Nearly five decades before the Wright Flyer made its first flight, Henri Giffard had flown 24 km in France with his steam-engine powered airship. Since then airships have risen to its ultimate glory and have also seen a vicious downfall. The end of 20th century has rekindled interest in airship due to their efficiency and ability to stay afloat in the air for prolonged duration. I do not believe that airships can replace the conventional heavier-than-air aircraft. However, they are an ideal platform for applications which demand high endurance such as remote sensing, weather monitoring, surveillance and advertising to name a few.
One of the primary challenges in airship operation is its control. Airship dynamics are sluggish and take longer to respond to the control input from the user. Just like a balloon, it is susceptible to ambient wind conditions making airships difficult to maneuver. Unlike in heavier-than-air aircraft, it is difficult to maintain a desired heading angle in airships as they tend to be laterally unstable. This is why it is essential to have a closed loop control for maintaining the directional heading of the airship.
I had recently developed an airship with enhanced stability using the PlutoX Aerial Robotics Kit. Programming on the PlutoX platform was really easy, due to the fact that library already has pre-programmed APIs for commonly used tools like attitude estimation. I spent merely 3 hours in writing the PID control law for altitude hold, pitch regulation and heading stabilization. The PlutoX controller has inbuilt MOSFET based motor drivers, which could be used to power upto 8 motors. The 600mAh LiPo battery typically lasts about 10~12 minutes for a quadrotor. With this airship, the endurance was stretched to 40 minutes with the same battery.