The Motor.—The first Lebaudy had a 40-horse-power Daimler-Mercedes benzine motor. The Patrie was driven by a 60 to 70-horse-power 4-cylinder Panhard and Levassor benzine motor, making 1,000 r. p. m.

The Propellers.—There are two steel propellers 8½ feet in diameter (two blades each) placed at each side of the engine, this giving the shortest and most economical transmission. To avoid any tendency to twist the car, the propellers turn in opposite directions. They are “high speed,” making 1,000 to 1,200 r. p. m.

The gasoline tank is placed under the car inside the pyramidal frame. The gasoline is forced up to the motor by air compression. The exhaust is under the rear of the car pointing down and is covered with a metal gauze to prevent flames coming out. The fan which drives the air into the ballonet is run by the motor, but a dynamo is also provided so that the fan can always be kept running even if the motor stops. This is very essential as the pressure must be maintained inside the gas bag so that the latter will remain rigid and keep its form. There are five valves in all, part automatic and part both automatic and also controlled from the car with cords. The valves in the ballonet open automatically at less pressure than the gas valves, so that when the gas expands all the air is driven out of the ballonet before there is any loss of gas. The ballonet valves open at a pressure of about O.78 inches of water, the gas valves at about 2 inches.

Stability.—Vertical stability is maintained by means of fixed horizontal planes. One having a surface of 150 square feet is attached at the rear of the gas bag and due to its distance from the center of gravity is very efficient. The elliptical frame attached under the gas bag has an area of 1,055 square feet, but due to its proximity to the center of gravity, has little effect on the stability. Just behind the elliptical frame is an arrangement similar to the feathering of an arrow. It consists of a horizontal plane of 150 square feet, and a vertical plane of 113 square feet. To maintain horizontal stability, that is, to enable the air ship to move forward in a straight line without veering to the sides, fixed vertical planes are used. One runs from the center to the rear of the elliptical frame and has an area of 108 square feet.

In addition to the vertical surface of 113 square feet at the rear of the elliptical frame, there is a fixed plane of 150 square feet at the rear of the gas bag. To fasten the two perpendicular planes at the rear of this gas bag, cloth flaps are sewed directly on the gas bag. Nickel-steel tubes are placed in the flaps, which are then laced over the tubes. With these tubes as a base, a light tube and wire framework is attached and waterproof cloth laced on this framework. Additional braces run from one surface to the other and from each surface to the gas bag. The rudder is at the rear under the gas bag. It has about 150 square feet and is balanced.

A movable horizontal plane near the center of gravity, above the car, is used to produce rising or descending motion, or to prevent an involuntary rising or falling of the air ship due to expansion or contraction of the gas or to other causes. After the adoption of this movable horizontal plane, the loss of gas and ballast was reduced to a minimum. Ballast is carried in 10- and 20-pound sandbags. A pipe runs through the bottom of the car from which the ballast is thrown.

There are two long guide-ropes, one attached at the front of the elliptical frame and the other on the car. On landing, the one in front is seized first so as to hold the air ship with the head to the wind. The motor may then be stopped and the descent made by pulling down on both guide-ropes. A heavy rope 22 feet long, weighing 110 pounds, is attached at the end of a 164-foot guide-rope. This can be dropped out on landing to prevent coming to the ground too rapidly. The equipment of the car includes a “siren” speaking trumpet, carrier pigeons, iron pins and a rope for anchoring the air ship, reserve supply of fuel and water, and fire extinguisher.

After being enlarged in September, 1907, the Patrie made a number of long trips at an altitude of 2,500 to 3,000 feet. In November, 1907, she went from Paris to Verdun, near the German frontier, a distance of about 175 miles, in about 7 hours, carrying four persons. This trip was made in a light wind blowing from the northeast. Her course was east, so that the wind was unfavorable. On Friday, November 20, 1907, during a flight near Verdun, the motor stopped due to difficulty with the carburetor. The air ship drifted with the wind to a village about 10 miles away, where she was safely landed. The carburetor was repaired on the 20th. Soon after, a strong wind came up and tore loose some of the iron pickets with which it was anchored. This allowed the air ship to swing broadside to the wind; it then tilted over on the side far enough to let some of the ballast bags fall out. The 150 or 200 soldiers who were holding the ropes were pulled along the ground until directed by the officer in charge to let go. After being released, it rose and was carried by the wind across the north of France, the English Channel and into the north of Ireland. It struck the earth there, breaking off one of the propellers, and then drifted to sea.

The République

This is the latest of the French military dirigible balloons, and differs but slightly from its predecessor, the Patrie. The volume has been increased by about 2,000 cubic feet. The length has been reduced to 200 feet and the maximum diameter increased to 35½ feet. The shape of the gas bag accounts for the 2,000 additional cubic feet of volume. The motor and propeller are as in the Patrie. The total lifting capacity is 9,000 pounds, of which 2,700 pounds are available for passengers, fuel, ballast, instruments, etc. Its best performance was a 125-mile flight made in 6½ hours against an unfavorable wind.