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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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THE MASTERY OF THE AIR
danger of ignition from the hot engine placed in the car。
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CHAPTER XII A Non…rigid Balloon
Hitherto we have described the rigid and semi…rigid types of air…ships。
We have seen that the former maintains its shape without assistance from
the gas which inflates its envelope and supplies the lifting power； while
the latter； as its name implies； is dependent for its form partly on the flat
rigid framework to which the car is attached； and partly on the gas
balloon。
We have now to turn our attention to that type of craft known as a
NON…RIGID BALLOON。 This vessel relies for its form ENTIRELY upon
the pressure of the gas； which keeps the envelope distended with sufficient
tautness to enable it to be driven through the air at a considerable speed。
It will at once be seen that the safety of a vessel of this type depends
on the maintenance of the gas pressure； and that it is liable to be quickly
put out of action if the envelope becomes torn。 Such an occurrence is quite
possible in war。 A well…directed shell which pierced the balloon would
undoubtedly be disastrous to air…ship and crew。 For this reason the non…
rigid balloon does not appear to have much future value as a fighting ship。
But； as great speed can be obtained from it； it seems especially suited for
short overland voyages； either for sporting or commercial purposes。 One
of its greatest advantages is that it can be easily deflated； and can be
packed away into a very small compass。
A good type of the non…rigid air…ship is that built by Major Von
Parseval； which is named after its inventor。 The Parseval has been
described as 〃a marvel of modern aeronautical construction〃； and also as
〃one of the most perfect expressions of modern aeronautics； not only on
account of its design； but owing to its striking efficiency。
The balloon has the elongated form； rounded or pointed at one end； or
both ends； which is common to most air…ships。 The envelope is composed
of a rubber…texture fabric； and externally it is painted yellow； so that the
chemical properties of the sun's rays may not injure the rubber。 There are
two smaller interior balloons； or COMPENSATORS； into which can be
pumped air by means of a mechanically…driven fan or ventilator； to make
up for contraction of the gas when descending or meeting a cooler
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atmosphere。 The compensators occupy about one…quarter of the whole
volume。
To secure the necessary inclination of the balloon while in flight； air
can be transferred from one of the compensators； say at the fore end of the
ship； into the ballonet in the aft part。 Suppose it is desired to incline the
bow of the craft upward； then the ventilating fan would DEFLATE the
fore ballonet and INFLATE the aft one； so that the latter； becoming
heavier； would lower the stern and raise the bow of the vessel。
Along each side of the envelope are seen strips to which the car
suspension…cords are attached。 To prevent these cords being jerked
asunder； by the rolling or pitching of the vessel； horizontal fins； each 172
square feet in area； are provided at each side of the rear end of the balloon。
In the past several serious accidents have been caused by the violent
pitching of the balloon when caught in a gale； and so severe have been the
stresses on the suspension cords that great damage has been done to the
envelope； and the aeronauts have been fortun