Evening star. [volume] (Washington, D.C.) 1854-1972, 1928-07-22
WIND TUNNEL AIDS
PROPELLER STUDY
Scientific Tests Begun at
Langley to Find Basic Laws
for Blades.
BY COLEMAN B. JONES.

! BY the Associated Press.
LANGLEY FIELD, Va-Although
the propeller is one OF the most
! obviously essential paris of the air.
plane. scientific study of its design and
| behavior under various conditions Is
only now being started.
| This has been made possible through
| the construction here by the national
advisory committee for aeronautics OF
a huge wind tunnel in which actual
| fight conditions can be simulated by
mounting o full size atrplane with the
| fuseiage, motor. propeller. landing gear
and part of the winds in the path Of
an air current having a velocity up to
| ITO miles an hour.
| Trial and Error"
! All that is known about propellers
at present has been learned from
nearly but not quite exact observations
/ of their action after they were con-
structed. by the unscientific method OF
cutting them out, trying them and
making duplicates If they worked.
With the new research tunnel the
scientists of the committee staff expect
to find out the fundamental natural
laws which govern the success or
failure of propellers and thus to pro-
vide designers of the future with
exact knowledge on which TO base
their calculations.
It is known that the pitch Of pro-
peller blades Is altered by the COM
plicated variety Of pressures exerted
against their surfaces as they beat
through the air at different rates OF
speed, TO pull forward the heavy craft
behind them. and that the structure
OF the plane Itself enters into that
phenomena. It has never been pos
| sibIe before, however, TO measure pre-
cisely the extent and ascertain exactly
! the how and the why Of those altera-
| tons,
Measure DETECTION.
Now. by moving the wind into the
plane instead of driving the plane into
| the wind and by operating the motor
| Just as If 1t were in flight, research
workers can measure the detection OF
| the tips throughout the whole range OF
their speed of revolution.
| The tunnel itself is, IN effect. two
large megaphones fixed in opposite
rated by q space of about 20 feet, in
:; which the airplane can be mounted
| The front or entrance" cone Is SO feet
| square at the large end and 20 feet In
diameter.
A 1000 horsepower Diesel engine
| drives a 28-foot fan in the mouth Of
| the "exit cone" This draws in the
air, which is turned into passages run
| ming along each side Of the structure
toward the front. There 1t Is turned
| again into the large opening Of the
entrance cone" It flows in with q
velocity of only 20 miles an hour. but
| is intensified to ITO by the time II
reaches the 20-foot opening.
Other Plane Studies.
While the tunnel was constructed
primarily for investigation of propel-
lers. it affords an opportunity also for
study Of many other urgent problems
affecting the design Of airplanes.
These relate to the cooling OF air
cooled engines, the cowling of all types
of engines, the air resistance Of these
and other parts Of the structure. includ-
ing the landing gear and junction points
where wings and fuselage join, the an
forces that affect the ailerons and the
tail surfaces on which control Of flight
depends, wing ffutter and the drae
caused by wing radiators and the fuse
lage.