A demo of a drone that carries passengers – or as some cynics call it, a helicopter – had to be cancelled because of light rain. The makers say the problem is only with the demo model and the real thing will cope with poor weather.

The SureFly can carry two passengers and in its finished form will work autonomously, assuming you can find somebody willing to get into an unpiloted flying vehicle. The makers won a race against time to get it approved by regulators, ready to demo at an airfield near CES in Nevada.

Unfortunately the rain – which a BBC source described as “sprinkling very softly” – was enough to ground the vehicle. The fuselage hadn’t been waterproofed in the demo model, meaning the rain might have caused problems with both the rotor blades and the electrical system.

To be fair to the makers, Vegas has an average of just one centimeter of precipitation across all of January, so if they were in a rush it might have seemed a reasonable gamble that the demo would be on a dry day.

While the autonomous version is some way off, the key selling point of the SureFly right now is that the small size and limited range makes it considerably cheaper than most full-scale helicopter at $200,000. It can cover a maximum of 70 miles during the one hour of flight time from a full tank of gasoline. There’s also a pair of back-up batteries that give five minutes power for an emergency landing if the gas generator fails.