[Closed] Custom diecast of the day

Marvellous piece of work

Was the purpose of tonneau covers back in the day to aid streamlining or just to decrease...

... wind buffeting inside the cockpit?

Marty, i think a bit of both.

The tonneau partially enclosed the cockpit that would otherwise disturb airflow and create undue drag; as a result, tonneau equipped cars ultimately went faster.

It seems pretty clear that it was for aerodynamics......

as the cover doesn't look like much more than a glorified shower curtain and it was attached to the top of the windscreen rather than a covers normal attachment to the dashboard.

It would also fit with their reworking of the body work for both the front and rear fenders - including adding skirts on the back and redoing the exhaust system so it went out the back.

photo no longer available

photo no longer available

It seems that it was only for the Le Mans race that DBR1's were 'streamlined' to this extent - at least as far as the photos I was able to pull up on this car.

Thanks, Paul & Frank. Without access to windtunnels, I suppose striving aerodynamic efficiency...

... for race cars was all "seat of the pants" guess work. Quite a contrast from today.

Wind tunnels and aviation practices .......................................

"When the Jaguar D-Type appeared in May 1954 it was the most advanced car of its time and its construction owed much to the aircraft industry experience of Malcolm Sayer and his colleagues at Jaguar's Experimental Department. The D-Type pioneered a monocoque center section fabricated from aluminium alloy sheet with riveted fasteners, standard aircraft practices in the Fifties, but the first use of monocoque techniques for a competition race car. The so-called bag tank, a leak-proof rubber bladder fuel tank, was another aircraft industry innovation while the rear suspension was from the C-Type, with lateral torsion bar springing but now with parallel trailing arms. Mounted under the bonnet was the venerable XK unit in competition form fitted with dry sump lubrication that both improved reliability and reduced the engine's height. This allowed Sayer to further reduce the frontal area and smooth airflow across the body. The design was routinely tested in wind tunnels, reducing aerodynamic drag by 28-percent between the C- and D-Types and 20-percent between the ultimate 1953 C-Type and the long- nose D-Types of 1955."

http://cdn.shopify.com/s/files/1/0043/4522/files/Short-NoseD-TypeRecreation.pdf?101054

Chris

Part 2 ....................................

"By the early 1950s Lyons was investing heavily to achieve success in motor racing which he believed would increase Jaguar's appeal to ordinary motorists. He hired Malcolm Sayer, a gifted design engineer in aviation to develop a competition model or C-Type racing car. The mathematical principles and aerodynamic testing techniques, including wind tunnel and smoke tests, that Sayer brought to Jaguar have been attributed to the C-Type's wins at Le Mans in 1951 and 1953."

http://classiccars.about.com/od/classiccarsaz/a/HistoryofJaguar.htm

Chris

Chris, great stuff! Thanks for posting this info!

You are welcome Marlowe.