Evening star. [volume] (Washington, D.C.) 1854-1972, 1928-08-05
AIR ENGINE DRAG"
SUBJECT Of STUDY
AeronauticaI Scientists Esti-
mate Horsepower Involved
and How Employed.

The resistance or drag Of A
Wright "Whirlwtnd" engine mounted in
q plane travelling at 100 miles per hour
valuable data long desired by builders
Of sirplanes equipped with the 'whirl-
wind" in particular and ra6lal air.
cooled engines in general-has been de-
termned bv Government aeronautical
scientists to be such that it is estimated
90 Of the 200 horsepower rate. by that
engine is utilized 10 push the power
p.ant through the air while the re-
usiNder II devoted to cariX the
plane along in fight.
The drag" of the engine was deter
mined after long tests in the gigantic
win6-tunneI Of the National Advisory
Committee for Aeronautics at Langley
Field. Va. the largest Of its kind and
the most efficient piece Of equipment IN
the world A full-Scsle airplane Is
mounted in this tunnel and wind Is
blown through Al 100 miles an hour
END faSte~ giving actual f1vinG condl-
tions while the committees engineers
make studies that are virtually i'm
possible if the plane were IN fight.
Tests when Plane Is Spceded.
The drag" Of the engine. equipped
uith individual exhaust stacks for each
cylinder. at 100 miles per hour Of speed
v'ss found by the committees Sclen-
fists to be IS pounds, which, IN effect,
represents that energy equivalent
to that weight is required 70 haul the
engine through the air. II also slgni-
fes. according to rough estimates. that
an increase in speed Of about Is miles
per hour is lost through the drag,
and the lost speed represents about one
ard 0ne-haf gallons Of fuel per hour
The purpose of determining the
"draC" is to devise ways and means OF
reducing the big frontal area offered by
the rsdial type engines III such man.
ner that more speed and longer cruising
radius may be obtained without the
expense Of adding additional horse
power. The tests made by the Advisory
Committee we're with the engine "un-
cowlod" is, mounted on the nose
Of the fuSelage without envy stream
lining effect whatever. Streamlinlng or
"cowling' is calculated to reduce this
drag Of the engine. Further tests are
IN be made with the engine under va
ri9us degrees Of cowling until the peak
Of Stresnlining is reached. wherein the
engine would be inclosed entirely in
metal
Provision Made for Cooling.
Provision in this respect is made for
cooling by letting the air in at the nose
and out through holes in the side
With an engine Of the radial type.
which is in effect a fiat surface resting
At right angles to the path Of fight.
eowled TO the point where the nose of
The plane tapers down like cigar the
greatest if not the only. disadvantage to
this type Of power plant viii be re-
moved Such a condition. however.
could hardly be brought about without
extending the crank-shaft of the pro-
reller. as the hub Of the shaft now rests
almost right UP against the engine
The water-cooled w. type engine
offers perfect streamlining possibilities
and hence more speed but the radiator
the frontal area it sets up in all types
except when built into the wings as a
FIAT surface - still is the problem !
However, it is learned that experiments I
row are going forward with a type Of /
fluid that has higher boiling point /
TRAN water. in which event the size Of .
fhe radiator could be reduced materially i
and therefore less drag" would ha 4
present.
Committee Finding Outlined.
The findings Of the Advisory COM |
mittee illustrate the attention being /
given 10 refinement Of present aircraft !
parts with the view of obtaining better
performance, safety and economy in
operation. II the frontal area of an
sir-cooled radial engine could be re-
ouced so or IS per cent and the landing
gear. which has been found TO contrib
ute 90 per cent of the total drag" of
an sirplane fuselage. could be eIin1i-
mated in fight entirely. an enormous
increase IN speed, q greater cruising
radius. saving in fuel and better all
around performance would result with
tFle same expenditure Of horsepower
that nov is being used