BLÉRIOT MONOPLANE
The first and probably best known monoplane, the Blériot, still holds many records for both speed and endurance. The Blériot machines have so many variations that it would be impossible to describe all the types of monoplanes this versatile Frenchman has turned out. We are familiar in a general way with the Blériot, the single widespreading main plane, set at a slight dihedral angle, with its long, graceful body out behind terminating in the horizontal elevating and vertical direction rudders, giving it the appearance of a great soaring bird as it sails through the air as steadily as an automobile on a smooth road—much more steadily in fact, for as soon as the wheels of an aeroplane leave the ground all jolting disappears, and not even the vibration of the engine is noticeable, although the roar of its explosions can be heard a great distance. There is nothing but the breeze and the earth streaming along behind you, as if it were moving and you were hovering motionless high up in the sky.
In the famous Blériot XI, in which the designer made the first trip across the English Channel, the main plane had a spread of a little more than 28 feet and a depth of 6-1/2 feet, a total area of 151 square feet and a low aspect ratio of about 4.6. At the end of the stout wooden framework, that made up the body and tail, was the vertical direction rudder 4-1/2 square feet in area which was turned from right to left by a foot lever. The elevation rudder was divided into two halves, one part being put at each side of the direction rudder. The total area of the elevator was 16 square feet, while the horizontal stabilizing plane to which the elevator was attached was about the same. The balance was maintained by warping the main plane, but instead of warping the tips of the plane, as is done in the Wright biplanes, the two sides of the main plane were warped from the base, so that the operator could change the angle of incidence—that is, the angle at which the planes travel through the air. Thus, if the machine should tip down on the right side, the operator would warp the planes so as to increase the angle of incidence on the right side and lessen it on the left side. In other words, the rear part of the right wing would be bent downward, while on the left side the rear edge would be raised. The forward edge remains stationary. The increase of the angle on the right side would cause an increase of the lifting power on that side and also the decrease of the angle on the left side would lessen the lifting power of the left wing so the right side, which was tipping down, would be lifted, and the machine restored to an even keel. This warping was done by moving from side to side the same lever on which was mounted the steering wheel. The whole machine was mounted on a strong chassis with wheels for starting and alighting. The pilot sat in the framework above the main plane. The monoplane was propelled by a single propeller of the tractor type 6 to 7 feet in diameter, placed at the front of the machine. It was driven in the early Blériots by a 23-horsepower Anzani motor, but more lately the Blériot machines have carried Gnome motors.
One of the important improvements which appeared on the No. XI bis was the changing of the main plane so that the upper side was curved but the under side was nearly flat. This gave the machine much more speed and the designers found that the flattening out of the curve on the under side did not greatly lessen the lifting power. This same type of machine also was made later to carry three passengers. The machine known as the "Type Militaire" was just about like the others except that the tail instead of being rectangular was fan-shaped. It carried seats for two and was equipped with all the latest aviation accoutrements, such as tachometers, barographs to record altitude, instrument to record inclination, various other gauges, map cases and thermos bottles.
The most distinctive feature of the Blériot No. XII, which was the first aeroplane to carry three passengers, was the long vertical keel, shaped like the fin of a fish at the top of the framework. The direction rudder was at the rear of this keel, while the elevation rudder was at the rear and a little below it. Immediately below the direction rudder was a small horizontal plane about the size of the elevation rudder which helped to maintain a fore and aft stability.
Then there was the famous Blériot aerobus which would carry 8 to 10 people. The machine was very large, the wings having a spread of 39 feet and a total area of 430 square feet. It was driven by a 100-horsepower Gnome motor and a propeller 10 feet in diameter, which was placed at the rear of the main plane. Thus the propeller drove the machine through the air from the rear instead of pulling it from the front as do the tractor propellers on most of the Blériot monoplanes. The passengers were seated underneath the main plane on the framework which extended out to the rear. The tail terminated in the vertical direction rudder and a large stationary horizontal surface which gave the necessary front-to-rear stability. The elevating plane of this type was placed out in front.
THE FLYING BOAT STARTING
The latest aeroplane is here seen cutting through the water preparatory to ascending into the air.