Kraft was a prolific inventor, with roughly ninety patents
assigned to Goodyear or The General Tire Company.
This is one of his few patents related to Lighter-than-air.
Neither this earlier "pony blimp" nor Kraft's invention have
a rudder on top of the envelope. But notice the wide separation
between its envelope and the supported open car.
“Dirigible aircraft of the non-rigid type as heretofore
constructed, are generally provided with control or pilot cars
suspended by means of a number of wires secured to finger
patches distributed over considerable area of the lower surface
of the envelope; or by numerous suspension lines disposed
circumferentially over top and sides of the envelope. The
number of wires necessary to properly suspend loads to be
carried present an intricate network of suspension members
and the control car must be spaced a considerable distance
from the lower surface of the envelope in order to reduce the
stresses tending to buckle the aircraft upwardly adjacent to the
middle portion. In case gas pressure in the envelope becomes
low, there is a strong tendency for its shape to become bowed
at the central portion because of the forces exerted by the
suspension wires pulling from the ends of the aircraft toward
its center. Also the greater the distance between the envelope
of the aircraft and the control car, the greater will be the
impediment to speed, and the more will be the difficulty
encountered in steering.”
NOTE: This is one of Kraft's few patents related to Lighter-than-air.
In it he emphasizes three key innovations:
To simplify construction and rigging;
To reduce drag; and
To improve steering.
N.B. Kraft points out that his invention is particularly useful for the
small pressure airships known as "Pony Blimps", but that it would
also be useful for large airships.
The USPTO only assigned one of several applicable classifications.