4 replies to this topic

[Garsted]

I have read in several places that Malcolm Sayer designed the Jaguar C & D-type bodies using very mathematical principles learnt presumably during his time at the Bristol Aeroplane Company.

At the risk of getting an answer I can't understand, does anybody know how he did it?

 

thanks, Steve

[JtP2]

Slide rule? Seriously, Frank Costin was reckoned to have designed the Vanwall body by mathematical formulas on wall paper spread on the dining room floor.

[Allan Lupton]

"Mathematical principles" probably refers to the Navier-Stokes equations which describe the motion of viscous fluid substance - and air is one such substance!

Serious use of those equations in aeronautics had to wait for the development of the so-called "super computers" but simplified use must date from around the period we are discussing.

[AAGR]

Whatever Malcolm Sayer did, his reputation was significantly over-hyped, both then and in later years.

 

Independent wind tunnel tests (taken at MIRA, for instance) later showed that the D-Type drag coefficient was poor. Later, similar tests showed that the XJS road car (yes, that is not a mis-print) had a superior drag coefficient ....

 

The fact is that according to those tests, and others produced in later years, the D-Type's top speed seems to be as much due to its small frontal area as to its shape.

[Allan Lupton]

Yes in automotive work the drag coefficient is referred to the frontal area and the actual drag results from the product of the two.

In the past we had advertisements boasting how low the drag coefficient of some car was and we aeronautical folk noticed that one manufacturer had modified a car so that it had perhaps 10% more frontal area with no change in drag - which of course gave a 10% reduction in drag coefficient!

Can't recall which car it was, but Lotus Elan and Elan+2 might give those results.