The first Lebaudy was pointed at the rear, which is generally admitted to be the proper shape for the least resistance, but to maintain stability it was found necessary to put a horizontal and vertical plane there, so that it had to be made an ellipsoid of revolution to give attachment for these planes.
The ballonet for air had a capacity of 22,958 cubic feet or about 1/5 of the total volume. This is calculated to permit reaching a height of about one mile and to be able to return to the earth, keeping the gas bag always rigid. To descend from a height of one mile, gas would be released by the valve, then air pumped into the ballonet to keep the gas bag rigid, these two operations being carried on alternately. On reaching the ground from the height of one mile, the air would be at the middle of the lower part of the gas bag and would not entirely fill the ballonet. To prevent the air from rolling from one end to the other when the air ship pitches, thus producing instability, the ballonet was divided into three compartments by impermeable cloth partitions. Numerous small holes were pierced in these partitions, through which the air finally reached the two end compartments.
In September, 1907, the Patrie was enlarged by 17,660 cubic feet by the addition of a cylindrical section at the maximum diameter, increasing the length but not the maximum diameter.
The Gas Bag.—The gas bag is cut in panels; the material is a rubber cloth made by the Continental Tire Company at Hanover, Germany. It consists of four layers arranged as follows:
| Weight oz. per square yard. | |
|---|---|
| a. Outer layer of cotton cloth covered with lead chromate | 2.5 |
| b. Layer of vulcanized rubber | 2.5 |
| c. Layer of cotton cloth | 2.5 |
| d. Inner layer of vulcanized rubber | 2.21 |
| ——— | |
| Total weight | 9.71 |
A strip of this cloth one foot wide tears at a tension of about 934 pounds. A pressure of about one inch of water can be maintained in the gas bag without danger. The lead chromate on the outside is to prevent the entrance of the actinic rays of the sun, which would cause the rubber to deteriorate. The heavy layer of rubber is to prevent the leaking of the gas. The inner layer of rubber is merely to prevent deterioration of the cloth by impurities in the gas. This material has the warp of the two layers of cotton cloth running in the same direction and is called straight thread. The material in the ballonet weighs only about 7¾ ounces per square yard, and has a strength of about 336 pounds per running foot. When the Patrie was enlarged in September, 1907, the specifications of the material allowed a maximum weight of 10 ounces per square yard, a minimum strength of 907 pounds per running foot, and a loss of 5.1 cubic inches of hydrogen per square yard in twenty-four hours at a pressure of 1.18 inches of water. Bands of cloth are pasted over the seams inside and out with a solution of rubber to prevent leaking through the stitches.
Suspension.—One of the characteristics of the Patrie is the “short” suspension. The weight of the car is distributed over only about 70 feet of the length of the gas bag. To do this, an elliptical-shaped frame of nickel-steel tubes is attached to the bottom of the gas bag; steel cables run from this down to the car. A small hemp net is attached to the gas bag by means of short wooden cross-pieces, or toggles, which are let into holes in a strong canvas band which is sewed directly on the gas bag. The metal frame, or platform, is attached to this net by means of toggles, so that it can be quickly removed in dismounting the air ship for transportation. The frame can also be taken apart, 28 steel cables about 0.2 inches in diameter run from the frame down to the car, and are arranged in triangles. Due to the impossibility of deforming a triangle, rigidity is maintained between the car and gas bag.
The objection to the “short” suspension of the Patrie is the deformation of the gas bag. A distinct curve can be seen in the middle.
The Car.—The car is made of nickel-steel tubes (12 per cent nickel). This metal gives the greatest strength for minimum weight. The car is boat-shaped, about 16 feet long, about 5 feet wide and 2½ feet high. About 11 feet separate the car from the gas bag. To prevent any chance of the fire from the engine communicating with the hydrogen, the steel framework under the gas bag is covered with a noncombustible material.
The pilot stands at the front of the car, the engine is in the middle, the engineer at the rear. Provision is made for mounting a telephotographic apparatus, and for a 100-candle-power acetylene searchlight. A strong pyramidal structure of steel is built under the car, pointing downward. In landing the point comes to the ground first and this protects the car, and especially the propellers, from being damaged. The car is covered to reduce air resistance. It is so low, however, that part of the equipment and most of the bodies of those inside are exposed, so that the total resistance of the car is large.