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  Astra RNR2 Cosworth
 

Astra RNR2 Cosworth Astra RNR2 Cosworth Astra RNR2 Cosworth Astra RNR2 Cosworth Astra RNR2 Cosworth Astra RNR2 Cosworth
Click here to save all images    Image credits: Wouter Melissen 

Model history:
Click here to download printer friendly version In 1966 the talented British amateur racer Roger Nathan and leading aerodynamicist Frank Costin teamed up to created the Costin-Nathan racing car. Powered by a diminutive Hillman Imp engine, it combined Costin's slippery design with an unusual monocoque chassis constructed from plywood, much like Costin's earlier Marcos GTs. Despite the unconventional design, the car was remarkably successful both in the hands of Nathan himself and other customers.

By 1969 the writing was on the wall for closed cockpit sports racers with the lighter, open cars coming to the fore. Nathan recognised these developments early and started developing an open version of the existing design. His original partner, Frank Costin, had already left the company, so the Costin-Nathan name was dropped. Instead the new car was known as the Astra, inspired by the Royal Air Force motto 'Per Ardua ad Astra'. The first model was known as the RNR1; short for Roger Nathan Racing.

A development of the earlier designs, the RNR1 also featured the trademark plywood monocoque chassis. Its primary advantages were the relative light weight and high rigidity. Attached to both ends of the chassis were steel tubular subframes, onto which the suspension, engine and gearbox were bolted. At the front, the suspension consisted of double wishbones, while the rear-end featured reversed lower wishbones, top links and twin trailing arms. Girling disc brakes provided the stopping power.

While his previous cars used Imp and later BMW engines, Nathan opted to use a two-litre version of the venerably Coventry-Climax FPF engine for the Astra. Famously based on a fire-pump engine, the twin-cam 'four' produced around 180 bhp in this guise. This was mated to a Hewland FT 200 gearbox. The car was clothed in a fibreglass body that was built by Williams & Pritchard. They converted the existing design penned by Costin to a Spider. Despite the relatively heavy engine used, the completed car weighed less than 500 kg.

Nathan debuted the new Astra in March of 1969 at Mallory Park and immediately claimed the car's first victory. Another win followed a fortnight later but the glory was short-lived as the RNR1 was soon dwarfed by rivals using the much more powerful Cosworth FVA. Nathan quickly responded and readied an FVA equipped RNR1. This turned the small Astra's fortunes once more and Nathan continued to race successfully in national events. Several customers also showed an interest and it is believed 5 RNR1s were built.

Encouraged by the success of the Astra in its debut season, Nathan used the winter months to fine tune the design. Seeking to improve the handling, particularly under braking, the front suspension received the most attention with changes to the geometry and all-new, lighter uprights. Dubbed the RNR2, the modified car also received the latest Cosworth FVC engine. Displacing just under 1.8 litre, it was good for around 245 bhp. Two new Astras were built ahead of the 1970 season; one for Nathan himself and the other for Guy Edwards.

A clutch problem in practice delayed the RNR2's debut until the prestigious BOAC 1000 km at Brands Hatch. Partnering with Mike Beckwith, Nathan fought his way up the highly competitive field to finish 16th overall. In national events Nathan did manage to score a couple of wins but the latest Chevrons and Lolas were clearly quicker. Edwards also added a win to the tally of brightly liveried machine late in the season. For 1971, he switched to the latest Lola.

Nathan realised he had taken the development of the car as far as he could and retired his RNR2 after winning the Martini Trophy at Silverstone. He had hoped his performance as a driver would have attracted the interest of other teams but when no drives materialised, he left motor racing altogether. In the five seasons the Costin-Nathans and Astras were raced, the unconventional machines more than once managed to upset the established teams and manufacturers. This can be attributed to both Costin's original design and Nathan's skill behind the wheel.


Chassis: 38
Chassis 38 The first of two RNR2s built, this was the example raced in 1970 by Roger Nathan himself. He scored two victories before retiring the car in August of that year. It was subsequently sold to France where it was eventually acquired by restorer and historic racer Yvan Mahé. He worked his magic on the car and briefly campaigned it during the 1990s before he sold it on. The current owner bought the car in 2005 and had it repainted in Nathan's original livery.

Between 2005 and 2007, he campaigned the Astra in select CER (Classic Endurance Racing) events. Among them was the 2006 round at Donnington, where the car was reunited with Roger Nathan himself. On the occasion of the launch of his new autobiography, Nathan stepped back behind the wheel of a racing car for the first time in 36 years.

Recognising the (historic) value of the highly original Astra, the Swiss owner opted to retire the car from active service soon after. Focusing on racing his other cars in historic events, he has now decided to consign the car to the RM Auctions 2012 London sale on October 31st. The rare machine is offered without reserve at an estimate of GBP 70,000 - 90,000.

Article by Wouter Melissen, last updated on October 29, 2012

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General specifications
Country of origin Great Britain
Chassis number 38
Numbers built 2
Produced in 1970

Engine
Configuration Ford Cosworth FVC Straight 4
Location Mid, longitudinally mounted
Construction cast-iron block, aluminium head
Displacement 1.79 liter / 109.2 cu in
Bore / Stroke 85.7 mm (3.4 in) / 77.5 mm (3.1 in)
Valvetrain 4 valves / cylinder, DOHC
Fuel feed Fuel Injection
Aspiration Naturally Aspirated
Power 245 bhp / 183 KW @ 9000 rpm
BHP/Liter 137 bhp / liter

Drivetrain
Body fibreglass panels
Chassis box-section triplex monocoque with front and rear subframes
Front suspension double wishbones, coil springs over dampers, anti-roll bar
Rear suspension reversed lower wishbones, top links, twin trailing arms, anti-roll bar, coil springs over dampers
Steering rack-and-pinion
Brakes discs, all-round
Gearbox Hewland FT 200 5 speed Manual
Drive Rear wheel drive

Dimensions
Weight 550 kilo / 1212.5 lbs

Performance figures
Power to weight 0.45 bhp / kg

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