The Washington times., 1922-06-03
WASTEDPOWER
CAN De TRACED
To FAST RIDING
Gas Loss Increased by Air Re-
sistance, But There Are
Other Factors.

Here is a problem for the motorist
to ponder the next time he hits the
open road for a fifty.mile or more
trip.
That an automobile travelling
twenty-five miles an hour on a fifty
mile run will consume less gasoline
than IL 1t were travelling forty-five
miles an hour, is the declaration Of
certain authorities on phyAics and
mathematics at Leland Stanford, Jr.,
University.
Try it out. Here is what the ex-
perts say:
The primary reason for this con-
clusio Is found In the fact that the
greater the speed, the greater In
proportion the resistance OF the air
becomes. Stated in terms OF mathe.
matics, the air resistance Is as the
square of the speed. Thus a car
going two miles an hour has to use
four times the pressure that a car
travelling one mile an hour would.
At forty miles an hour, the auto
mobile uses roughly 1922 times as
much energy in overcoming air re-
sistance as one travelling twenty-five
miles an hour does.
Heat Is Wasted.
Several other factors enter into
the problem such as he heat gen.
Grated by the engine whi IN goes 10
waste, gas mixture incolnpltly burn
ed, and loss of the power from .Ihe
engine through less traction on the
road, all tending to make the con-
sumption of gasoline nigh at high
speed.
In running an automobile at high
speed there would normally be tho
same number of revolutions and ex-
plosions occurring in the engine in
travelling a certain distance that
there would be at low speed. But
the fact that the automobile shoots
forward under a higher speed tends
to raise its wheels a tritle off tine
road. by centrifugal force. an effect
further increased when the machine
bounces from the crest of one bump
to another. instead OF riding the
slopes OF the depression. This les.
seninR OF pressure of contact with
the ground. with a consequent slip.
ping and bouncing OF the rear
wheels from the road at higl speed,
means that the engine will race,
much like the engine OF \ steamship
when the propellors are thrown out
Of the water by wave action.
Engine Heat Varies.
The heat Of an engine will vary,
almost directly with the speed OF
the engine. II the engine were to
turn over the same number Of times
in making the run at twenty-five
miles an hour that II did when
travelling forty-five. the wastage OF
gas from heat generation would be
very nearly the same at either
speed. But, as has been pointed
out. the engine will probably have
to make many more revolutions to
cover the same distance at high
speed, and the heat generated in
these additional revolutions Is a
loss above that sustained from
wastage at twenty-five miles an
hour.
The question OF incomplete COM
bustion of gas in the engine is one
which presents several angles. AS
general statement. II might be
said that when an engine runs at
high speed there is a tendency for
the exhaust stroke to come SO
quickly after the firing OF the gas
oline vapor that portion OF the
mixture is expelled before all OF
II has burned and has delivered it's
energy to the piston.
Whether this would make a per.
ceptible difference between the fuel
consumption of car driven at
twenty-five miles an hour and
forty-five miles an hour would de.
pend a great deal upon the particu-
lar make Of engine. The timing
and functioning Of the valves is
usually adjusted by the manufac-
turer so that the car will not have
this fault within the recommended
and guaranteeing speed.