35° THE CONQUEST OF THE AIR. 



ing- the balloon ascend and descend. If the balloonist wishes to 

 rise, air is pumped into the ballonet near the tail and squeezed 

 out of the one near the prow. The latter becomes thereby lighter, 

 the former, heavier, so that the balloon is placed under an angle, 

 \vith its nose in the air. As the motion takes place in the direc- 

 tion of the axis, the ship must rise, especially as the wind now 

 catches the underside of the ship. The re\erse takes place when 

 the ship is to descend or land. Air is then pumped into the 

 ballonet near the prow and squeezed out of the one near the 

 stern. On account of the somewhat sluggish action of filling 

 and emptying the ballonets, Parseval added a 40 kg. weight 

 running on ropes by means of rollers, which may be moved on 

 either side of the centre of gravity. 



In the 1910 type of sporting balloon, the ascending and 

 descending is accomplished entirely by means of elevating planes 

 placed under the prow. The lateral steering apparatus consists 

 of a rudder having an area of 8 square-metres joined to a vertical 

 stability plane of 20 square-metres. In order to prevent oscil- 

 lation round the horizontal cross axis, and tilting, damping- planes 

 of 18 square-metres surface are employed near the tail. These 

 consist of square-shaped fabrics fixed by ropes to steel tubes. 

 The fabrics are arranged in a manner so as to form air cushions, 

 by carrying in the middle a wind catcher. For rapidly emptying 

 the balloon, 4 ripping gores are provided to each ship. 



Very ingenious is the way in which the car or gondola of the 

 Parseval ship is fixed. In order to prevent the ropes which carry 

 the gondola from indenting the balloon, very long ropes have to 

 be employed. This lowers the centre of gravity to a very great 

 extent and thus increases the danger of tilting. Parseval pre- 

 vents this by fixing his gondola moveably on ropes and rollers. 

 Suppose the motor is set g^oing. It then moves the cage forward 

 and consequently pulls the ship along. As the latter receives the 

 greater part of the wind pressure, it will tend to rise, and the 

 result would be pitching. In the Parseval ship, as the gondola 

 moves forward, it slides along the ropes and therebv moves the 

 centre of gravity forward, which places the forward ropes under 

 tension and keeps the nose of the ship horizontal. 



Noteworthy also is the construction of the propellor blades. 

 They are also non-rigid, and consist of cloth fixed to a steel chain 

 weighted by cross steel bars. When the motor is not in action, 

 the blades hang limply downwards. As the speed increases, the 

 centrifugal force of the steel chain and rods stiffens the blades. 

 Weight is considerably reduced by the employment of these 

 blades. 



Parseval II. had the following dimensions : — 59 metres long, 

 4,000 cubic metres contents, 114 H.P. motor. The 1910 sporting 

 ship is 39 metres long, 8 metres largest diameter. The covering 

 consists of a double cotton fabric which will stand a pressure of a 

 ton on the square metre and weighs only 300 grammes per square 

 metre. The gores are placed horizontally, which improves the 

 appearance and reduces the skin resistance. Only one ballonet is 

 used, placed in the middle, the ascending and descending being- 

 accomplished with planes. 



