airship.com

Airships must fly at or near neutral buoyancy if they are to carry a heavy load, loiter for extended periods of time, and burn small quantities of fuel while traveling strategic distances. For fixed wing aircraft as well as airships, each incremental increase in speed requires that power increase asymptotically.

Airship Lift Is Volumetric, Not Aerodynamic – Every time helium volume is  doubled, gross lift of the airship is tripled. It follows that airships must be built in large sizes in order to contain enough buoyant lifting gas (helium) to carry an operationally useful load and be economically efficient.

Airships should be built in modular pressure sections which absorb and compensate for overall structural stresses and bending moments, lengthening but not widening the profile to increase helium volume. The summary reason for a high fineness ratio airship (ratio of width, or cross section to length) has to do with cost and efficiency.

A high fineness ratio airship with a fineness ratio in excess of 8:1 provides a minimal cross section and minimal capital and operating cost when measured versus payload capability. Because it uses helium lift and propulsive power efficiently and properly, it is at least 4 times more power and cost efficient than a lower fineness ratio airship (i.e. a blimp) and approximately 8 times more power and cost efficient than any hybrid airship design. Correct Lighter Than Air (LTA) design principles apply to airships intended for use as low cost transportation platforms as well as to airships that are intended for use as persistent ISR platforms.