PLATE XI.—AN AIRMAN’S POINT OF VIEW.
Sheets of water are excellent guides when flying. Trees show up clearly, too; also roads—as may be seen from the one curving at the extreme right of this photograph, which was taken from a biplane piloted by Mr. Grahame-White.
When flying above land, the making of leeway may be nothing more than an annoyance; but should the pilot be passing above the sea, between coasts many miles apart, this side sweep of the wind may be a peril. One of the grim tragedies of aviation is attributed to leeway in a wind. Leaving France on a flight to England, Mr. Cecil Grace was driven from his course by a wind which blew up Channel towards the North Sea. There was fog, too; and as the pilot was using an early type compass, it may have failed to register accurately. At all events, he never reached the English shore. Seen once while in flight—and this by a fishing-smack—he was lost in the mist, flew wide of his course, and passed out to the North Sea instead of towards the cliffs at Dover. From that day to this his fate has been a mystery, although it is true that not long after he vanished his flying cap and goggles were washed upon the beach near Ostend—mute but tragic witnesses to the ending of his flight. But of the airman’s body, or of the wreckage of his machine, nothing was ever found.
Fig. 66.—Effect of a side wind.
A. Starting-point; B. Point steered for; C. Point actually reached; D. The course flown by the machine, owing to the pressure of a southerly wind.
It is possible, with a modern-type compass, to make an allowance for leeway. The airman studies a gauge before he ascends, ascertaining the strength at which the wind is blowing. Then he sets a pointer upon his compass by which he may correct, even while passing through the air, the sideway thrust of the wind; that is to say, should he be flying to some point due east of his starting-point, as was assumed in [Fig. 66], and should the wind—blowing from the south across his path—tend to force him towards the north, then he would set his pointer so that he was steering not due east, but to a point a certain number of miles south of east. In this way, with the wind driving him always north, he would arrive not at the imaginary destination towards which he steered, but at the real point due east which he desired to make. The drawback of the method may be this: should the pilot leave ground in a 10-mile-an-hour wind, and should the strength of this wind increase say to 20 miles an hour, his allowance for leeway would be insufficient; but against this may be set the fact that the airman, becoming aware probably, by the increased rolling of his machine, that the wind was tending to strengthen, would steer still wider of his goal. Compasses are being tested, also, which allow pilots to make an accurate and mechanical allowance, even while in flight, for risings or fallings of a side wind. There is one, a form of transparent compass, made so that the airman can look down through it, and see the ground passing away below. Selecting landmarks with his eye which are a little distance apart, he is able to note—by contrasting his compass-course with that his machine makes when in relation with these objects—just how much drift he should allow for. Then he alters his leeway indicator and makes another observation later on, should he think the wind has changed again.