Carroll Smith felt strongly that every apprentice, every mechanic and every engineer that worked on a race car should have attended a driving school prior to doing so. The reason he thought this was a good idea (and even included in his own apprenticeship programs) is it is the best way to gain an understanding of how a car behaves. Learning about understeer or oversteer or balance or aero effects from a text book doesn't mean you know what understeer, oversteer, balance or aero effects actually are. You cannot have a kinaesthetic feeling for what they actually do to a car.
Gaining experience in how a car behaves will set an engineer apart, especially early in his or her career. Drivers, for all the skills, are not necessarily engineers. I have worked with numerous drivers over the years and there are some who strive to have a thorough understanding of the car and the laws of physics, and then there are those who drive on feel and can struggle to communicate what the car is doing, or even what they want it to be doing. If you, as their engineer, can decipher what it is that they want and need from the car, then you are going to earn your pay at the track. If you can understand elaborate hand motions and wishy-washy language from a driver who is not an engineer, you are doing very well.
Understanding how a car really behaves, in the real-world, transient conditions found on a race track does not come from university lectures, college classes or 2 inch thick text books. It comes from experience. It comes from taking the time to throw yourself in to the experience of racing. In all likelihood, no one will pay for you to learn to drive fast. You'll have to fund it yourself. Although as your experience and network grows, you're more likely to find someone who can help you make it happen a little cheaper. If you get the chance to start translating what a driver is telling you in to a real world take it. It will be incredibly valuable to you as an engineer, and it will probably be a lot of fun…
Everything on a racing car affects something else. Nothing works in isolation, and understanding the complex systems and links between the systems is crucial to engineering a winning car.
I've discussed before how compromise is needed to win races. That having an optimal overall system is more important and optimising each system on its own. But within those systems, you have often unseen and not so obvious links that can have a detrimental effect on the overall package.
I'll use a few examples to show you what I mean:
Most modern racing cars will have the ability to alter the engine map depending on driver preference and prevailing track conditions. This usually involves altering ever so slightly how power is delivered, however some championships may allow for more than this. There are situations where more aggressive, higher power engine maps are used during qualifying for example. These maps put a huge strain on the engine, but are only used for a relatively short period of time.
What is often overlooked is how these engine changes will affect the traction. A driver may complain that they cannot use the power when they want to out of corner, and so a less aggressive map will be used. However this will reduce the slip ratio for the driven axle, potentially inducing understeer.
Worse than this, your chassis engineer may decide that the issue of corner exit traction can be rectified through kinematic and geometry changes. If both chassis and engine changes are made, you can easily end up going too far and ruining the overall balance or making the car sluggish.
Changing ride heights is one of the fundamentals of setting up a race car. It will have a direct effect on the roll center of the car, and as such a dramatic effect on the handling. It is something that is usually something that can be changed quickly, and often by only a few millimeters (See Small Changes).
However the ride height does not act in isolation.
Changing ride heights will have an effect on the suspension kinematics; the way the wheel is controlled and moves under bounce and rebound. If this is not taken in to consideration when the ride height change is made, the results can be unexpected. Now most race cars will have adjustable everything on each wheel - camber, caster, toe, K, etc. - but if they are not changed in a systematic and controlled way, you can spoil the balance and handling of your car.
Another often overlooked effect of ride height changes is the affect it can have on the aerodynamics of the car. A car running a little too high or a little too low can be comes unstable and even dangerous. Adjustable splitters, diffusers and wings are there to accommodate changes where necessary but there is often a limit to what can be done.
Tyre Pressure Changes
Yes, even the simplest of changes to make can have knock on effects to other areas of the car. The tyres can be thought of as a spring, and they do play a crucial role in the spring rate of a wheel system as a whole. The entire system (from contact patch to chassis mount) has a spring rate that is known as the "Wheel Rate". Changing the tyre pressure will change this value.
To a degree, tyre pressure changes can be tolerated by the suspension system. Plus or minus a few tenths of a bar won't have dire consequences. But if you start playing around with larger pressure changes, you will fall in to a trap of chasing ghost springs in your system.
I have also seen cases where tyres were calibrated using nitrogen, but run using compressed air. The difference in Gas Constant meant the tyres were completely out of kilter with where they were expected to be. They came back from a run massively overheated and over inflated.
Before committing to a change on a car, think carefully about where the change will have an effect. What other systems might be altered by your change? How can the changes be negated or accommodated?
Compromise wins races. But knowledge definitely helps.
As a boy scout, I was taught to always be prepared. To expect the unexpected and to accommodate the unforeseen in any plan. Always bring backup matches camping. And complement that with a flint and steel. Water may be heavy, but bring a little more than you think you need. It will come in handy if you need to wash a wound or help a fellow scout out.
When approaching motorsport, the success stories use an identical mindset. They work off the principle that preparing in advance for all eventualities will give them an advantage over any and every team which don’t. Successful motorsport teams, and the successful motorsport engineers within them apply two golden rules to just about everything. Firstly:
Fail to prepare? Prepare to fail.
This statement is applicable to many areas of life, be it studies (revising for exams), business (hedging investments) or relationships (buy those flowers ahead of time!). In motorsport, failing to prepare removes any aspect of whether luck is on your side or not. Whilst “luck” is never a race winning strategy, after a short time on the front line of racing you will experience the affect that lady luck plays on the outcome of races. Punctures happen. Weather changes. Cars crash. However, if you have done the work beforehand and prepared for these outcomes, they don’t necessarily mean that all is lost.
A properly trained pitcrew can change all four tyres on a Formula One car in under four seconds (the current record is 1.92 seconds – well done to the Williams crew!). This is only achievable with practice. These guys in the pitlane don’t turn up on race day having never met or held a nut gun before. They practice for hours and days during the off-season time, and as often as possible during race season too. This practice, this preparation is what allows them to achieve the 3 second tyre change times. And this means that should their driver pick up a puncture, the damage is limited to seconds not minutes. The deficit is recoverable.
The second mantra by which the motorsport industry lives by is:
Two is one and one is none.
A little bit of a strange saying at first glance, but on inspection one that has true application in the motorsport industry. This motto refers to carrying spare parts to a race. Even for the most affluent race teams, logistics mean that part supply is finite. You can only bring what you can carry. The crux of this statement is that having only a single spare of any critical part on the car is tantamount to having no spares of that part. If the part fails and you replace it, you then have zero. The part could fail during free practice. It could even fail during engine warm-up. And then you are in a position that a single failure will stop the car from running.
Carrying a second spare alleviates this issue. A failure does not leave you reliant on lady luck. A failure just means you need to order another one after the race is finished. You are not racing on knife edge.
Being ready to deal with the unforeseen is a skill in and of itself. Planning for the worst is a key competency in every successful race team, and every successful motorsport engineer. By never leaving things to chance, mitigating the risk of failure and assessing worst case scenarios, you can make sure that luck remains on your side on race day.
Tom is an engineer working his way through the motorsport industry, sharing stories, anecdotes and lessons to help new engineers coming through the ranks.