The New York herald., 1922-10-29

flight. variously designated as gliding.
soaring and sailing. have attracted con-
siderable attention and much discussion
has arisen as to the practical and mill
tary value of this new development as
well as TO its scientific significance.
While many authorities anticipate moth
ing more than the, emergence of new
sport" and ascribe little importance to
motorless flights, others of a more imag-
NATIVE turn Of mind foresee great possi-
bilities In this type Of aerial navigation.
The motorless flying machine has even
been proclaimed as heralding the doom
OF the engine driven airplane
1t is certainly premature to attempt a
forecast of the future of flight in a
glider. The art Of gliding Is Of course
older than that of flight in an engine
driven machine: Lilienthaps experi-
ments with gliders were made mors
than generation ago. long before any
airplane containing a motor rose into
the air and executed real flight. But
Lilienthal. Pitcher. Chanute. Orville
Wright and others were not able to
stay aioft In q glider more than a few
minutes; whereas during the recent COM
petitions In Germany Martens remained
in the air nearly three-qusrters of an
hour and Hentzen stayed In the air two
hours, and later three hours. performing
eyolutions Of an intricate character. 1t
Is therefore clear that the art of gliding
has entered upon q new phase and the
scientific problems involved merit care
full discussion.
AS already indicated there is consid-
cradle diversity In the names given to
the flights thus carried out without the
aid of a motor. All the three names
mentioned above are really unsuitable.
The term gliding is reminiscent OF de-
scent in an airplane, while the real in
terest Of recent events has been In the
fact that pilots were able to stay In the
air very long without the help of a mo-
tor, and in fact performed climbing
feats. The term soaring is less insult
able, but it suggests climbing as the es-
sentia thing. whereas In reality, hori-
zontal flight in glider Is just as differ
ent from airplane fight as climbing in a
glider. Finally sailing Is quite inappro-
pirate as a description Of the flight In
question. Perhaps the term wind flight
is really suitable name for flying with
out motor as distinguished from en-
gne fight in an airplane.
The wind is indeed the main instru-
ment of motorless fight. Whether birds
and other natural fiiers do or do not
derive energy from the air In some
mysterious manner Of which We have as
yet no knowledge Is o question that
does not arise In the present connection.
The successes achieved have been the
outcome of careful study Of design and
of movements in thy air. In construc-
tion the gliders usSh look like airplanes
without engines and the determining
factors in the flights were the various
types Of winds that blew while the ma
chimes were in the air.
1t is clear that In a quiescent atuos-
phere the net result of any motion
through the air In motorless machine
must be diminution In the total energy.
(. e., in the sum of the kinetic and po-
tential energies. 1t follows that In the
absence of wind real fight. namely.
fight In which the machine maintains
it's level for some considerable time or
rises still higher above the ground, Is
not possible without source Of energy
like an engine. 1t Is the presence OF
wind that puts In the hands of the pilot
a source Of energy which can be used to
neutralize the loss Of energy Involved IN
motion through the atmospheric resisting
medium.
Although 1t should be obvious that the
wind must be upward or unsteady IN
order to supply this energy 1t ts neces-
sary to say a few words about the case
of steady horizontal wind, since It has
been claimed that "once the airman has
left the ground he gets his energy from
the wind, which may be level and
steady" That Is not correct. as can be
proved quito simply. II we write down
the equations of motion OF glider
through the air under the action Of
gravity we get three types of terms
(1) Accelerations In terms Of the motion
Of the glider relative to the earth; (2)
Gravity components; 60 Forces and
couples due to air resistance, these being
functions Of the motion OF the glider
relative to the air,
It Is useful to write the drst TERMS
the accelerations, with reference to the
motion Of the glider relative to the AIR.
When this Is done for steady wind
the resulting equations are exactly OF
the same form as II there were no wind
at all. since the moving ''air axes move
uniformly as seen from the earth