This was the 2010 National final and a great 3rd place result. The car was RR8f with the post roll modifications, smaller wheels and lower to the ground. We had also improved the behind the head fairing and had a new CNC produced roll-bar aerofoil. We did not have high expectations as we had not been able to race the car at speed after its major mods and re-tune it. Also our batteries, although good, were not the best (one pack 2 years old and the other a year old with about 4 races under there belt plus testing). The Greenpower new battery change and our new wheel costs precluded us from buying a new set of two for this final as we would have normally done.
During practice we tested with a 22:49 and a 19:49 ratio gearing. The results were not encouraging on the cars performance, but we gambled with the 22:49 to allow us to at least use every last once of energy from the batteries (especially if a cell failed as had happened in the previous two races with very old batteries). In actual fact during the race the cars performance was better than expected and we managed to be able to hold the race speed limit in the early stages. With heating we expected our batteries to be able to just about put out 26Amps on average for the race. We were using a touch over that and so had to power back a touch early on.
All was going very well and we were well up into second place with one last driver change to go when the throttle system failed. The Curse of having the "1" ! (Actually bad maintenance ...). Luckely this happened on the chicane and Ben managed to coast the car to a stop close to the track exit point saving the use of a recovery wagon (thanks to the marshal for pushing us in). The two cable holding bolts had come loose and the cable had pulled through (a bit of a maintainance failure and one more for the check list !). Unfortunately we could not get the cable back in due to the frayed end (should have soldered it ...). We had a spare button on the joystick intended to operate a solenoid in case of total electronics failure, so we connected this in place of the throttle potentiometer. Alas the switch didn't work (contacts dirty ??). Gareth had the idea to use the secondary car horn switch and so this was wired in instead (losing the lads designed, built and programmed "tunefull" car horn). We were off again, 19 or so minutes later, but had moved down to 4th place, behind SC07. James drove excelently using his left hand's thumb on the car horns button. With energy now in reserve, we took the car right up to the speed limit and managed to reclaim 3rd place (sorry SC07/Brian).
Suberb weather and a great fun race for us, although the throttle cable problem was disapointing, the podiums 3rd place snatched back after our problems was a great end to the day and season. It will be good to have the new style batteries after the issues with the old ones this year.
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. |
| BatPack | The battery pack in use (0 or 1), the turbo button (2) and the Pitstop warning (4) . 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 itmes 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.
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