The sun., 1894-05-13

com bined IN Design Wnlcn SNAIL ueal Win
the general problem as q whole. OF these
separate conditions or problems. Mr.. Chanute
snumerstss ten. but proceeding to discuss
them in detail. he shows that many Of them
have been approximately solved. especially
since 1889. and that concerning several others
a,better understanding Of the fnculties to be
surmountsd has been attained.
The nrst problem considered 10 that pertain
ing to the resistance and supporting power Of
the air. Up to . few yenrs ago IL could not be
determined By the use OF the then current
formulas how birds were supported In Night
Now. however. that Prot Langley's experi-
msnts have confirmed many previously
tried. one may accept the empirical formula
OF Duohemin with reference to lift" and
drift" a. approximately correct, and figure
out the support and the resistance with con-
fdsncs that We shall not go far wrong. These
calculations seem to indicate that artificial
flight is possible. even with planes; that very
fiat angles Of Incidence. from 20 to %. formerly
considered inadmissible. will in fact be the
most advantageous. and that within certain
limits OF hull resistance" high speeds will
require less power than low speeds. because
they admit Of obtaining support from the air
ct fatter angle. Mr.. Chanute shows 10 the
body Of his book that the drift" dlminishes
% the angle OF incidence becomes less. that
the hull resistance" tincluding car. framing.
braces. &c.) increases as the square OF the
speed: tina. the skin friction 10 SO
small that II may for the present be
disregarded and that Il Is now possible to cal
culate. approximately ut least, the power re-
ouired to obtain support with pianes. and to
overcome the resistance. although We arc not
ret aware what limit will be i'm posed upon the
II - al -. ak.N q 4.
weight will increase as tho cube. while the
sustaining surfaces will grow only as the
square OF the similar dimensions. 1t is further
to bs noted that the formulas which give this
promise OF success were derived from expert
ments with plano surfaces. whereas II 10 al
ready known that tconcavo-convex surfaces will
bs still more effective. although the most favor
able shapes are not yet precisely ascertained.
This statement indicates tho direction which
scientific investigation and experiment should
now take. and holds out the hope that the flrst
sub-proIlsm is in fair way Of being solved.
The second sub pro blem. which 10 concerned
with the motor to be employed. was for long
time considered the most unsolvable II
seemed HOPELESS to attempt to rival with an
artificial motor the output OF energy apper-
tanning to the motor muscles Of birds. which.
there 10 reason to believe. develop work In or
dinary flight at tho rate Of one horse power to
twenty pounds OF weight. and can. for Q brief
period 10 rising. give ont energy at such rate
as to represent an engine developing one
horse power and yet Weighing only Ave or six
pounds. The lightest engines In use In 1890
weighed. including the generator Of power.
90 pounds per horse power for steam. 81
pounds per horse power for gas engines. and
130 pounds per horse power for electric mo-
tors. Since 1890. however. marine lyAchtI en-
gines have been reduced more than ons-halfi In
weight. Mr.. Hargrave has produced steam
sngins Weighing but l0.7 pounds psr horse
power. n Maxim has created one Weighing
but pounds per horse power. including
condenser. and other expsrlmsnters
have Appropriated closely to the same
wsightA Steam engines. therefore. seem
70 have been so much reduced in weight
a. to admit OF their being employed
as motors for flying machines. This. how
ever II not put forward by Mr.. Chsnuts as .
dnAl solution. for II may be that as has been
limited by NJ. Maxim. some form OF gas or
petroleum engine will prove to be still better
adapted to aerial motion. Meanwhile. It 10
possible to utilize still lighter power. for Mr..
ChAnuts demonstrates In the body OF this
book that the wind may be turned to account
under favorable circumstances. and that IL
will furnish an extraneous motor which costs
Aothing and imposes no weight upon the Ap-
paratus just how much wind power can be
utilized cannot we'll be told In advance OF
experiment but the author estimates that
under certain supposed conditions II may be
IS much as six horse power for an aeroplAns
with 1000 square feet OF sustaining surface;
and II Is also pointed out that. while but few
experimsntsrs have Tesorted to the wind as a
motor. these few have accom- plIslsd remark
able results