The Leavenworth echo. [volume] (Leavenworth, Wash.) 1904-current, 1917-11-23
american AviatorS Won't Have
to Experiment While Flying
Over Enemy.
TWO PROBLEMS TO SOLVE
United States Bureau OF Standards
Has Devised a Way to Reproduce
the Conditions Found in High
Attitudes.

|
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
Ill American cirplanes 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 a few final tests in that little green
ish-gray building.
There will be determined, under con-
ditions almost identical with condi-
tions 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 Altitude 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 20,0OO-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 1t 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
| all the other things that he should do.
Being confronted with the necessity
| of making such tests, the bureau of
standards experts figured out a
| method.
The Two Problems.
First, they argued, they must know
| lust what an airplane does at an
altitude, say of 10000 feet. An engine
that will perform perfectly at 10000
feet has q tricky habit of stumbling"
and missing ignition when it gets an
other 10000 feet higher, and the ex-
20 oh
ments at that height.
Second, they wanted some sort OF
a mechanical arrangement which
w0ald permit them to test untried
| types 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 a con-
/ crese, tomb-like structure, about 10
feet long by feet wide and 81 feet
high. This concrete chamber was so
| constructed that 1t could be made
vacuum if necessary. The walls are
70 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
Mt sea level. That meant that when
| the scientists got to duplicating air
pressure at 10000 feet the walls had
| 70 support an outside pressure of air
/ equal to eight pounds to the square
inch. If the walls were not built thick
they would crush in like paper.
! Either Hot or Cold.
| Then complete heating and re-
frigerating plant was installed so that
when the four or six big fans which
| are to whirl the air over the engine at
40 miles an hour start their gale 1t
will be down to the temperature that
| one finds thousands of feet up.
Into this air chamber they expect
to put the engine type that is to be
tested, mounted so that 1t can tilt for
ward. backward or sidewise, just as 1t
would behave In the air.
AS soon as everything is ready the
doors are locked and made alright
and the engine is started. When 1t
starts. the air on the inside of the
chamber is the same density as the
outside air, but when the engine be-
gins to suck in air to make explosions
the inside atmosphere rapidly becomes
exhausted. The chamber is provided
with an intake valve which will admit
the air that is needed.
Observation Windows.
The chamber is also provided with
glass windows, through which the ex-
perts may watch instruments which
register the air pressure and the tenn
perature of the chamber. BY data Sc
| cured in actual flights the bureau ex-
perts know the exact density of the
air at each of the various hundred
foot levels An ordinary aneroid ba-
rolneter would give this data only APP
proximatcly When the engine starts
and begins consuming air on the in
side of the chamber the inside pres