Rotary Racer - Car Performance

National Final Goodwood 2011-10-16

Results

What a race and what a year. 3rd in the CC and first at every F24 race this year including the Final. The number "1" did not get us! The weather was brilliant, sunny and warm with just a slight wind (10 km/h ?). The car was RR8h. This was the same car as used at Castle Combe after the checkover and with the tail piece added behind the rear brake light.

The drivers choose to use the minimum of 5 drivers this race to give us the maximum chance of winning. They did choose to use the older, heavier drivers (Dan, Gareth and Ben) though as it was their last F24 race but have the longer 80 minute stint done by a ligher newer member (Dawn). The driver order was done in height order so that pitstops would be easier as the harness just needed to be shortened every time.

Car Computer Log

This shows the main items measured by the Rotary Racers car computer. They are:

Item	Description
Throttle	The position of the twist grip throttle from 0 to 100%
MotorCtl	The motor power output setting. The Car computer sets the motor power based on the drivers throttle position, the speed of the car and the current being used. There is a software algorithm to implement this "drive by wire" system. The Car computer drives the PWM (Pulse Width Modulation) Motor Speed controller with a duty cycle proportional to this value. 0 - 100%
Speed	The speed of the car in Km/H calculated from the magnetic read switch pulse generator by the Car Computer.
Voltage	The batteries voltage under load.
Current	The current being taken from the batteries.
Charge0	The charge left in the battery pack 0. This is calculated by the car computer using an algorithm that has been honed to match the battery discharge curves for the Yuasa batteries. It currently bases its results on the current being used from the battery.
Charge1	The charge left in the battery pack 1. This is calculated by the car computer using an algorithm that has been honed to match the battery discharge curves for the Yuasa batteries. It currently bases its results on the current being used from the battery.
Charge2	The charge left in the battery pack 2. This is calculated by the car computer using an algorithm that has been honed to match the battery discharge curves for the Yuasa batteries. It currently bases its results on the current being used from the battery.
BatPack	The battery pack in use (0, 1 or 2), the turbo button (4) and the Pitstop warning (8) . We generally change the battery pack with each driver change.
Temp	The Temperature of the motors casing in degrees C.
GPS	GPS position, speed and time together with lap position information
Misc	Other items describing the operation of the control system

The graphs show the overall data, the actual ASCII data log files are also available, from the links below, for detailed analysis.

Car Data Log

Car Data File

Practice Laps Data

Car Data

Car Data File

Notes

The Car was RR8h. This was the cars sixteenth race.
We used a 18:49 gear ratio as per Castle Coombe.
The Goodwood circuit is 3.862Km long and is fairly flat with sweeping corners. There was a light wind on the day (10Km/H ?).
The software was car27. The Car electronics worked perfectly. No changes for this race. Was the same as Castle Coombe: Changed GpsCurrent average to be taked an GPS position 1. This allowed us to obtain the average current for the last lap just as the car comes into sight/range leaving more time for the operator to decide and change the power levels. Added battery number switch to car.
The battery charge calculations worked well and the Voltage based charge measurement was about spot on.
The Car Computers "Average Current" setting was 16.00 Amps, the Control Speed was about 46 Km/Hour, this was tweaked during the race based on actual average lap current keeping it to around 17.5Amps. Dan was again in charge of car power management and again did a fine job as he has throughout the season, keeping a good amount of power left in reserve, just in case, followed by Dan's hallmark "FULL POWER" setting near the end :)
The only issue on the day was the Laptop's disk drive failing about two thirds into the race. This left Dan without info/control for a bit, but, we did have a spare laptop roughly setup to use and this went in relatively easily.
Drivers were: Dan Dando, Gareth Barnaby, Ben Millar, Tom Allington and Dawn Barnaby. The drivers drove excellently, went fast and kept out of trouble and keeping well clear of other cars by going around the outside (as far as we could see).
Pitstops were excellent, the practice paid off. One of the pitstops with battery change was down to 47 seconds and this was with the more detailed marshal checking of the harnesses etc.
The motors temperature kept below 37 degrees, 8 degrees lower than the hot Castle Coombe race. It was a cooler day.
The battery packs were kept in warmed battery boxes at the camping site the night before. They were fine although we did take the second battery pack (1 RR3,RR4) a bit too low and the voltage levels went a bit low. This was during the laptop failure and changover. The other battery packs were not used so heavily. We had about 7% left in the first set (after being used for 89 minutes) and probably around 23% left in the last set at the end of the race. We could have gone faster/further, but we were playing it safe, just in case of problems.
An excellent race an a superb 1st place result with an amazing 120miles. This is the same milleage we did at our Final win in 2009 but with 34% less energy. This is probably down to: The longer aerodynamic tail, the superb conditions on the day, the excellent driving and pit stops and the lack of a chicane.
An excellent, almost faultless race and superb year. It's goodbye to some of our staultwalt team members: Dan Dando, Gareth Barnaby, Ben Millar who have been with the team since 2006 and have helped design, build and race three cars and hello to Jacob, Micheal and Joe.