The Indianapolis journal. [volume] (Indianapolis [Ind.]) 1867-1904, 1901-11-17
The Problem Of Aerial Flight
PROF. SIMON NEwcoMB. IL. D.. F. r. S.

the friction Of the surface against the air
and consider only the pressure upon II
then the faster the aeroplane flies the les
the power required to keep IL supported. If,
however, Ii is to carry anything with it
and IL must carry its driving engine an
it's load-then the power required to over
come the resistance of the air will increase
as the cube OF the speed as in the case of a
steamship. driven through water. 1 may
here explain that while the resistance, in
pounds varies only as the square of the
speed, yet the engine power is measured by
the product Of the speed into the resistance
and this produces the cube. Thus to dou-
BILE the speed Of a steamer We must multi
ply the horse power of her engines by eight
and increase her daily consumption Of coal
In the same proportion. In the meantime,
since she completes her voyage in half the
time, the total consumption for the trip
will only be multiplied by four.
1t follows from this that the speed we
can secure has a practical limit, imposed
by the very nature of the case. But we
have some compensation in the fact that the
horizontal motion which is to sustain us in
the air need not be that of the whole ma
chine, but may equally well be that Of the
wings Of a horizontal windmill. Get the
wings at the proper angle, then apply a
power sufficient to make them turn fast
enough, and UP we go. Give a very slight
inclination to the axis of rotation Of the
wings and we shall soar forward. Alto
gether, from an ideal standpoint the flying
machine seems quite within our reach. But
before we can reach out and grasp it We
must go through a complicated course of
calculation based upon strength and
weight of materials, power of engines, heat
of combustion and laws of aerial resist
ance. Until We make this calculation we
are like the child to whom the task Of put
ting a ladder up to the moon seemed so
simple that he cried to nave it done.
Both the laws and the facts governing
the case are completely worked out by ex-
pertinent and we'll understood. The inven-
tor has only to bring these laws and facts
TO his aid to save himself a great deal Of
time and money which might otherwise be
expended in making machines that could
not fly. Let him put his machine on pa
per, giving material and dimensions of ev-
cry part. and then call in the aid of the ex-
pert physicist. The latter can determine
in advance what lifting power the machine
will have. If this prove equal to the
weight of the machine plus that of the
man who can guide it the problem is
solved. If this power is found to be only a
little greater than the weight Of the ma
chine we shall have something that will fly
but will not be of any use.
SOME OF THE POSSIBILITIES
In this way the subject may be brought
very largely within the range Of mathe-
NAUTICAL demonstration. What can we say
of the ultimate outcome? On the affirma-
tive side only this: that no one has yet
demonstrated the absolute impossibility of
accomplishing the desired feat. What Is
certain is that no one will every fly to any
great height or to any considerable distance
until some metal or alloy is discovered
which will combine strength with lightness
in a far higher degree than any metal or
alloy at present known to US. There are
limitations, too, at every turn upon what a
machine can do. The speed with which a
rotating apparatus of any sort can turn
has its limit. The larger its size the fewer
turns it can make in a second. Let us con-
slider the central axis as at rest. Then the
extreme speed of the outer circumference
as 1t turns can never exceed a few hun
dred feet a second without the centrifugal
force -endangering the machine Just how
many hundred feet will depend upon the
skill OF the inventor In combining his ma
terials, but if he ever approaches a speed
of a thousand feet a second his whirligig,
whatever he makes it of, will fly TO pieces
by its own centrifugal force. This is a
force which admits of no evasion or COM
promise.
Again, the best possible machine will re-
quire a certain horse power and the guam
tity of coal mr. npfr0larm raouired m nro-
duce this horse power can be determined
We are also met at every point by the law
that, while the weight of the machine in
creases as the cube of its dimensions, the
power which it can generate will increase
only as the square. 1t is curious how the
latter law Of increase extends to every
detail, strength of boiler, steam-producing
capacity and centrifugal force. 1t follows
that the smaller our machine the greater
the fraction OF it's own weight which it
can possibly carry. and, max it as effect
i've as we please, there will be a limit to
its size beyond which it cannot carry more
than it's own weight. 1t has been suggest
ed to the writer that by making a number
of small machines a combination may be
effected which would have an advantage
over any single machine that could be con-
structed. This idea is a very interesting
one which some inventor may amuse him
self in carrying out. But, granting all
reasonable hopes, it must be admitted that
the prospect of ever having a flying ma
chine which shall supersede our present
methods of transportation does not seem
at all encouraging.
! Washington, D. c.