The proportion of the useful lift in a large rigid, that is the
lift available for fuel, crew, passengers, and merchandise, is
well over 50 per cent when compared with the gross lift. When the
accompanying table is studied it will be seen that with airships
of large capacity the available lift will be such that
considerable weights of merchandise or passengers can be carried.

Capacity in Gross Lift Length Diameter
cubic feet in tons in feet in feet
2,000,000 60.7 643 79
3,000,000 91.1 736 90.4
4,000,000 121.4 810 99.5
5,000,000 151.8 872 107.2
6,000,000 182.2 927 113.9
7,000,000 212.5 976 119.9
8,000,000 242.8 1,021 125.5
9,000,000 273.3 1,061 130.4
10,000,000 303.6 1,100 135.1


In airships of their present capacity, in order to obtain the
greatest amount of lift possible, lightness of construction has
been of paramount importance. With this object in view duralumin
has been used, and complicated girders built up to obtain
strength without increase of weight. In a large ship with a
considerable gain in lift, steel will probably be employed with a
simpler form of girder work. In that way cheapness of
construction will be effected together with increased rapidity of
output, and in addition the strength of the whole structure