important
material. The embrittlement of this
material, which Is much lighter than
stone and stronger than steel, Is now
one OF the critical riddles OF aircraft
construction. Protective coatings
which Uncle Sans engineers have
developed have increased the depend
ability and durability of duralumin. .
1t only takes one-half as long now
as it did formerly to make an accu-
rate aerial map of a certain city or
stretch of country as a consequence
of improvements made in the lenses
of regulation mapping cameras by
Standards specialists. Distortion.
which was prominent in the former