Evening star. [volume] (Washington, D.C.) 1854-1972, 1931-01-18

aviator who earnestly desires 10 lanC
through dense fog.
Echoes are tanned and made to yielc
their benefits to aviators through a de-
vice known as the sonic altimeter.
Developed by the Army Air Corps anc
engineers of the General Electric lab
oratories, the new altimeter automatic
ally ascertains the altitude of the plane
in which it is mounted by measuring
the length of time required for the
sound of whistle blast to travel from
plane to ground and its echo to trave
back from ground to plane.
The principle of the sonic altimetel
Is not new. The Navy has been using
such a device for some time for deep
sea soundings. The measuring of the
time of travel of sound through the sea
water and its echo off the sea bottom
has enabled scientists to chart the
depths of the seas.
The aircraft version of the old Deep
sea depth finder consists roughly OF a
pressure tank, whistle attached to the
tank, a transmitting and receiving
megaphone Joined by a tube, dial
measuring the altitude in feet and a
stethoscope fitted to the pilots ears.
The device is used in somewhat the
following manner:
footing for Altitude.
The pilot toots the whistle The
sound is magnif1ed by the transmitting
megaphone, pointed toward the ground.
The sound reaches the ground and is
transformed into an echo of useful
proportions. The echo clambering back
into the skies to seek it's parent whistle,
is caught by the receiving funnel.
When the plane is above so feet from
the ground the dial automatically reg
listers the altitude through some scien-
tific procedure, too complicated for easy
description. When the plane is below
SO feet the time elapsed between the
blast and the clambering echo is so
short that the dial cannot function.
Here enters the stethoscope, which is
connected to the tube joining the two
megaphoneS. The stethoscope enables
the pilot to hear the blast of the
whistle as the sound leaves the plane
and the return of the echo and to dis
tinguish a difference at any altitude
above feet. Between four and five
feet the whistle and echo tones blend
into one glorious whole and the pilot
knows it is high time. to level off for a
landing.
Another advantage Of the arrange
ment is that the pilot can judge to
some extent the nature of the terrain
below by the character of the echo. An
echo which comes back all fury around
the edges probably has been playing
around in the woods. A nice crisp,
clear echo denotes clear ground below.
For test purposes the sonic altimeter
has been mounted on several planes.
Further work IS to be undertaken to
simplify the apparatus and reduce its
weight.
Used in connection with radio bea-
cons and runway localizing beams,
which the pilot may follow to his des-
tination, the device is intended to be
one of the last links required in the
battle to defeat fog, the airman's worst
enemy.
To Increase Schedules.
What has been termed "air trans
ports boldest experiment" the Inaugural
ton of hourly air passenger service by
trimotored planes between the Ma
tional Capital and New York, Is prov
ing so successful that by next Spring
there may be a tremendous increase in
frequency of schedules, Inauguration of
night service up to midnight and even
further reduction in fares, now below
railroad rates for the round trip.
This was announced by Vernon r.
Lucas, veteran pilot and aviation radio
eApeIt, anu RAJ 1d1I, UOIl uOW COu-
nected with the New York, Philadel-
ton, operators of the hourly service, in
speeches before the Aero Club of Wash
ington during the past week.
There has been no air transport ven
ture in the past two years which was
greeted with more open scof1ng or
forecasts of failure than the hourly
service of 'Nypwac," or the Ludington
Line, as the service is variously known.
In the four months since the service
was inaugurated, however, it has
been so successful that a reduction
of passenger fares has been possible,
and still further reduction is expected.
It is claimed that every passenger rec
ord on any airline in the world has
been broken on the run between this
city and New York. Despite long pc
RODS of fog and thick weather, the line
has maintained 81 per cent service
since its Inauguration.
Lucas talk before the Aero Club was
q delightfully."- frank discussion OF the
air transport business, based on his ex-
perience with several of the largest lines
in the country.
Practically all early air transport or
ganization was undertaken without any
effort having been made to ascertain
costs, Lucas said. No one knew what
the outcome would be, and the results
showed that in many cases, without
Federal support. there would be no pos
sibility of profit.
with the possible exception of Earl
Sideways Line now abb
sorbed as part Of the new Southern
SYSTEM. Lucas said,
''there was no line in the past that
could possibly pay its operating ex-
penses out of passenger revenues"
Watres Bill Criticized.
The new Watres airmail bill, passed
by Congress last year as an aid to
air passenger lines, has been admins
tered with some results which at nrst
glance appear almost ridiculous, Lucas
declared He said that he has seen
big tri-motored plane weighing $500
pounds empty. with one or two paSsen-
gers aboard, taking on mail.
There would be l pound ounces
for one stop, IL ounces for another, and
so on" Lucas said. You could carry
the entire mail load under one arm.
For each pound of this mail kindly
Uncle Sam was paying 40 cents per
mile, plus IS cents for the tri-motored
equipment, plus cents for two-Way
radio equipment"
Most Of the earlier air transport ven
lures were loaded down with deadwood,
Lucas said They supported 'prima
donnas" in the form of nephews and
cousins and other relatives OF the
president. the vice presidents and others
down the line. all of which chewed up
ssvenues. On top of this they struggled
20 make out with planes costing $l.25
per mile to operate. The result was
they had to charge rates SO high that
40 one but the wealthy could afford TO
g.. If they reduced rates to point
where passengers began TO come, they
could not pay operating expenses, and
the more passengers they carried the
more money they lost.
In establishing the "Nypwac" Line.
Paul Collins and Eugene Vldal, VINO
have worked UP the operations program
based upon years of previous airmail
and air-transport experience, decided
49, a. ornratiors methods in common