Egan Airships, the company formed by twin brothers James and Joel Egan, debuted their Plimp at the InterDrone exposition earlier this month. The first model is unmanned, making it a plane blimp drone, built within FAA limits. Because half of the weight of the vehicle is offset by the helium envelope (the big, blimp-like pouch on the top of the vehicle), the craft is larger than a typical drone: 28 feet long, and 7 feet in diameter. The Egan brothers first seriously explored the possibility of building such a craft in 1999, but materials at the time were too heavy to make it all work. In 2012, they revisited the idea, with an airframe made of carbon composites, which are light and strong enough to form working Plimps. The idea for Plimp gestated long before then.