Type-D

(from Connaught Press Release)  A revolutionary concept in vehicle design and engineering was announced this morning (3 September) when the Connaught Motor Company revealed its first project – the Type-D sports coupé – at the Goodwood Revival meeting.

Featuring the first ever V10 hybrid engine, Connaught's Type-D beats mainstream manufacturers in the race to produce a high performance energy-efficient sports car. The stunning coupé will deliver 140mph, 0-60mph in 6.2s, 42mpg and genuine 2+2+ seating configuration, while still complying with ultra-low emissions targets set for 2010.

The brainchild of two ex-Jaguar consultant engineers, Tim Bishop and Tony Martindale, the Connaught Type-D has to date received almost half a million pounds worth of funding from the Energy Saving Trust and has no less than 17 patents pending on its ground-breaking technology.

The car was previewed at Goodwood's Revival meeting, a fitting venue to resurrect a famous name of 1950s automotive engineering, but the new Connaught Motor Company is no heritage-laden throw-back to past eras.

Connaught is the first virtual car company. It designs the car and manages the project, but out-sources the manufacturing to Derby-based partners EPM Technology, thereby ensuring relatively low start-up investment costs.

The ultra-lightweight construction helps to realise the ambitious fuel efficiency targets while the mid-front north-south mounted engine and rear-wheel drive configuration guarantees maximum driving pleasure without compromising rear space. The cleverly engineered convertible ‘Eclipse’ version will have electrically-powered stacking glass panels which disappear into the boot lid without loss of luggage space. The Type-D will be competitively priced starting at around £35,000.

"Our aim has been to build a car for the future while keeping the design and technology relatively simple," explains Tim Bishop, vehicle engineering director, "and to establish close links with our technology partners EPM Technology for the assembly and Coventry University on the styling side. We have met all our own development targets and are confident to gain five-star EuroNCAP crash test results and maximum score for pedestrian safety."

Powertrain: a study in energy efficiency

Connaught plays down the Type-D's hybrid drive, wishing to distance its sports coupé from existing hybrid cars with their utilitarian aura and earnest greenness. Market research has revealed that some potential buyers of pleasure machines are put off by the hybrid idea, thanks to inaccurate preconceptions of plugging the cars into the mains and thoughts of slow electric vehicles. Buyers with some technical understanding are more likely to appreciate the benefits, however, and in the longer term the Connaught will be seen as a pioneer in its field.

So for 'hybrid', read Connaught's alternative description: HigherBred. Think of the electric motor as a torque-assist system, a means to an end rather than an end in itself. First, though, the heart of the Type-D.

V10 power

The all-aluminium, ultra-compact, 2110cc V10 engine is packed with innovative features. The vee-angle is just 22.5 degrees, which makes the engine narrow and gives good balance with even firing intervals. The wet cylinder liners mate directly with the cylinder head, with no gasket, and other components are sealed with rubber where necessary.

The crankshaft is pressed together from 22 components, and fed into the block from one end. Its webs double as very large main-bearing journals, but the bearing surface is very slender to keep friction down. The pistons have ceramic crowns, to reduce the heat transfer to the block that would otherwise be the V10 configuration's biggest snag given a cylinder surface-to-volume ratio much higher than that of, say, a four-cylinder engine. Future developments could include V8 and V12 versions of the engine.

For a rapid warm-up and maximum efficiency, the cylinder head has its own water-cooling circuit. When the block needs to be cooled as well, an interconnecting valve opens to unite the cooling circuits, pumped by an electric water pump as required. There are two valves per cylinder, a single overhead camshaft per bank with bucket tappets and variable valve timing system, and a very high (13.5 to one) compression ratio. Cross-linking of opposite inlet ports produces pressure pulses to improve low-speed torque, and each cylinder has its own throttle valve.

The engine alone reaches its torque peak at 4000rpm, but with the electric motor assisting its efforts there's a flat torque curve of 144lb ft from 1000rpm right up to 6000rpm. That strong low-end pull is the secret of the Connaught's pace, delivering a pulling ability extraordinary for such a compact engine unit. Maximum combined power – 162bhp – arrives at 6000rpm.

Added electricity

The Lynch electric motor is attached to the crankshaft nose, via a variable gearing system designed to exploit the fact that an electric motor delivers its highest torque at its lowest speeds. The drive system ensures that the motor always runs at the best speed for the conditions. It's powered by, and recharges, a 48-volt electrical supply, which keeps current levels low and makes for quicker recharging. There's also a capacitive and fast charging storage system to respond instantly to big current demands, for example to help with sudden acceleration.

When the Type-D is stationary, the petrol engine does not run. The air-conditioning can still operate if needed, though, thanks to that 48-volt electrical system. To move off, you press the clutch pedal down, select a gear, press the accelerator and the engine fires up as you engage the clutch and move away. There's none of the usual chatter and jerk of a conventional starter, because the electric motor performs the job of starting the engine.

Three modes alter how the electric motor is used. Sport mode uses all available motor assistance, but will use up the battery power so it cannot be engaged all the time. Normal mode adds battery charging on deceleration (regenerative braking) and rations the motor assistance. Economy mode maximises the deceleration charge. Pressing the sport button also opens valves in the intake and exhaust systems for a sportier sound – 'like a Formula One car at half speed,' says Tim Bishop.

Heated catalysts

One problem with turning an engine on and off is that the catalytic converters cool down, making for excess emissions when restarting. To overcome this, the Type-D has heated catalysts powered by the 48-volt electrical system that also handles the hybrid drive. They need an excess of air just after start-up to make them 'light off' again. This is neatly achieved by cutting the fuel supply to two cylinders for a few revolutions, so they act as an air pump.

Thus equipped, the Connaught Type-D should meet Euro 4 emissions, could qualify as an ultra-low emissions vehicle in the US were it to be sold there (for which there are no current plans), and should have average CO2 emissions of 150g/km.

British-built gearbox

The five-speed gearbox, made by Mitchell Cotts which also supplies gearboxes to Caterham Cars, uses proprietary internals in a specially designed casing. A six-speed sequential transmission is a possible future option.

Structure and suspension

A target weight of just 750kg without fluids (for the base model) doesn't have to mean carbonfibre panels or exotic, hard-to-repair, bonded aluminium chassis sections. The Type-D's chassis is built up mainly from laser-cut, flat steel and tubular sections, many of them with numerous large holes to save weight. It's designed to collapse progressively on impact, to be repaired easily and cheaply afterwards and to last well thanks to hot-dip galvanising.

Extensive computer simulation points to a five-star EuroNCAP crash test result, and Connaught plans to put the Type-D through the real test once it's in production.

The completed structure, with its Twintex inner tub and aluminium superstructure, has a torsional stiffness of around 7400lb ft/degree (10,000NM/degree). Its bonded-on Twintex polypropylene/glassfibre tub contributes to this figure, and the material has other advantages: recyclable, no resin smell, and good sound absorption. The aluminium body panels will be hand-formed at first, then pressed on soft tooling as production builds up.

Wishbones all round

Tim Bishop wanted the Connaught Type-D to have ride and handling much like that of the original Lotus Elan. Light weight, relatively soft springing and tight damping control are the keys here, and the Type-D has some intriguing componentry.

All the wishbones are aluminium castings, but while the upper ones are conventional the lower ones – all four of which are machined from identical castings – are anything but. They are large, wide and hinge on an axis at right-angles to the car's centre line. So the front ones are leading links, the rear ones trailing links. This reduces dive under braking and squat under acceleration, reduces geometry change as the wheels move in their generous suspension travel, and enables loads to be fed into the strongest part of the structure. The wide-based pivots allow the use of soft suspension bushes, too, which gives a smoother, quieter ride.

One effect of the geometry is that the roll centre rises as the car leans, so the inner rear wheel can still handle lots of drive torque. This means the Connaught doesn't need a limited-slip differential, although it will be an option along with traction control and an electronic stability system. There are no anti-roll bars, and the Connaught's light weight should render power steering unnecessary despite optional wide 35-profile tyres.

The spare wheel lies horizontally between the front wishbones, and forms an integral part of the crash structure.