Smyrna times., 1928-12-26
FIELD ILLUMINATED
BY AIRPLANE'S HUM
Ingenious Electric Device
That Aids Night Flying

Pittsburgh PA formidable en-
emy of night fying-the unillumt-
mated landing field-was conquered
automatically by the modern wizardy
of electricity at Bettis field, McKees-
port. the other night. At a public
demonstration there the hum of a
plane, one thousand feet in the air,
closed switch on the landing field.
A bank Of airport floodlights was
turned on, and an instant later the
pilot was gliding safely along path
Of illumination that was called into
being by the voice of his own plane.
Thousands witnessed the successful
exhibition of the sOund-sensitive au-
tomato lighting agency developed by
i. SpoOner, research engineer of the
Westinghouse Electric and Manufac
turing company.
Merle Moltrup, chief of the air mail
pilots at Belts field, made the land
ing which opens new volume in the
annals Of aviation.
Essentially the function of the de-
vice is to use the drone of an air
plane to control electrical energy. At
first this controlled energy is a tiny
weakling, but it is nursed along by
a corps of amplifers. and finally
emerges as a husky child capable of
closing a goOd-siZed lighting switch.
This switch locks automatically and
the lights remain on until turned off
by the field attendant
Loud Speaker Reversed.
A loud speaker constitutes the 'ear"
of the mechanism. 1t works in re-
verse order, inhaling rather than eX-
haling sound The loud speaker laid
on its back gives the apparatus a di-
rective effect with reference to noises
from above. micrOphone completes
the auditory section. After passing
through the initial amplifier the i'm
pulse is received by a resonant cir
cult set, tuned to the dominant fire.
queacy of the airplane drone. Here
a second amplifier does its work and
then the thread is picked up by a
device which has an amplifying power
Of 1OOOOO,OOO.
The electrical impulse, which a
split second before was awakened by
the hum Of the plane, is now ready
for the time-limit relay-the last step
III the process before the long arm of
electricity reaches out to close the
power switch
The time-limit relay is a vital unit
in the Spooner sound-selective switch.
Without this feature the automatic
lighting mechanism might be operated
BY sporadic transient noises With
The time-limit feature nothing less
than the continuous hum, character
istic Of the moving plane. will op-
crate the apparatus and light the
field. Lacking this unit the appara-
tus would be like a nerve frazzled
watchman. who, startled by the
slightest disturbance. jumps to the
lighting switch. not knowing whether
the noise he heard came from the
air or the earth The time-limit
agency gives the Spooner device the
advantage Of the self-possessed watch
man who knows what he is about to
DO before he acts.
New Type of Protector.
The lights that went into action
automatically came from a new type
OF airport protector developed by the
Westinghouse company.
The new unit is designed to fur
nish sufficient illumination over an
uneven field, at the same time keep
ing the source of light low and elimi-
mating Objectionable glare in the eyes
Of the aviator 1t consists essentially
OF steel drum 25 inches In diameter
and 10 inches deep. mounted on a 2115
inch pipe standard. Mounted within
the drum are lamp socket with YER
tical, lateral and in-and-out focusing
adjustments, % : inch parabolic
metal reflector of such focal length
that all reflected rays come approx
mately within degree diverg-
ence, and a system of lowers to alb
sorb all those rays of direct light
the upward tilt Of which exceeds ~
degrees. A spread lens mounted in
front OF the shell gives a horizontal
spread Of As degrees to the beam.
The unit is so mounted on the pipe
standard that 1t may be rotated hori-
zontally, or tilted vertically two de-
grees above and six degrees below
the horizontal 1t is dust and rain
proof.
When equipped with a 1,J0O-watt
projection lamp and spread lens. the
unit gives maximum intensity of
250,000 G. r.. with an estimated in
tensity with plain lens of 100000
G. r. The protector may be accu-
rately focused by the use of a day
light lamp-setter developed for the
purpose.