Activate Javascript or update your browser for the full Digital Library experience.
Previous Page
OCR
ee A
Saeed
EDA O98 OES petits <t
Laan
i
x
peer a a een tense nS Stn
;
k
THE OWL
EXCHANGES
(Continued from Page Fourteen)
tive lens, halfway toward the handle a con-
densing lens, and between these two a dia-
phram, or small slide, with the arrow on it.
A lead which can be plugged into any con-
venient outlet is attached to the handle. A
125-watt lamp is used to obtain the intense
light necessary, for the arrow can be seen
even when projected against the white of the
slide. A small switch on the handle of the
pointer turns on the arrow, and a push but-
ton informs the operator of the projector
when the slides are to be changed. Thanks
to the electric pointer, the lecturer can see
his own slides from a suitable distance.”
PILOTS TUNE ENGINE BY EYE
An ear for music isn’t going to be one of
the requirements for pilots of multi-motored
planes any more.
By a new discovery, description of which
was recently sent to the Department of Com-
merce, pilots are able to tune their engines
into perfect synchronization by eye.
Like the tricks on a magician’s stage,
“it’s all done with mirrors.”
Faulty engine synchronization is what
makes that flailing ‘whoo-whoo-whoo” so
disturbing to passengers and so expensive to
airline operators because of deterioration by
vibration.
Engines can be fairly well synchronized
mechanically but the final tuning always has
had to be done by ear. A tone deaf person,
just couldn’t accomplish this tuning at all.
Chance Discovery
It seemed like just one of those things un-
til George Kraigher, chief pilot of the west-
ern division of Pan-American Airways,
walked out in front of a tri-motored plane
a couple of months ago to make a final in-
spection before the takeoff. He noticed that
across the disc formed by each whirling pro-
peller there was a bar of light, and that
these bars were at different angles.
He experimented by speeding up or slow-
ing down one engine after another and
found that the bar moved with varying
speed. And when the speed of each engine
was made such that the bars were parallel
all engines were running at exactly the same
rate and the “‘whoo-whoo-whoo” was entirely
gone.
That was all right so far, but a man can’t
pilot a plane while standing out in front
of it, nor can he look through the wing pro-
pellers while sitting in the cockpit. So
Kraigher arranged a series of mirrors to
carry the bars of light on the side propellers
right up next to the one on the center mirror.
Kraigher’s discovery was considered so
important it was decided not to patent it
but to present it to the industry, and so full
description of the instrument was sent to the
Department of Commerce for general dis-
THE OWL
NEEDS YOUR SUPPORT
DON'T FAIL US
tribution.
ORDER YOUR
1933 BELLE AIR
NOW
sixteen