THERE is something of the 19th century about Eric Raymond. Devoted to making commercial solar-powered aircraft, he would have thrived in the Victorian heyday of the private inventor. Most fell by the wayside; their ideas outran their ability or their money. But the names of the successes—Morse, Dunlop, Bell, Diesel and even, to stretch the era into the early 20th century, the brothers Wright—have lived on.

Whether Mr Raymond will join their ranks remains to be seen. His latest effort, known as Sunseeker Duo, was taken out of its shed in June. It has yet to fly (as his website endearingly puts it: “Well, we couldn’t really roll it out, as the main gear is not finished, but here it is”). He has high hopes, however, that his solar plane soon will take to the air.

Like its predecessor prototypes, Sunseeker I (which once flew, in stages, right across North America) and Sunseeker II, Sunseeker Duo looks like what it is: a glider with a propeller and lots of solar cells to generate electricity on the upper surface of its wings.

The most obvious difference from the previous efforts are two seats in the cockpit. That should make it easier to sell if Mr Raymond is ever able to go into full-scale production. There are lots of other differences, as well, though—ones that Mr Raymond hopes will bring the day of production closer.

The Duo has a wingspan of 23 metres and a planned weight, when the main gear and any other missing equipment is on board, of 270kg. A 20kW electric motor will drive the propeller, but all of those watts will be needed only during take off and climbing. In level flight, at an altitude of 6,000 metres, the 5kW provided by the solar panels will be enough both to drive the propeller and to recharge the batteries.

One big difference between the Duo and its predecessors is that those batteries are lithium-polymer cells sitting in the wings, near the plane’s centre of gravity, and not nickel-cadmium ones scattered artfully around the airframe. Lithium-polymer cells are lighter.

The system will also run at a higher voltage—300V, up from 200V in Sunseeker II—in order to reduce transmission losses along the six metres of cables that carry power to the motor at the back, just above the rudder.

The Sunseeker project is still in many ways a sealing-wax-and-string operation. The lithium-polymer batteries, for example, were donated by Tian Yu, a Chinese businessman with whom Mr Raymond is collaborating on a non-solar electric plane. But one day, perhaps, the name of Raymond will be up there with the others. For who in their right mind would have believed in 1902 that a couple of bicycle-makers from Dayton, Ohio, would achieve immortal fame the following year?

Update 26 November 2012: The original version of this article said that the Sunseeker Duo's planned weight would be 470kg. That referred to the target weight with two passengers aboard. The correct, empty weight for the plane itself is 270kg. Apologies.