The Blériot IV in the form of a bird, of which we spoke at length in No. 4 of the Bulletin of this year, does not appear to give good results, perhaps on account of its lack of stability, and Blériot instead of trying some modifications which might remedy such a grave fault, laid it aside and at once began the construction of a new type, No. V, adopting purely and simply the arrangement of the American, Langley, which offers a good stability (see Bulletin 11–12, November to December, 1905, pages 187 and 188).
The experiments, which were commenced a month ago, were first completely negative, because the 24 HP. motor would not turn the propeller, which was 1.80 m. in diameter and 1.40 m. pitch.
By advice of Captain Ferber, Blériot reduced the pitch of his propeller to 0.90 m., so that the motor could give all its force.
This modification was an important one for his aeroplane. From that moment every trial marked an advance. On July 12, he made a flight of 30 m., and the aviator was able to show that the lateral stability was perfect. On July 15, the trial was made against a wind of 6 miles an hour, but gave good results. He made a flight of 80 m., showing, however, that the hind part of the aeroplane was too heavy. In this flight he arose as high as a second story, and on landing the wheels and one propeller were somewhat damaged.
On July 24, repairs having been completed, a new trial was made. This time, in order to remedy the defect in the balance, Blériot had moved his seat forward about 80 cm. The correction was too great, for on that day the aeroplane, although the hind part arose, was not able to leave the ground. On July 27, after having mounted the seat on wheels as skiffs, Blériot resumed the trials and made a flight of 120 m., at first moving his seat back and then, after getting started, bringing it forward. Blériot had not provided this aeroplane with an elevating rudder, but, following the example of Lilienthal, changed the center of gravity of the apparatus by moving his own person, and after having established the proper angle remained immovable on his seat. In order to arise or descend, the aviator made use of the spark lever, thus varying the number of turns of the propeller.
During a second trial on the same day, having accidently reached the limit of the aviation field, Blériot, without allowing himself to be surprised and obliged to descend, decided to attempt a turn by maneuvering the steering rudder [p284] and to return again to the center of the field. With marvelous precision, the aeroplane began to describe a circle of about 200 m. radius, inclining as if on a banked track. Having finished the flight, he quickly regained his balance still in the direction of the wind, but on account of a slight movement of the aviator, the aeroplane fell to such an extent that he was obliged to land. He landed gently and without shock, rolling on his wheels.
On August 1, he made another flight of 100 m. in 612 seconds; and on the 6th, one of 265 m. with one interruption. While the attention of the pilot was distracted for a moment, the aeroplane, which was flying at a height of 2 or 3 m. above the ground, touched the soil with its sustaining wheels at the end of 122 m. and then immediately arising, covered the remaining 143 m. at a height of 12 m. Blériot, moving forward too quickly, caused the aeroplane to descend swiftly to the ground, and the shock broke the axle and the blades of the propeller were bent. In order to confirm this account, we reproduce what was said in the “Auto” of August 7, 1907.
“M. Blériot, continuing the trials of his aeroplane yesterday, surpassed the superb results which he had already obtained. The trial took place at 2 o’clock in the afternoon on the aviation field of Issy. After a sustained flight of about 122 m. at a height of 2 m., the aeroplane touched the ground, without stopping, however, and set out again almost immediately at a height of 12 m. and traversed about 143 m. M. Blériot, who for the time had no other means of balancing but by moving his body, then moved a little forward to stop the ascent. The aeroplane plunged forward, and in the fall the propeller was damaged and the axle broken.
“M. Blériot, whose courage as a sportsman equals his learning as an engineer, was fortunately uninjured. An inspection of the apparatus showed that one blade of the propeller was bent, which was sufficient to prevent the maneuver made by the aviator having its desired effect and contributed to the fall. The engine will be repaired without difficulty and the trials will be resumed Friday.”
On August 10, he made a flight of 80 m., but the motor was not in perfect order, so Blériot did not make other trials. He decided, however, to substitute definitely a 50 HP. motor for the 24 HP. motor with which he made all the experiments above reported, which were of a character to encourage the most sanguine expectations.