What happens when you cross a blimp with a plane, and give it a few helicopter features? A lighter-than-air plimp-hybrid airship is born, according to a Seattle-based company looking for investors.

For $4 million plus overages (paid out over four years), investors can buy their own Model J — a 169-foot-long (51 meters) aircraft that can carry up to 10 people (eight passengers and two pilots), or about 2,000 lbs. (907 kilograms) through the air, thanks to its helium-filled blimp-like body, gas-electric hybrid engines and rotational wings with propellers.

But don’t call it a plimp outright. That word is trademarked and meant to be used as an adjective, said James Egan, a Seattle-based attorney who is the CEO of Egan Airships, maker of the plimp-hybrid aircraft.

The idea came to Egan in childhood, as he was playing with helium balloons and balsa-wood gliders. He noticed that these wooden gliders had a slower descent when he tied helium balloons to the planes’ wings and tails. “I became convinced there could be another form of aircraft if only you could put wings on a partial-lift balloon,” Egan told Live Science.

He kept his eye on emerging technologies, such as the Boeing 787 Dreamliner plane, which uses lightweight carbon-fiber composites to make aircraft lighter and more fuel-efficient. Finally, he and his twin brother, Joel, approached Daniel Raymer, an engineer who agreed to take their concept of a half-helium-filled aircraft and turn it into a flyable design.

The helium in the blimp part of the plimp-hybrid aircraft is key, Egan said. “That decreases your unpowered descent rate to that of a parachutist,” he said. “You start with a design safety feature that no other aircraft has, which places you safely back on the ground if, for some reason, the engines fail.”

The plimp-hybrid airship is actually faster and safer than a blimp, which has to offgas during unpowered descent, Egan said. The newly designed airships are also different than the Hindenburg — the airship that met a fiery end when its lighter-than-air hydrogen gas leaked and mixed with oxygen, making a flammable mixture that quickly ignited. (In contrast, the plimp aircraft uses helium, which isn’t flammable.)