Together with his assistants he found a suitable place for experiments
among the sandhills on the shore of Lake Michigan, about thirty miles
eastward from Chicago. Here a hill about ninety-five feet high was
selected as a point from which Chanute's gliders could set off; in
practice, it was found that the best observation was to be obtained
from short glides at low speed, and, consequently, a hill which was
only sixty-one feet above the shore of the lake was employed for the
experimental work done by the party.
In the years 1896 and 1897, with parties of from four to six persons,
five full-sized gliders were tried out, and from these two distinct
types were evolved: of these one was a machine consisting of five tiers
of wings and a steering tail, and the other was of the biplane type;
Chanute believed these to be safer than any other machine previously
evolved, solving, as he states in his monograph, the problem of inherent
equilibrium as fully as this could be done. Unfortunately, very few
photographs were taken of the work in the first year, but one view of a
multiple wing-glider survives, showing the machine in flight. In 1897 a
series of photographs was taken exhibiting the consecutive phases of
a single flight; this series of photographs represents the experience
gained in a total of about one thousand glides, but the point of view
was varied so as to exhibit the consecutive phases of one single flight.
The experience gained is best told in Chanute's own words. 'The first
thing,' he says, 'which we discovered practically was that the wind
flowing up a hill-side is not a steadily-flowing current like that of a
river. It comes as a rolling mass, full of tumultuous whirls and eddies,
like those issuing from a chimney; and they strike the apparatus with
constantly varying force and direction, sometimes withdrawing support
when most needed. It has long been known, through instrumental
observations, that the wind is constantly changing in force and
direction; but it needed the experience of an operator afloat on a
gliding machine to realise that this all proceeded from cyclonic action;
so that more was learned in this respect in a week than had previously
been acquired by several years of experiments with models. There was a
pair of eagles, living in the top of a dead tree about two miles from
our tent, that came almost daily to show us how such wind effects are
overcome and utilised. The birds swept in circles overhead on
pulseless wings, and rose high up in the air. Occasionally there was
a side-rocking motion, as of a ship rolling at sea, and then the birds
rocked back to an even keel; but although we thought the action was
clearly automatic, and were willing to learn, our teachers were too
far off to show us just how it was done, and we had to experiment for
ourselves.'
Public-domain text, read in full here on John Shaqi.
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