Car and Driver Calibration for Rookies
So, you’ve decided to participate in a Great Race or VCRA time-speed-distance (regularity) rally. The Event Schedule may indicate that a rally school is available to help you learn everything you need know about how to rally . . . True! Will you be ready to rally on the first day? Probably not!
You may learn a little bit about rallying, but you won’t have time to “calibrate” the car and driver. To be competitive in your first rally, you need to learn the basics of rallying and that includes calibrating your car and driver and preparing a Performance Chart. Remember, you only get to be a rookie only once.
The Concept:
A time-speed-distance rally makes one basic assumption that creates the challenge; that a car can stop and start instantaneously. Not event the fastest, most exotic cars in the world can do this. If your car could, and if you did every maneuver exactly correct, you might be on time. Remember, you loose time on every maneuver, both starting and stopping and turning. To perform well, you need to understand how you can get your car and driver to out perform even the most exotic car in the world. And it can be done!
Creating a Performance Chart:
What follows is an explanation on how to build a Performance Chart that you can use to make adjust for “lost” time doing the various maneuvers needed to compete in a rally.
First, you need to find a secluded road that has minimal traffic where you can create a course and drive through it multiple times. My partner and I usually go out into the countryside or in a subdivision that is not fully developed. I suggest that you set up two courses. One should be about a mile long and the second should be about a half of a mile in length. (The exact distance in NOT important. You will be looking for differences in time.) We mark the start and end of the courses with a stick with a flag attached. You could create a Performance Chart with a one-mile long course but it will take a lot longer when you do the slower speed runs.
First, time yourself as you run the courses at speeds of 10, 15, 20, 25, 30, 35, 40, 45 and 50 MPH. Do it 4 times at each speed. We usually run it in both directions to save time. The reason for course 4 runs is to get a good average. Remember to be consistent in holding the speed on each run. If you get a lot of variation, do more runs.
Your numbers will look something like this. They will not be exactly these numbers because the length of your coarse will be different.
Measuring time lost in Braking and Acceleration:
Now we have a basis for measuring the time lost in braking and acceleration. First, lets measure the time lost in acceleration. To do this, drive to the starting flag. The navigator should give a start count; 3, 2, 1, go! If the driver jumps the count, wack him or her and do it again. It’s important that the start is done with consistency. Start the stopwatch when you say, “go” and stop it when you cross the end flag. You will get numbers that look like this.
Using the averages we can determine the lost time on acceleration. Take the difference between the average run time (time to run the course without start/stop) and the time taken when starting from a stop. This is the loss on acceleration.
Now we have to determine the loss on braking. This is done by entering the coarse at the designated speed. Start the stopwatch when you pass the entry flag. Tell the driver to stop and the end flag. Stop the stopwatch when the car rocks back after the stop. Your numbers may look something like this.
Using the averages we can determine the lost time on braking. Take the difference between the average run time (time to run the course without start/stop) and the time taken when stopping on the end flag.
Creating the Performance Chart:
These are the basis for any numbers you might need to run the rally. I like to organize them in a fashion that I can read them quickly. I use a chart format. Put your numbers in a chart similar to the one below.
Now you can use simple math to fill in the blanks. For instance, if the loss on acceleration from 0-30 is 2.4 seconds and the loss from 0-50 is 5.2 seconds, the loss from 30 to 50 would be the difference or 2.8 seconds. Put 2.8 in the junction where 30 and 50 meet. For a chart like this to work, the driver must always accelerate and brake at the same pace. The navigator must always measure stops in the same manner (at rock back)
Now What?
Now that you have this chart that probably took most of a day to create, how would you use it?
A common instruction during the rally would be to have you stop at a stop sign. The Rally Master will usually allow 15 seconds at the stop. Again, they assume instantaneous stops and instantaneous starts. Lets say you were driving into the stop at 40 MPH and you were instructed to go 25 after the stop. Using the chart, the loss on stopping would be 3.7 seconds (the intersection between 0 and 40). The loss on acceleration is 2.0 seconds (the intersections between 0 and 25). The rally master gives you 15 seconds of which you have used 5.7 (3.7 plus 2.0) in stopping and starting. Therefore you stay at the stop sign for 9.3 seconds instead of 15.
Another type of instruction that this chart can be used for is turns. An instruction may call for you to make a turn to the right. Your entry speed may be 40 MPH and the speed at the completion of the turn is 25 MPH. The instructions assume instantaneous speed change at the apex of the turn. Assume that you will make the turn at 15 MPH. First the loss on braking is 2.0 seconds (intersection of 40 and 15). The loss on acceleration is 1.0 seconds (intersection of 15 and 25).
Staying on Course is key:
The hardest part of rallying is staying on course and time. This chart may help you stay time but not on course. If you miss a sign or a turn you may find yourself “Lost in the Bluebonnets” or “Abducted by Aliens”. This chart is meant to give you a guide of what time to stay at stop signs and how much time you loose on turns. For it to work well, the driver has to be very consistent.
Course instructions are given to you 20 minutes of your start time with the Great Race and 45 minutes ahead of time with the VCRA. Use the time before you leave to mark them with stop sign pauses and turn losses.
If you choose not to make one before the rally, you can make some guesses on stop signs. Using 8 –10 seconds hold time will keep you in the ballpark. Using 3 – 4 seconds on turns will do the same.
There are lots of ways to calculate the data on this chart. You will hear other methods and most of them work well.
If you have and questions on this, feel free to contact me at Loubiere06@verizon.net.
Bill Loubiere
Editor’s note: Bill Loubiere was introduced to the Great Race in 2001. He has participated in two cross-country Great Races, 13 regionals and one National VCRA Event. In 2007, Bill and his son, Dan began the year with a 3rd place finish in Great Race Texas, placed 1st in the VCRA National (Silver Division) and scored a 2nd overall; he also placed 2nd in the 2007 Coker Tire Challenge with Richard Fredette driving and finished 3rd in the VCRA All Stars for Autism.
