Account
Pictures
More cogs
Rotary Racer - Car Performance
Rockingham 2015-10-11
Results
Excellent weather with about 25km/H wind but cool.
A superb set of races. 1st in F24-1, 8th in F42-plus and 1st in F24-2.
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 |
F24+
F24 Race 1
F24 Race 2
Practice Laps Data
Setup
| F24 Race1 gears | 17:48 |
| F24 Race1 batteries | RR13,RR14 (ok) |
| F24+ Race gears | 19:48 |
| F24+ Race batteries | RR15,RR18 (not so good) |
| F24 Race2 gears | 17:48 |
| F24 Race2 batteries | RR19,RR20 (good) |
After race the batteries had the following voltages at home.
| RR13 | 11.81 |
| RR14 | 11.84 |
| RR15 | 11.80 |
| RR18 | 11.85 |
| RR19 | 11.83 |
| RR20 | 11.95 |
Writeup
Work on RR9 this year has been mainly to cope with rule changes and to provide added driver protection. Along with that we had quite a few new team members to bring up to speed (pun intended!). However some enhancements to the aerodynamics (with a new windshield and bonnet arrangement, new mirrors and improvements to running gear) have been recently made.
This year there was a huge field of excellent teams from across the country competing. At the sharp end there were at least 6 different teams who could take the podium positions so it would be a tough race for all. There had been plenty of pit stop practices at CCS as we knew the race would likely be tight. The batteries were selected, charged, warmed and we were ready to go. The practice lap times for all cars are available on the web for all to see and we could see our competition was going very well indeed. All the team were up for the challenge.
The pit garages were lively with all of the teams working on getting their cars ready for the race. There was an excellent excited buzz all around. The new Terazord car from Bristol Grammar School was next to us looking superb. We will see a lot more from that one ...
The first race started with an unusual rolling lap start, which we hadn't done before, so it was all a bit new. Tristan started off fine though getting our race underway. Unfortunately the Purple Predator, one of our main challengers for the title had an issue that their power was still off. Luckily they got going fairly quickly. Another of the fastest competitors, the Black Bullet suffered a blown fuse which cost them precious minutes to fix which was a shame. Once the race had got going though, all was not well with RR. Our battery charge indicator displayed on the pit side laptop via the telemetry was showing the batteries were no where near as good as they should have been and current usage was higher than expected (or hoped for !). So the pupil laptop engineer told the driver to shut down the power by lowering the "warp" factor. As the race progressed we had to shut down the power even more and were going backwards with respect to the teams at the front. Kevan was noticing the lap times increase. "Oh well" we thought, "that has blown it, we chose the wrong battery set." However, we carried on with some fine driving by Tristan and later Tom with some good pit stops. Joe was the last and lightest driver. By then, although we were lower down the field of cars, the batteries weren't looking so bad, our reduction in power had given us a bit more energy to play with, and with the lighter driver the "warp" was turned up a bit more. Amazingly enough, we started to creep back up the field and in the last few laps the lead cars started to slow as their batteries waned. We managed to pass both the Purple Predator and RLR2, which was going superbly, in the last few laps and managed a first place position. The whole team was ecstatic, we hadn't expected that.
The car was brought back to the pits as fast as possible so that we could change the motor's gear for a larger one for the F24+ race. With the poorer batteries in the F24 first race, the F24+ team, Tom and Dawn decided to gear slightly slower than they had planned to make sure of the batteries lasting and some better efficiency from the motor. The whole team had screwdrivers and Allen keys turning to get the gear changed and the car ready for the F24+ race. The F24+ race went well for us, but we didn't have the battery energy we expected and so the gearing choice was right for the day.
There was plenty of inter-team fun ("banter" going on, the Weald team, Red Flame team and RR's team were trading mis-information about their teams gearing choices for the next race and selfie photos were going on, including one taken by a member of the Weald team with RR's team "sabotaging" one of the Wealds cars! Also various videos were being shot for a later pupil produced short video on the event. (A link to this can be found on the home page of this website.)
We managed an 8th place in a very competitive F24+ race. Matt with Reprobation managed to take the win over Dave with Jet, just. Those two have been battling each other all year and have raised the performance of their cars to new highs in the process!
Again RR was brought back for another quick gear, battery and driver change with all of the younger team members working, with some adult helpers to do the initial Allen key loosening and final Allen key tightening. RR was ready and sent out to challenge for the second F24 race. Unfortunately we were placed at the back of the grid for some reason, together with RLR2, possibly because we were a bit late queuing for a grid walk that was taking place. We thought that this had blown our chances as this placing could easily lose us 3 minutes on most of the front runners and probably the championship with the new rolling start scheme. But nothing could be done about it, so we kept our hopes high and rose to the challenge. Thankfully GP told the drivers that they could pass cars going much slower and so our loss in time was reduced to a minute and a half in the end. Thomas followed RLR2, carefully passed some of the cars, but we were well down the field with a lot of work to do. Luckily this battery set, which we thought was our best, was actually our best and looked good from the telemetry read outs. So the pupil laptop engineer told the driver to keep the warp power levels high and we burnt those amps moving up through the large number of cars. RR had made our way up to about 9th, when Louise our last driver was quickly put in in one of our teams quickest pit stops ever. Louise carried on the trend, and with her fast, smooth driving we continued to climb up the field with various "encouragement" over the walkie talkies. The team tried to compete with team Hummingbird's cheering (we lost !). Again we managed to pass the Purple Predator in the closing stages, but Dylan, the new car from CAUC was finding its feet (tightening the brush cap did help!) and the CAUC girls were flying. Did we have enough energy? The batteries looked good, so the power was raised again and we decided to risk it. RR just managed to pass CAUC in the closing laps and our battery gauge reached 0% just on the finishing line in first place !
The team were ecstatic, and the celebrations started, an excellent end to our Greenpower year. Now to the winter, with two new team members, to where Greenpower really happens: to the research, idea generation and design work for RR10 ...
Notes
- These races "featured" a rolling start, hence the low throttles in the first lap.
- We had to do a time penaltyin F24-2, there was a slow lap that accounted for this.