Understanding the Difference Between Rigid Airships, Semi-Rigid Airships, and Blimps

Pathfinder 1,  LTA Research’s 406-foot-long proof-of-concept aircraft, is currently the only rigid airship flying today in 2026. For the first time since 1938, all three categories of airships are sharing the skies. The following outlines the differences between these three lighter-than-air vehicles and how their designs set them apart.

What is an Airship? 

Airship is the umbrella term that refers to all lighter-than-air aircraft that are steerable and have propulsion. Rigid airships, semi-rigid airships, and blimps are all types of airships. 

Rigid Airships

Rigid airships, classically known as Zeppelins or dirigibles, get their shape from an internal skeleton like the frame of a house. The internal structure allows rigid airships to be built at a much larger scale than their counterparts. Within this frame, multiple cells contain the lifting gas. For Pathfinder 1 and most modern airships, the lifting gas is non-flammable helium. Because lift increases drastically with size, the maximum payload of a rigid airship can also be much greater.

Blimps/Non-Rigid Airships

A blimp gets its shape from the internal pressure of its lifting gas, much like a balloon. With no internal structure, blimps tend to be the smallest of the three types of airships. These lighter-than-air vehicles are also the most cost-effective and the easiest to maintain. However, their lifting and operational capabilities are very limited. At LTA, we use blimps for pilot and crew training.

Semi-Rigid Airships 

The semi-rigid airship is a cross between a rigid airship and a blimp. It has a small structure running the length of the hull, but the rest of the aircraft’s shape is created by pressure from the lifting gas, like a blimp. The spine-like structure supports the distribution of weight from the gondola and engines across the vehicle. It’s a lesser-known fact that today’s Goodyear “blimps” are actually semi-rigid airships.

Understanding the structure of each type of airship is key to identifying the lighter-than-air vehicles you spot in the sky. This is the case whether you are looking at a blimp, semi-rigid, or rigid airship like Pathfinder 1.