Ever since Marty McFly arrived in 2015 in "Back to the Future Part II" and discovered a levitating skateboard, people have tried to make one for real.

But the film's prediction, made in 1989, never quite came true.

Although so-called hoverboards have created quite a public splash this Christmas they do not really count.

They use a wheel (or wheels) to do their "hovering," with fancy electronics and stabilizers keeping them upright.

A few boards that really do hover, employing magnets for the task, have been demonstrated—but these work only over appropriate metal surfaces.

Various lash-ups, including one powered by four leaf-blowers that seems more hovercraft than hoverboard, have also appeared.

Film of hoverboarders gliding across a car park in Los Angeles turned out to be an elaborate YouTube hoax.

As 2015 turns into 2016, however, something resembling the real thing is going on sale.

The ArcaBoard (pictured above) does, admittedly, look like a giant iPhone case rather than a skateboard.

But it truly does hover.

It is 57 inches wide x 30 inches across (145cm x 76cm), is built from composite materials, and contains 36 high-powered electric ducted fans of the type used to fly model jet airplanes.

The fans are run by a pack of 72 lithium-polymer batteries, which provide just over 200 kilowatts of power.

That, the manufacturers claim, is sufficient to lift and carry someone weighing 180 lbs. (82kg).

In the ArcaBoard's current configuration it can do this for six minutes.

A beefed-up version is able to lift heavier people, but its flight duration drops to three minutes.

The ArcaBoard has been developed by ARCA Space, a Romanian aerospace company founded in 1999 that recently moved its headquarters to Las Cruces, New Mexico.

The firm has built a number of rockets and high-altitude drones, and has worked with the European Space Agency.

The hoverboard arose from a discussion among the firm's engineers about whether such a machine was possible, says Dragos Muresan, one of ARCA Space’s vice-presidents.

They built a prototype and successfully rode on it.

As enthusiasm for the idea grew, the company decided to put the device into production.

The first hoverboards should be delivered in April.  

The rider steers the board by shifting his body weight to provide yaw, but a built-in stabilization system makes things easier.

This uses a gyroscope and an accelerometer, connected to a computer, to keep the board level.

It adjusts the thrust of individual fans in order to control the other degrees of freedom of movement, pitch, and roll.

A proximity sensor on the board's underside ensures it stays 11.8 inches (30cm) above the ground and a speed-limiter keeps its rate of progress below 12 mph (20kph).

Before adding such a hoverboard to next Christmas's wish-list, however, you will want to consider the price: $19,900, plus an extra $4,500 for a fast-charger that can top up the batteries in 35 minutes rather than the six hours it would otherwise take.

The gold-plated tag is hardly surprising, considering the hoverboard is made by rocket scientists using what they readily admit is pricey aerospace technology.

Nevertheless, they hope to get the price down.

The first mobile phones, after all, began as clunky, costly devices with limited performance.

Now they are cheap enough for billions to own one.

Imagine if (genuine) hoverboards went the same way.