How Akron's structure balanced strength and weight

Akron's heavier, self-supporting Warren-truss frames replaced the lighter wire-braced structure of traditional Zeppelins. The extra structural weight reduced the risk of the inflight breakups suffered by earlier American airships. Externally mounted cantilever fins were intended to give greater control than the traditional Zeppelin arrangement. Three longitudinal keels strengthened the hull and provided walkways. The lower keels carried fuel and ballast tanks, controls, wiring, and eight engine rooms. Non-flammable helium allowed the engines to sit inside the hull, where crews could maintain them in flight. Shafts transmitted their power to external propellers.