Fig. 11. Car of La Republique
The pisciform shape of the first Clement-Bayard was retained but given more taper, the dimensions being 248.6 feet overall by 42.9 greatest diameter, this being but a short distance back of the bow. This gives it a ratio of length to diameter of 5.76. The gas balloonet stabilizers were eliminated altogether, Fig. 12. The total gas capacity is approximately 80,000 cubic feet. Like all French dirigibles it is of the true flexible type, the only rigid construction being that of the framework of the car itself. To the latter are attached all rudders and stabilizing devices, instead of making them a part of the envelope as formerly. The latter is made of continental rubber cloth.
Fig. 12. Clement-Bayard II, French Dirigible
Light steel and aluminum tubing are employed in the construction of the frame supplemented by numerous piano-wire stays. This frame extends almost the entire length of the envelope and carries at its rear end a cellular, or box-kite, type of stabilizing rudder, instead of the former gas balloonets employed on the Clement-Bayard I, Fig. 13. This cellular rudder is in two parts, consisting of two units of four cells each, the two groups being joined at the top, with a space between them. In addition to acting as a stabilizer, this is also the direction rudder, its leverage being increased by making the end planes somewhat larger than the partitions of the cells. Between the cellular stabilizing rudder and the envelope is placed the horizontal rudder for ascending or descending. In the illustration this appears to be a flag, but it is in reality a long rectangular plane, which may be tilted on its longitudinal axis, the latter being at right angles to that of the balloon. There are two air balloonets of about one-third the total capacity of the balloon itself, and they are designed to be inflated by large aluminum centrifugal blowers driven from the main engines themselves.
Fig. 13. Clement-Bayard I
There are two motors, each of 125 horsepower, both being of the same conventional design, i.e., four cylinder four cycle vertical water cooled. In fact, they are merely light automobile motors. The cylinders have separate copper water jackets and the motors themselves are muffled, which is a departure from the usual custom. Each drives a separate propeller carried on top of the main frame through bevel gearing.
The Clement-Bayard II made itself famous by its rapid and successful flight from the suburbs of Paris across the Channel to London, in October, 1910.
Astra-Torres. In reviewing the specifications of any of the big dirigibles, the observer cannot fail to be struck by the excessive amount of power necessary to drive them at speeds which are lower than the minimum, or landing speeds, of many aeroplanes. When a speed of 45 miles per hour was first reached by a dirigible, it was acclaimed as a great feat. But this comparatively moderate rate of travel was surpassed only by increasing the number of motors and their horsepower until the fuel consumption became exceedingly high. This necessitated the carrying of a great weight of fuel and cut down correspondingly the useful load that the dirigible was capable of lifting as well as restricted its radius of flight at full speed. Until aerodynamic research had demonstrated the contrary, the necessity for such a tremendous amount of power was considered necessary to overcome the head resistance of the balloon itself. Research brought out in a striking manner how great a proportion of the total head resistance of an aeroplane was due to the struts and bracing wires. In the construction of the different types of airships illustrated, it will be noted that the gear provided for suspending the car or cars below the balloon requires a great number of cables. Later developments showed that by eliminating the great amount of head resistance caused by these numerous surfaces, the speed of a dirigible could be increased by over 50 per cent with the same amount of power.