Ripley County democrat., 1917-11-02
with all intake valve which viii admit
the air that Is needed.
Observation Windows.

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 se-
cured In actual fights 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 or the chamber the inside pres-
sure begins to drop from 10 pounds to
the square inch to IA pounds, to 13
pounds, and so on. until It has reached
rarity that corresponds to q great
height.
As soon as It reaches this rarity the
intake valve is opened slightly, and
only enough dir 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 Us the engine starts, other
parts Of the chambers machinery start
too. For instance, the exhaust begins
to work. It 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 Dir at IT pounds the
force Of the outside pressure would
jam q great quantity of atmosphere
back up the exhaust pipe, All the
chamber with fumes and smoke and
reduce the inside pressure to normal.
To overcome this the experts de-
signed blower attachment which win
suck the gases and fumes from the en-
gine 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 It
generates is transmitted to big cleo
trio generator on the outside, and the
amount Of electricity generated by the
engines power makes II 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 win 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-compresslon Also.
Broadly speaking, this is the chief
use to which that concrete chamber
will be put. It has another use, how
ever. That is the testing Of pre-com-
preston devices. II has been found
advisable to equip all airplanes that
are expected to attain great height
with pre-compression attachment.
This is designed to gather and con-
centrate quantity Of air and at the
moment Of each discharge of the cyl.
inders, inject 1t into the cylinders to
supplement the deficient supply that
the engine can take through Its 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
rarifed air chamber at the bureau, the
government experts can decide within
few moments the uselessness or
value Of the device.