Easy rider

Automotive technology specialist Prodrive is developing a narrow, fully enclosed vehicle with the banking action of a motorbike, which the company claims could be the answer to modern traffic congestion.

The two-seat vehicle, named Naro, will allow riders to pick their way through all but the densest traffic within a given road space, according to Damian Harty, Prodrive’s chief dynamics engineer.

At a maximum width of 1m, Naro offers the main advantages of a motorbike – being able to filter through cars waiting at traffic lights or stuck in jams – without the greater danger and discomfort of riders being more exposed to the elements.

But unlike other novel vehicles, such as the much maligned Sinclair C5 (pictured), Naro is also 2.2m tall, improving riders’ ability to see and plan in traffic, as their eyeline is 1.8m, compared to 1.6m in a Ford Galaxy and 1.3m in a typical car.

‘The biggest criticism of the Sinclair C5 was that it was very low, so people felt scared. So if you are going to make a vehicle like this, which is weird anyway, it has got to be tall,’ said Harty.

To prevent its height causing it to topple over, Naro is capable of leaning into turns. It does this without the use of expensive equipment such as hydraulics to force it to lean, but using the laws of physics in the same way that motorbikes lean into corners. ‘Our priority was robustness, which led us down the free-leaning route. Once on the move it behaves exactly like a motorbike or bike,’ said Harty.

Naro is fitted with a roll-brake, which switches off this ability to lean when pulled by the rider as the vehicle slows to a halt. This ensures that the vehicle is stable when it is stationary, and when the brakes are applied. The roll-brake also ensures that if there is a problem with the vehicle’s systems, it will not simply fall over.

One of the problems with such vehicles is that people unaccustomed to riding motorbikes have difficulty steering at high speeds, said Harty. ‘When you are travelling at speeds you have to steer very slightly the wrong way to initiate a turn, then you turn the right way. But if people aren’t thinking about it they won’t do that,’ he said.

So Naro uses a steer-by-wire system, similar in concept to BMW’s active steering, to assist. As the rider moves the aircraft-style control yoke, the steer-by-wire system and roll-brake decide between themselves how the vehicle should move.

Unlike some other vehicles of this type being developed, such as the CLEVER vehicle, Naro has four wheels. ‘We did toy with the idea of three wheels, as you get an immediate weight saving, but whenever you say the word three followed by wheels people think of Del Trotter’s van. So the reality is that if you are going to make a vehicle, it has got to have four wheels,’ said Harty. Having four wheels also improves the vehicle’s stability and braking, he said.

The vehicle offers significant environmental benefits as a result of its low weight. ‘There are huge environmental penalties from using a 1250kg car to move a person who weighs 80kg,’ said Harty.

Motorbikes weigh around 250kg, and while bikes tend to be less aerodynamic than cars Naro will be completely enclosed, mitigating this problem. As a result the vehicle will offer considerable improvements in fuel economy, reducing carbon dioxide emissions. In fact, there is no reason why a target of one litre per 100km should not be possible, said Harty.

As the vehicle is smaller and lighter, it also requires less power for propulsion, at around 15-20kW. This would put it within the power range of a fuel cell stack, said Harty.

The company is working with industrial partners on the project, although Harty declined to name them. The team is developing a prototype vehicle, using a scooter engine for simplicity, and has carried out mathematical modelling. ‘What I like about this is that we are not using anything that hasn’t been used before – it is a novel combination of existing technologies,’ he said.

Once commercialised, the vehicle would be likely to cost around £4,500-£5,000.

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