Evening star. [volume] (Washington, D.C.) 1854-1972, 1931-01-11
Aviation
BY JOSEPH S. EDdERToN.


First, it is necessary to reduce gen.
orators, transmitters, receivers, an
tennae and other apparatus to light
weight, small volume and minimum in
reference with the planes operating
meters and controls. The apparatus
must be absolutely reliable, as it is
usually out of reach of the pilot, and
repairs during flights are out OF the
question"
Due to the noise on most planes,
he said, mouthpieces of special design
are necessary. In the hand-type MI
| crophone developed for this use the
rubber mouthpiece is held tightly over
the lips and practically all noise Is
excluded from the transmitter. The
closed cavity into which the pilot talks
is so shaped as to avoid distortion OF
speech as much as possible.
Head telephone receivers similar TO
those worn by telephone and radio OPP
orators may be used in airplanes, Mr..
Ryan continued. A more satisfactory
headset has been developed, however,
employing a phonetic type OF receiver
originally developed for the hard-ot-
hearing. These receivers weigh less
than an ounce and are connected With
small ear moldS fitted to the ear OF
the pilot So that the pilot may leave
the plane quickly in case of emergency,
it has been necessary to devise plug
which will provide good electrical con-
tact in spite of heavy vibration and yet
which will pull out at any sudden jerk.
Small Generator Developed.
A type of wind-driven generator to
supply power for both fllament and
plates of the receiver has been devel-
oped which is only inches in diameter
and weighs only seven pounds, complete
with the propeller. To offset electrical
interference from the engine ignition
system, it has been necessary to de-
velop shielding which includes the mag
neto, low-tension magnetic circuits,
high-tension leads and spark plugs. 1t
also becomes necessary to bond cleo
trically all metal parts of the plane to
avoid noises in the receiving equipment
from intermittent electrical contacts
between metal parts. If transmitting
equipment is installed, the bonding also
is necessary to protect against the pos
sibility of high voltages between adj
jacent metal parts producing sparks
which might cause fire.
Two types of radio apparatus now are
in use generally in planes-a long
wave receiver for weather and radio
beacon signals, sent out from Depart
ment of Commerce airways and range
stations on a band between 285 and
$50 kilocycles, and a Short-wave, two
way radiotelephone system for use in
the short-wave bands between 1900 and
5000 kilocycles allocated for this pur-
pose by the Federal Radio Commission.
In Mr.. Ryan's laboratories there has
been developed an airplane radio trans
mitter weighing only 80 pounds, while
the long and short wave receivers
weigh about Is pounds each. In both
receivers remote control is accomplished
by means of small units, within reach
Of the pilot, and the receiving appara-
tus itself may be located as much as
40 feet away
To operate the transmitter and re-
ceiver, the pilot uses a master switch
having three positions In the first po-
sition everything is cut off; in the sec
ond, normal in fight, the receiver picks
I'D messages; in the third the appara-
tus is made ready for transmission and
reception combined. In order to talk
the pilot must press a push-button, To-
Gated in the hand microphone or on the
stick, which starts the transmission ap-
paratus
Foreign Airmail Planned.
This year is going to witness a
marked expansion Of Uncle Sans
foreign airnail service if plans of the
Post ONCE Department work out.
United States mails are carried by
foreign airman lines in South and
Central America and the West Indies.
To this system will be added a trans
atlantic line and the first unit of
line through Canada, which eventually
is to be extended across the Boring
Strait through Soviet Russia to Japan
and China.
Postmaster General Walter F. Brown
now is considering the revised specifi-
cations for transatlantic service by way
of the Azores. Last month bids were
called for this pioneering ocean service,
but the advertisements were withdrawn
about a week before the date set for
the opening because of "ambiguities"
in the specifications.
The redrafted advertisement now is
awaiting only the approval Of the Post
master General before being reiSsued.
Bids are to be opened so days after
the advertisement appears.
The first unit of the great foreign
airnail line through Canada will be
opened February 2 between Minneapo-
lis-St. Paul and Winnipeg, with stops
at Fargo and Grand Forks, N. OAK,
and Pembina, Canada. This line will
form the last link in a system stretch
ing north and south for IL 900 miles,
from Buenos Aires, Argentina, through
| the south temperate zone, the tropics
and the north temperate zone into the
sub-Arctic at Iklavik, Canadian Yukon,
where mails have been carried by dog
team.
Airport Crop Good.
There were few days during the past
six months that did not witness the
completion of an airport or landing
field In some part Of the United States
According to a survey made by officials
| of the AeronauticS Branch, Depart
ment Of Commerce. there were 125 air
ports completed between July IS and
December 81, bringing the total num-
Der in this country to 1882 airports
and landing fields
One Of the startling facts revealed
| by the survey is that Alaska now
has more auxiliary landing fields than
| any CT the States, SO fields of this
| type being credited to the Territory.
! California leads all the States with
165 airports, Texas being second with
| ll9 and Pennsylvania third with "a.
Marine Corps Notes