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therefore no pressure is required in the gas…chamber to maintain its shape；
it will not be readily vulnerable to projectiles。 But the Count did not
foresee that the very 〃frightfulness〃 of his engine of war would engender
counter…destructives。 In a later chapter an account will be given of the
manner in which Zeppelin attacks upon these islands were gradually
beaten off by the combined efforts of anti…aircraft guns and aeroplanes。 To
the latter； and the intrepid pilots and fighters； is due the chief credit for the
final overthrow of the Zeppelin as a weapon of offence。 Both the British
and French airmen in various brilliant sallies succeeded in gradually
breaking up and destroying this Armada of the Air； and the Zeppelin was
forced back to the one line of work in which it has proved a success； viz。；
scouting for the German fleet in the few timid sallies it has made from
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home ports。
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CHAPTER XI The Semi…rigid Air…ship
Modern air…ships are of three general types： RIGID； SEMI…RIGID； and
NON…RIGID。 These differ from one another； as the names suggest； in the
important feature； the RIGIDITY； NON…RIGIDITY； and PARTIAL
RIGIDITY of the gas envelope。
Hitherto we have discussed the RIGID type of vessel with which the
name of Count Zeppelin is so closely associated。 This vessel is； as we
have seen； not dependent for its form on the gas…bag； but is maintained in
permanent shape by means of an aluminium framework。 A serious
disadvantage to this type of craft is that it lacks the portability necessary
for military purposes。 It is true that the vessel can be taken to pieces； but
not quickly。 The NON…RIGID type； on the other hand； can be quickly
deflated； and the parts of the car and engine can be readily transported to
the nearest balloon station when occasion requires。
In the SEMI…RIGID type of air…ship the vessel is dependent for its
form partly on its framework and partly on the form of the gas envelope。
The under side of the balloon consists of a flat rigid framework； to which
the planes are attached； and from which the car； the engine； and propeller
are suspended。
As the rigid type of dirigible is chiefly advocated in Germany； so the
semi…rigid craft is most popular in France。 The famous Lebaudy air…ships
are good types of semi…rigid vessels。 These were designed for the firm of
Lebaudy Freres by the well…known French engineer M。 Henri Julliot。
In November； 1902； M。 Julliot and M。 Surcouf completed an air…ship
for M。 Lebaudy which attained a speed of nearly 25 miles an hour。 The
craft； which was named Lebaudy I； made many successful voyages； and in
1905 M。 Lebaudy offered a second vessel； Lebaudy II； to the French
Minister of War； who accepted it for the French nation； and afterwards
decided to order another dirigible； La Patrie； of the same type。 Disaster；
however； followed these air…ships。 Lebaudy I was torn from its anchorage
during a heavy gale in 1906； and was completely wrecked。 La Patrie； after
travelling in 1907 from Paris to Verdun； in seven hours； was； a few days
later； caught in a gale； and the pilot was forced to descend。 The wind；
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however； was so strong that 200 soldiers were unable to hold down the
unwieldy craft； and it was torn from their hands。 It sailed away in a north…
westerly direction over the Channel into England； and ultimately
disappeared into the North Sea； where it was subsequently discovered
some days after the accident。
Notwithstanding these disasters the French military authorities ordered
another craft of the same type； which was afterwards named the
Republique。 This vessel made a magnificent flight of six and a half hours
in 1908； and it was considered to have quite exceptional features； which
eclipsed the previous efforts of Messrs。 Julliot and Lebaudy。
Unfortunately； however； this vessel was wrecked in a very terrible
manner。 While out cruising with a crew of four officers one of the
propeller blades was suddenly fractured； and； flying off with immense
force； it entered the balloon； which it ripped to pieces。 The majestic craft
crumpled up and crashed to the ground； killing its crew in its fall。
In the illustration facing p。 17； of a Lebaudy air…ship； we have a good
type of the semi…rigid craft。 In shape it somewhat resembles an enormous
porpoise； with a sharply…pointed nose。 The whole vessel is not as
symmetrical as a Zeppelin dirigible； but its inventors claim that the sharp
prow facilitates the steady displace ment of the air during flight。 The stern
is rounded so as to provide sufficient support for the rear planes。
Two propellers are employed； and are fixed outside the car； one on
each side； and almost in the centre of the vessel。 This is a some what
unusual arrangement。 Some inventors； such as Mr。 Spencer； place the
propellers at the prow； so that the air…ship is DRAWN along； others prefer
the propeller at the stern； whereby the craft is PUSHED along； but M。
Julliot chose the central position； because there the disturbance of the air is
smallest。
The body of the balloon is not quite round； for the lower part is
flattened and rests on a rigid frame from which the car is suspended。 The
balloon is divided into three compartments； so that the heavier air does not
move to one part of the balloon when it is tilted。
In the picture there is shown the petrol storage…tank； which is
suspended immediately under the rear horizontal plane； where it is out of
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danger of ignition from the hot engine placed in the car。
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C