Another bucket list must read checked off...thanks Grand Prix Legends.
Finally after many years of dumb procrastination, forgetfulness, and occasional wishing about it, now have a re-print paperback copy of Denis Jenkinson's c1958
classic, The Racing Driver, The Theory and Practice of Fast Driving.
First time thru it is kind of a slow sloggy read with too long paragraphs of uncertain direction all bundled into a rambling jumble of way too much detail, side stories, and occassional apparent inabilities to stay on point or get to one.
Then later, maybe days later, something clicks and that chapter has to be read all over again, now that it is starting to make some sense why he went on so long about some peculiar aspect of sidecar riding that is of particular interest to the professional F1 driver.
Then on and on and on about slip angles after summing it all up with the simple declaration that science and engineering confirm the optimum slip angle for a racing car is designed to occur when 15deg of steering lock is applied.
Have to wonder if that's still the case.
(Thinking probably not).
There's a graph to prove less is not enough and more is too much. It was also noted, if the driver is not getting out there to 15degs of lock at the tire patch
that they are not going fast enough. Apparently the optimum speed is just past way too fast to get thru the turn otherwise. Better get it right.
Two things that are interesting in his analysis of a racing driver's skill, (entirely unlike mere mortals), is first, compelling a car at will to demonstrate an oversteer or understeer attitude regardless of its predisposed inclination, and unlike the rest of humanity, do it with incredibly focused nonchalance within a few fractions of a second at the precise micro-second the move must begin and end, and second, doing it at somewhere over 180mph where there is zero tolerance for error.
Also clearly no doubt in Jenkinson's view any use of steering input, even zero lock, can be "applying lock."
Paying attention to use of the term lock has narrowed the search for a reasonable practical definition to "the use of steering input to direct the car away from the line of minimal resistance," to a line of greater resistance and greater grip.
Note the line of minimal resistance is where the car would go if the driver released the steering wheel and let the car roll. It is the same as the line of least resistance, as others use the term, and the fastest way thru a turn if that line is available from entry thru exit. If not available at the speed that must be maintained, it is time to try a little lock.
"Lock" is a verb. It means "to hold in position." So where the steering wheel is relative to zero at 12 o'clock, or any number of degrees either way, is secondary to the art of applying lock to set the car on a certain line.
In the context of suspension dynamics, is it more appropriate to think of the steering wheel as a lever, that pivots off the rack, to keep the suspension steady out near the break-away limit of no more marginal returns?
How do we reverse engineer 15deg of tire patch lock into Grand Prix Legends setups?
BTW, Denis rode professionally on winning sidecars and rode with Stirling Moss to win Mille Miglia. Many of the side stories used as examples, (like a book within a book), are about his many years of very special direct experience with racing and race drivers.
Then it finally hit, on a sidecar the rider is the active suspension.
On the Mille Miglia, the rider is as much a part of the car as its driver.
Stirling could not have made a better choice, and together they proved it.
This post could have been much longer if all the scope of this book had been covered.
Forgot to note the two turns DJ mentions as being especially suited to serious applications of lock are Abbey and Woodcote, (nice they are on the same circuit), and also the last turn before the front straight at Rouen.
Read this book, then read it again and again and again...
Maybe it won't help you be faster.
It will help you become a better driver and better understand firsthand what it was all about back then.
Edited by John Woods, Jul 12 2018 - 09:13 AM.