Evening star., 1932-01-31

into Iowa and South Dakota and
6.
late In the year commanding officer of
that post and commandant of the Air
Corps Tactical School, then located
there. After two years in command of
the tactical school, he became student
in that school (in such manner are
armies operated) and graduated in
1927. He then went to the Command
and General Staff School at Fort
LeavenWorth as a student and, upon
graduating in 1923, became a member
of the faculty there.
A year ago Gen. WeStover was pro-
NOTED to the permanent Army rank
of lieutenant colonel In addition to
the four aeronautical ratings he holds
Che is one of the few men in the Air
Corps to hold all four ratingS) Gen.
Service Medal for meritorious wartime
service.
Radio Study at Home.
Officers of the local Naval Reserve
Aviation Squadron, which trains at the
Anacostia Naval Air Station, are tax
ing course in radio code in their own
homes It was found to be SO difficult
code drills for the Reserve officers that
the local Reserve division decided to
build small individual short-wave re-
ceiving sets, which are to be issued to
division pilots and used by them in their
homes until all officers have been put
through a full course.
The division completed scheduled
training in navigation, with radio COM
munication, for the current fiscal year
last month. All pilots of the division
averaged Is hours flying time in dead
reckoning aerial navigation problems
and tWo-Way aerial radio communica-
tionS.
Propeller Warning Issued.
Warming to Uncle Sans flying sailors
to take no chances with faulty propel-
lers is sounded in the latest bulletin
Of the Navy Bureau of Aeronautics
Because the modern airplane propeller
seldom causes trouble is no indication
that it can be taken for granted at all
times as completely dependable, without
regular inspection and attention, 1t
was pointed out.
Some idea of the necessity for proper
care in design, test and maintenance of
a propeller may be obtained from the
fact that the centrifugal force alone
acting at the shear shoulders Of To-
foot propeller blade rotating at 1000
revolutions per minute is approximately
100000 pounds" it was stated ITO this
force is added the bending and torque
loads, which are vibratory in nature
and thereby further complicate matters"
1t is because of the tremendous forces
acting in and on an airplane propeller
hub that difficulty has been encoun-
in off ~ iab 10
pitch propeller, though such a pro-
peller long has been recognized as one
of the great needs of aviation.
The problems involved in developing
the controllable pitch propeller are
being given serious consideration by the
best propeller talent in the country, it
was pointed out. Several fairly effec-
tive designs have been put into opera
tion, but as yet there is no controllable
pitch propeller design accepted for gen.
eral use.
Tests at the Anacostia Naval Air Sta
ton have covered variety Of the prin-
Ciples involved in some of the more re-
cent controllable pitch propellers
Various Methods Employed.
One of the controllable propellers
upon which the flight test section at
Anacostia is working utiliZes the bal
ance between the thrust on the blades
and series of heavy springs in the
hub to give automatic control. Another
is controlled by the pressure of oil in
cylinder, fed through the crank shaft.
Still another employs a small electric
motor in the hub, working through a
long train of gears to rotate the blades.
In these developments of the con-
trollable pitch propeller" it was stated,
"the ingenuity and ability of the engi-
neers is particularly well Illustrated by
the fact that equipment which will soon
be serviceable is being produced at
surprisingly small increase over the
weight of our regular service propelerS."
The modern airplane propeller is of
the detachable blade type, the separate
blades being keyed into hub. In the
case of the aluminium blades, they are
forged from aluminium bars. Drop
hammer forging presses bring the bar
to within one thirty-second inch of
the finished dimensions and the blade
is finished by machine and handwork
Finished blades are inspected for &C
curacy of dimensions, angle of twist
and other factors and are balanced
against master blade to secure abso-
lutte uniformity. Hubs are of chrome
Vanadium steel exquisitely machined to
to the engine cTankShaft.
1t is the practice of both Army and
Navy to subject to rigid tests on special
test stands at the Army Air Corps ma
teriel division base, Wright Field, Day.
ton, Ohio, all new experimental pro-
pellerS or standard designs which in
volve any change in blade dimensions
or in altered distribution of the metal.
Rigid Tests Imposed.
The Army has constructed at Wright
Field giant test stands on which pro-
pellers larger than any now in opera
ton may be whirled to the point of
failure. Experimental propellers or
those involving changed design are
given a 10-hour run at 100 per cent
overload and about 25 per cent greater
speed than they will get in operation.
Experimental designs, in addition, get
a 50-hour test to prove strength under
vibration.
The test stands are among the most
interesting of aeronautical test equip
ment. They are designed to take up
the terrific shocks when propeller,
revolving at tremendous speed, shat
ters. The force of blade, hurled
from its hub by breakage at high speed
is estimated as equal to that of a 4-inch
field gun fired at point blank range.
Safeguards must be provided to pre-
vent the blade causing damage when it
let's go. To care for the shock of the
motor, which might rip the whole test
stand apart, the giant electric engines
are bonded into mount composed of
scores of tons of concrete and steel,
embedded many feet in the earth. OBJ
servers are buried in a bomb proof
vault covered with several feet of wood
and metal, designed to take up the
| force of a direct blow from a shattered
blade. Observations are made through
a nariScnnA ARA anQenent 60 fnrrihle