The record-union., 1898-11-09
A NEW FLYING MACHINE.
Intended Alternately to Climb and
Slide Down HILL

S110o OOWA k11AX.
Mr.. Davidson, who gave a popular
account of his projected air car before
the Aeronautical Society yesterday af-
ternoon, may be tersely described as
the freefance of aeronauts. Most flying
machinists are at present agreed that
the simplest way to secure aerial fight
is by forcing an inclined plane forward
through the air by means Of horizon
Etals back thruSt-in other words, the
principle of the moered kite, where a
motor takes the place of the mooring.
Some inventors, such as Maxim, sup
ply the back thrust by means of verti-
cal rotary fans placed astern. Others,
such as Langley, make use of Tapping
wings similar to those of birds. Mr..
Davidson differs from all these in
avoiding back thrust altogether. His
theory is to lift the machine vertically
by means of rotary fans placed hori-
zontally within the large wing surfaces.
and then secure the motion forward by
allowing them to slide forward down an
inclined plane by the gravity of the
whole machine. He believes his rotary
fans are alone able to lift the machine
up to the required hight, and he trusts
entirely to gravity for the forward mo-
ton. Mr.. Davidson uses vertical lift,
Mr.. Maxim horizontal thrust, while
Professor Langley may be said to en-
ploy the via media" of inclined wings,
whereby both principles come into op-.
Grafton.
The main difficulty appears to lie in
the fact as to whether Mr.. Davidson's
fans will be able to achieve the neces-
So,~xy
may be possible to do without back
thrust, though it is an undoubted fact
that the birds employ both at times.
Mr.. Davidson has done more than talk.
He has had practical experiments made
with rotary fans under the superintend-
ence of w. G. Walker of Victoria
street, according to which he, claims
that a rotary fan four feet in diameter
was found to lift several times the
weight necessary for the structure, to-
gether with the weight necessary for
the propulsion of the fans.
Let US suppose, for the sake of ex-
ample, that the structure for the fans
and power weighs twenty pounds, and
that at a certain speed we get a lift of
twenty-five pounds. This means five
pounds to the good, which would be
quite enough to secure the result. The
bigger the fans, we are told, the better
the result; and here it may be men
toned as point in Mr.. Davidson's
favor that according to Lord Kelvin the
practical results Of the experiments
with Mr.. Maxim's rotary fans were
twenty times more favorable to the
aerial machinist than those which the
mathematical theories afforded
Mr.. Dayidson's statements regarding
the lifting powers he has obtained must
at present be considered sub judice.
They are entirely contrary to the opin-
Ions and results Of the experiments of
other investigators. For example, A.
M. Herring, a leading American avia-
tor, says that with the lightest engines
ne mas been able to secure he could not,
even under the most favorable circum-
stances, lift more than the bare weight
OF the engine itself. He considered that
with engines weighing more than four
or hve pounds per horsepower ''practi-
cal success with this type of apparatus
is not possible"
AT the same time it would be unwise
to throw cold water on Mr.. Davidson's
energy and optimism. The laws Of
aerial mechanics are still but imper-
fectly understood We need enthusiasm.
enterprise and experiment. If Mr.. Da-
wilson can prove his case even par
TALLY, progress will be gained. 1t is
probable that the flying machine which
will fly will embody no hard and fast
principles It will probably embrace a.
number Of eontributory principles
partly vertical lift, partly horizontal
back thrust, partly forward slide by
gravity-certainly a number Of details
IN the way of tail and wing movements
to meet those variable movements of
air and Wind which the most casual in
spection of what the lamented Lilien-
thai used to term "our masters in SAIL
ing flight" the birds, reveals as neces-
sary every moment
Nature has provided against contin-
genc1es and conditions many of which
are unknown and invisible to man. The
closer we can keep to the natural mod
els the better chance we have of sue
ceeding in initiating and coping with
natures conditions. Apart from his
rotary fan lifters, Mr. Davidson appears
to be endeavoring to follow out this
principle. The wings Of his machine
are shaped like those Of the larger birds
The tail is somewhat of natures pat
tern; and if he will not be too dogmatic
until he has successfully proved his
points, there seems no reason to doubt
that his experiments may considerably
advance the whole problem.-London
Chronicle.