Evening star., 1941-02-20

production, which have, they
charge, brought pursuit airplane
production to a standstill for nearly
three years. Failure to deliver
first-rate pursuit airplanes has
given American aviation its worst
"black eye" from the European
viewpoint, they say
Because of the diverting of Army
funds into the liquid-cooled engine
field, one of the two leading manu-
facturers Of air-cooled engines had
to drop 20 per cent of its skilled
personnel, at that critical period
in American aviation development
following Munich. But for French
orders, which tided it over until
opening of the real American de-
fense program, this company might
have been forced to stop produc-
ton entirely, according to it's lead
ers. The effect on American de-
fense and aid to Britain would have
been disastrous, since this company
today is producing nearly half the
total number of military engines
turned out in the United States.
Liquid Cooling Costlier.
AS a result of the Army decision
to swing back to the liquid cooled
engine, there is only one American
manufacturer who has stuck to the
air-cooled pursuit for the Army
Republic Aviation Corp, which has
been given only relatively minor
orders, as compared with those for
iquid-cooled pursuits.
The iquid-cooled engine is vastly
more expensive than the air-cooled
type today. Although official unit
costs have not been announced, it
is estimated that the Allison engine
costs about $4,000 today, while an
cooled engine of the same horse
power costs $4,000 and an air.
cooled engine of twice the horse
power costs about $4,000.
Supporters of the liquid-cooled
engine contend that because of
better stresmlining possible in air
planes built around this engine,
far less horsepower is required for
the same performance. They have
compared the Bell Aira cobra, with
1000 horsepower Allison engine,
with the new Navy Vought-S -Sikorsky
F-4-U fighter, with a 1000 horse
power engine, contending that there
is less than per cent difference in
speed and performance between
the two, despite 100 per cent diff
ference in horsepower.
Say Comparison Not Justified.
Such a comparison is not juSti-
fed. according to officials of United
Aircraft They say that the Aira-
cobra is radically new design with
a submerged" engine behind the
pilot. while the Vought is a con-
ventional type with the engine
ahead The Vought, moreover, has
three times the range of the Aircobra
and, thanks TO its power, can carry
armor, guns and fuel that cannot
be matched by the smaller plane,
they contend.
A fairer comparison. they hold,
at least until submerged air-cooled
installations are possible, is between
the Curtiss P-36 pursuit airplane
with an air-cooled engine, and the
new Curtiss P-40 of about the same
size and type, with liquid-cooled
engine. The P-36. they point out,
is in the 300-310 mileS-per-ho
range, the P-40 in the 360-365 mile
class. The increased speed, they
argue, is not due to the superior
efficiency of the liquid-cooled en-
gine, but to increased aerodynamic
efficiency of the airplane resulting
from advances in the science since
construction of the P-36 was sus-
pended several years ago. If the
same aerodynamic refinements had
been applied to the P36, with its
air-cooled engine, they argue, it
would be just about as fast as the
P-40 with its liquid-cooled engine
and would have about the same
overall performance.