Evening star. [volume] (Washington, D.C.) 1854-1972, 1930-05-18
AVIATION
BY JOSEPH S. EDGERTON.

1CdOCIS VI U1lC dfldGAOl1
duStry in this country of the po-
sition Of the national advisory
committee for aeronautics as the
foremost aeronautical research
body in the nation, if not in the
world.
The first of these was the de-
cision by special committee of
the National Aeronautic AsSoci-
alton that the development by the
advisory group Of the now famous
N. A. C.. A. cowling for radial air
cooled engines constituted the
outstanding aeronautical achieve
ment of 1929 and so merited the
award of the coveted Collier
trophy.
The second was the fifth annual
aircraft engineering research con-
ference held during the past week
at the Langley Memorial Research
Laboratories of the committee at
Langley Field, Hampton, Va, be-
tween executives and aeronautical
engineers of the aircraft industry
and representatives of the Army,
Navy, Department of Commerce,
and Bureau of Standards with
Va U11C CO1111ll1OICC dIlNA 40
technical staff.
Research Accomplishments Shown
The conference brought to the
attention of the industry notable
results in aeronautical research
accomplished by the committee
during the past year and revealed
plans for still more far-reaching
studies to be pushed during the
coming year.
Building Giant Tunnel.
In its 20-foot propeller re-
search wind-tunnel, which result
ed among other things in the pro-
duction of the N. A. G. A. cowling,
the committee has the worlds
largest wind-tunnel. This tunnel,
however, is to be dwarfed by a
giant tunnel now under conStruc-
ton, in which entire airplanes
may be mounted for study. The
great tunnel Is to be 80 by so feet
In dimensions across the throat
and in this huge opening winds of
from 100 to 100 miles per hour will
be produced by engines totaling
5000 horsepower and driving two
manipulated propellers each 80
feet in diameter.
The foundations of the tunnel
and the building which will house
it are nearing completion and the
steel is on the site for the frame
work. Though 1t will be some
time before the tunnel is COM
pIeted, the research program al
ready formulated and requests
received for studies which will re-
Quire employment of this tunnel
assure for 1t an exceedingly busy
future.
The same is true Of great sea-
plane test channel half mile
long, IS feet wide, and Is feet
deep, now well under way at Lang
ley Field, in which Sorely needed
studies Of seaplane pontoons and
flying boat hulls may be made at
speeds ranging up to o maximum
OF go miles per hour. This chan
mel Is expected to do for seaplane,
flying boat and amphibion floats
and hulls what the wind tunnel
has done for the remainder of the
airplane. Hulls and floats which
will be much stronger, more sea-
worthy, better for landing and
taking off, and safer in general
are expected to result from use of
the channel, which also may be
used for speed boat design work.
There will be no test channel in
the world 10 compare with this
whsn It L. completed.
Travel at Speed Of Sound.
The committees study Of the
effects on the air of airplane pro-
peller tips travelling at approx
mately the speed of sound, as they
do with the modern high-speed
avition engine, is leading to start
ling new theories in propeller and
afrfoil design. It has been found
that the conventional propellers
Of today are efficient only up to
approximately half the speed Of
sound, but that above that point
efficiency begins to fall of rapid
1y. This means that with present
engine speeds the effect Of pro-
peller tips of the present designs
not only Is not useful but may be
actually harmful as far as per-
Torrance is concerned.
The cross-section of the present
airplane propeller is identical with
that Of certain types Of airplane
wings. For tremendous speeds,
however, studies now being made
show that radical departure from
this cross-section Is needed. It
has been revealed that cross
section fiat on one side and with
the arc Of a circle for the other
side Is much more efficient than
the present type at high speeds.
The result may be that the cross
sections Of future propeller tips
may be radically different from
that Of the remainder Of the
blade, with corresponding in
creaSes in speed and efficiency.
The wind tunnel in which tests
Of air-flow around propeller tips
are conducted is one OF the most
interesting of the many scientific
wonders at the Langley Field lab
oratories. In this tunnel wind
speeds up to 900 miles per hour
are obtained. At this tremendous
speed moisture in the air Is con-
verted into fog in the mouth OF
the tunnel and this vapor, rushing
around the test object, reveals
clearly and accurately the direc-
ton of the air flow. The shrek
ing of air at the speeds attained
in this tunnel is 80 penetrating as
to be acutely painful to the aver
age listener.
0;I Surav G%udhoN