The daily star-mirror. (Moscow, Idaho) 1911-1939, 1917-10-25
UNIQUE TEST FOR
LIBERTY ENGINE
American Aviators Won't Have
to Experiment While Flying
Over Enemy.
TWO PROBLEMS TO SOLVE
United States Bureau of Standards
Has Devised Way to Reproduce
the Conditions Found in High
Attitudes.

Washington.-The bureau of stand
ards is erecting a little greenish-gray
concrete building on the edge Of it's
grounds where one of the final chap
tiers of Americas preparations for
aerial warfare will be written. The
bureau declines to discuss what part
1T will play in the final design of the
new Liberty air engine" which the
government is expected to mount on
all American airplanes for use in the
European war; but it has become
known that before the final design Of
this engine is approved 1t must under
go few final tests in that little green
ish-gray building.
There will be determined under con-
ditiOns almost identical with condi-
tons found at various attitudes, just
how an airplane engine performs
when it gets so high that the air gets
perceptibly thinner. 1t will be tested
in a temperature down to freezing.
Bringing High Attitude Down.
The bureau building is a tomblike
structure, full of delicate instruments
(which will have the effect of bringing
the skies down to the earth, insofar
as airplane conditions are concerned.
1t is impractical to send an engineer
aloft to watch the engine perform up
there, so the bureau plans to bring
the skies to the engine.
Ever since the European war began,
the aviators of the warning nations
have been flying to astonishing heights
IN the clear air of France. Attitudes
of 10000 feet are quite commonplace,
and 20,000-foot flights no longer ex-
cite wonder. Aviators must go up
high, and they must have engines that
will take them there, so the engine
designers have been experimenting for
the last three years with an engine
that won't smother" when it gets into
thin air.
SO far the allies have been unable,
for various reasons, to make. absolute
ly accurate tests. An engineer can go
.aloft in plane, but he can't load in
a ton or two of apparatus also and
test out sparkling efficiency, compress
sion density, horsepower delivery and
NIL the other things that he should do.
Being confronted with the necessity
of making such tests, the bureau of
method.
n The Two Problems.
First, they argued, they must know |
1ust, what an airplane does at an |
altitude, say of 10000 feet. An engine |
that will perform perfectly at 10000 /
feet has a tricky habit of stumbling"
and missing ignition when it gets an
other 10000 feet higher, and the eX-
perts wanted to observe all its all
ments at that height.
Second they wanted some sort of |
a mechanical arrangement which
would permit them to test untried I
fypes of engines under conditions sim
liar to conditions very high aloft, and
to approve or condemn the perform
ance of these untried types.
So they set to work to build con-
crete, tomb-lke structure, about 10
feet long by 6 feet wide and 61a feet
high. This concrete chamber was so
that it could be made a
vacuum if necessary. The walls are
~ inches thick and tarred on the out
side. They needed thick walls be-
cause at 10000 feet altitude the air
pressure Is about seven pounds to the
square inch-about half the pressure
at sea level That meant that when
the scientists got to duplicating air
at 10000 feet the walls had
to support an outside pressure of air
equal to eight pounds to the square
inch. If the walls were not built thick
Ehey. would crush in like paper
Either Hot or Cold.
Then a complete heating and re-
rrigerating plant was installed so that
when the four or six big fans which :
ire to whirI the air over the engine at
10 miles an hour start their gale it
will be down to the temperature that :
me finds thousands of feet up.
Into this air chamber they expect
O put the engine type that is to be
ested. mounted so that it can tilt for
ward. backward or sidewise, just as 1t
would behave in the air.
AS soon as everything is ready the 0
oors are locked and made alright, !
nd the engine is started. When it e
tarts. the air on the inside of the e
hamber is the same density as the II
utside air, but when the engine be-
ms to suck in air to make explosions L
he inside atmosphere rapidly becomes a
Exhausted. The chamber is provided s
18th an intake valve which will admit | u
le air that is needed. "
Observation Windows. L
The chamber is also provided with Il
lass windows, through which the ex- it
erts may watch instruments which
.gister the air pressure and the tenn
srature of the chamber. BY data Sc
1red in actual flights the bureau ex- ci
,rts know the exact density of the FL
r at each of the various hundred n
4 l.. G.