William C. Mitchell aka Racing by the Numbers
January 18, 2014
On January 17, 2014, William C. Mitchell passed away suddenly at his home in Mooresville, NC. He was known to his friends as Bill. He graduated from CalTech in 1967 with a degree in Mathematics specializing in numerical analysis, or how to perform difficult calculations. This was followed with a Masters from Stanford University in 1969.
His interest in auto racing began while watching a Can-Am race in Edmonton, Alberta in 1969. In 1972 he began serving as a SCCA flagman in the San Francisco region. He was soon working at 20 - 30 races a year up and down the west coast as well as the SCCA Runoffs at Road Atlanta. In the 80’s, he began covering races for the San Francisco Region publication, “The Wheel”. The race reporting soon expanded to the magazines, “Autoweek” and “Formula”. He began following the Trans-Am series when Ford returned to professional motorsports in the mid-80’s where he met the engineers and team managers. Tom Gloy was driving Mustangs, Jack Roush was running a Mercury Capri for Greg Pickett, John Dick was leading the DeAtley Motorsports team of Chevrolet Camaros driven by David Hobbs and Willy T. Ribbs with Dennis Fischer building the motors.
When IBM released a personal computer, complete with 5.25” floppy disks holding 360kb of data, he needed a project where he could learn to program on the new computers. He had heard of “camber curves” so decided to write a program about suspension. With the advent of affordable and portable computers, data acquisition began to be used by the motorsports industry. It was at this time that Bill began working on the Debrief series of data acquisition analysis programs. Bill is generally considered to be the first programmer to begin the development of serious data acquisition software designed specifically for the motorsports industry. In fact, many of the screen graphics and methods of analyzing data originally developed by Bill are still being used by virtually all of the current data acquisition software developers. This includes the basic algorithms used to construct an accurate track map. This led to spending the 1991 and 1992 seasons with Chip Ganassi’s CART team. The drivers were Eddie Cheever and Arie Luyendyk. The 1993 season was spent with the Roush Racing GTS effort where Tom Kendall returned to racing and won the Driver’s championship. In 1994 Roush and Kendall switched to the Trans-Am series and won three driver’s championships and several manufacturer titles from 1994 to 1997. In 1997 the Roush team won eleven consecutive Trans-Am races, marking the end of factory involvement.
1998 was spent with Huffaker Engineering in the Trans-Am. Bruce Qvale competed for Rookie-of-the-Year. In 1999 Bill worked with Bruce Barkelew’s RaceWerx team where Brian Simo finished second in the Driver’s Championship and GJ Mennen was second in Rookie-of-the-Year points. In 2000 he worked with Ruhlman Motorsports in the Trans-Am and DSTP in the Formula Atlantic series. The DSTP effort was limited to testing, but Buddy Rice won the Driver’s Championship with five wins in twelve races.
Bill presented SAE papers at the Motorsports Engineering Conferences in 1998 and 2000. The 1998 papers were “Asymmetric Roll Centers” and “A Method for Data Alignment”. The 2000 paper is “Training Test Drivers with Data Acquisition”. This describes a training project with the Transportation Research Center in Ohio. He was still writing technical articles for Racer Magazine in their Tech Trek series. For over a decade, he was also a sponsor and judge for the Formula SAE competition.
Bill's greatest contribution to the motorsports and automotive industry was the development of his kinematics (geometry analysis) software packages known as WinGeo3. Bill pioneered this type of software which allowed the user to study how a suspension system would move under dynamic conditions. Bill's Premier/Data WinGeo3 version allows the race engineer to download track data directly into the program, allowing the engineer to look at step-by-step suspension motion throughout each portion of the track. Bill was a visionary in that the development of this type of software was years ahead of any other kinematics software system. Aside from giving the race engineer intimate knowledge of how the suspension was moving, (camber, castor, bump steer, scrub, changes, etc.), it also allows the engineer to view and record side and rear view instant center motions, which, in turn, can be used to determine the proportion of forces moving through the suspension components versus the springy bits.
Bill's software and his personal genius were never fully recognized because Bill was primarily interested in one thing -- the mathematics of motion. As the eccentric that he was, he had little time for promoting himself or his software; however, those designers who took the time to learn and use his software were rewarded with a one-of-a kind program that still outperforms all other kinematics software today. Many companies tried to copy Bill's software but none, to date, have come close to duplicating what his WinGeo3 programs can do.
Once a user showed that they had put the time in to learn and use his software, Bill was always happy to tailor new software to their particular suspension system needs. As an example, a UK based race team running several BMW M3 touring cars wanted to analyze that car’s suspension kinematics but the factory race team indicated there wasn't any software that could do that type of analysis. Within a week, Bill had provided the team with a M3 WinGeo3 model.
Bill never stopped working at improving WinGeo3 and had just recently developed a series of equations that would automatically change the length of the upper control arm so that the suspension system would maintain a constant moment arm length underneath the center of gravity throughout any realistic combination of ride and roll. This, in turn, produced very stable camber, caster, scrub motion, etc. throughout the suspension’s operational range.
Bill was a mathematical genius who was able to retain very complex and lengthy algorithms in his head. He once rattled off 47 pages of hand-written vehicle dynamics algorithms completely from memory that he and two other people had developed over a series of weeks.
Sadly, at the time of his death, Bill no longer had any living relatives. However, through the years, he built his own close-knit family of friends. He was dearly thought of and will be greatly missed by all who knew him. He will be remembered for his brilliance, gentleness and generosity.
