The Watertown news. [volume] (Watertown, Wis.) 1917-1919, 1917-11-09


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 it 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-
rometer would give this data only ap-
proximately. When the engine starts
and begins consuming air on the in
side of the chamber the inside pres
the square inch to II pounds, to Ii
pounds, and so on, until 1T has reached
a rarity that corresponds to q great
height.
AS soon as 1t reaches this rarity the
intake valve Is opened slightly, and
only enough air is admitted to take the
place of the inside air that the engine
is consuming. This, of course, keeps
the pressure inside at the desired rar-
ity, and to all intents and purposes
the engine is now flying at an altitude
of 10000 feet.
General Mobilization.
AS soon as the engine starts, other
parts Of the chambers machinery start
too. For instance, the exhaust begins
to work. 1t would be utterly imprac-
ticable to discharge the gases from
the engine into the outside air through
the ordinary exhaust pipe. With the
air inside at seven pounds pressure
and the outside air at II pounds the
force of the outside pressure would
jam great quantity of atmosphere
back up the exhaust pipe, fill the
chamber with fumes and smoke and
no In CIR 70 81
To overcome this the experts de-
signed q blower attachment which will
suck the gases and fumes from the en-
CINE with force sufficient to prevent
the outside air from rushing in. Also,
the fumes and gases will pass through
pipes which spray these gases with
cold water, thus keeping down the
temperature in the chamber.
The actual horsepower performance
of the engine can be determined with
out trouble. Every ounce Of pull 1t
generates is transmitted to big cleo
trio generator on the outside, and the
amount of. electricity generated by the
engines power makes it perfectly SIM
pie for the scientists to determine
when the engine is faltering.
Through the glass doors of this con-
crete chamber, the scientists will OBJ
serve the engine itself or the instru-
ments attached, which will register
every performance of that piece of
mechanism. If 1t won't work in an
air-pressure of seven pounds to the
inch, that engine will never do for high
observation work.
Tests Pre-compression Also.
Broadly speaking, this is the chief
use to which that concrete chamber
will be put. 1t has another use, how
ever. That is the testing of pre-com-
preston devices. 1t has been found
advisable to equip all airplanes that
are expected to attain great height
with a pre-compression attachment.
This is designed to gather and con-
centrate quantity Of air and at the
moment of each discharge Of the cyl
inde-s, inject it into the cylinders to
supplement the deficient supply that
the engine can take through it's intake
valves.
There are many of these pre-com-
preston devices being offered to the
government, which at this time cannot
be proven except under actual battle
conditions, but with the use of the
rarified air chamber at the bureau, the
government experts can decide within
a few moments the uselessness or
value Of the device.