Wednesday, November 23, 2016

Rolling Art: Jaguar XKSS "Continuation" Video (Jay Leno)

Above: Ecurie Ecosse Jaguar D-Type Short Nose; Below: Jaguar D-Type chassis (model)

Jaguar D-Type central (aluminum) monocoque and front (tubular steel) subframe.

Here's a link to the Jay Leno video on the new "continuation" Jaguar XKSS:

Return with me, now, to those thrilling days of yesteryear...

For much of its history, LeMans was a unique race.  The rules were written by the Automobile Club de l'Ouest (and still are).  Sometimes they accommodated cars built for the FIA's sports car championship, sometimes not.  After World War Two, the LeMans circuit was a special case too: smooth and flat with long straights and (mostly) tight corners.  Jaguar's solid rear axle worked perfectly fine there.  At longer, bumpier, circuits,  Jags were less competitive.

Doubtless because of Bentley's success at LeMans in the years around 1930, British sports car manufacturers were always more interested in LeMans than the FIA championship.  Before racing sports cars had bullet-proof reliability, the drama of a "last man standing" win in a 24-hour race gave British sports car manufacturers something to crow about when they (often) lacked the outright pace of continental race cars.

One reason I love postwar racing sports cars is that they were "freestyle," and so different from each other.  Ferrari (and Maserati) attacked LeMans with powah: 4 to 5 liter engines.  The Mercedes 300 SLR attacked it with technical sophistication and reliability.  Jaguar (and Aston Martin) attacked it with what they had in the parts bins for their road-going sports cars.

When the LeMans-winning C-Type became long in the tooth, Jaguar decided to put its proven (but underpowered) 6-cylinder engine into a radical new car: the D-Type.  The car's advantage would be light weight, a low-drag body, and improved disc brakes.  Malcolm Sayer, the designer, had a background in aircraft.

Sayer insisted on minimal frontal area and used an aircraft-style aluminum monocoque body/chassis center "tub"--an automotive first.  Tubular steel subframes hung from its front and rear to support the engine and suspension.  While this was no more rigid than the 300 SLR's fully-triangulated tubular space frame, it produced a lighter car.  The D-Type was both lighter and more rigid than Ferrari's twin-tube ladder frame.  Working with Jaguar, Dunlop developed a new (improved) brake/hub/wheel package that eliminated the brake fade of Mercedes and Ferrari drums while saving weight compared to the wire wheels customarily used.

The D-Type won LeMans in '55, '56, and '57.  Boom!  In fairness, it must be said that Mercedes probably would have won in '55 had it not withdrawn its team after the terrible accident: the 300 SLR swept the board except for LeMans.  When Jaguar decided to withdraw factory-entered cars from competition at the end of 1956, it had surplus chassis lying about.  What to do?  The XKSS.