Editorial

First of all a firm reminder that during wet conditions DO NOT PARK ON THE GRASS. Keep car parking to the surfaced areas around the track, and also please exercise great care driving in and out of the access road. Remember, if there are any more problems like the ones experienced last winter, there is still a possibility that we could lose access to the track site. Secondly, since space may be limited, please park as close together as possible around the track.

We have also had complaints recently regarding noise outside the entry gate early in the morning. If you arrive before the gate has been unlocked, please wait quietly in the side road. Remember this is a residential area and respect other peoples privacy.

So are they toys?

The final programme may have only lasted 3 1/2 minutes, but the day of filming at WLRC by BBC "Top Gear" produced a very positive image of model car racing. Some well produced action footage, intercut with intelligent dialogue and interviews with David Spashett, Chris Grainger, Neil Mead, Schumacher representative Dave Foster and club driver Derek Smith portrayed a sensible but fun approach to our hobby. Although Chris Grainger and David Spashett disagreed as to whether we were playing with toys, Neil Mead summed it up by saying even the full sized ones were really big toys, but we had just as much enjoyment playing with ours. Thanks to everyone who contributed to the programme, even if your bit didn't get used, and apologies to everyone else for any disruption caused by the filming. We are sure everyone will agree the results were worth it.

The BBC production team were very pleased with the help they received during filming and were impressed with how friendly everyone was.

There will probably be a follow-up article in an upcoming edition of Top Gear magazine.

Incidentally, when asked how Top Gear found out about WLRC, the answer was "through the internet."

Other Series

               The BRCA have decided that this years Winter Series shall be held indoors (perhaps that should be WIMPter Series). Not only that, but most of the rounds are about as far away from London as it's possible to get. We have entry forms at race control for those that wish to race. Most of the BRCA dates clash with our own Winter series, despite our dates having been set over a year ago.

As an alternative to the BRCA races, we are promoting the West London Winter outdoor series as a championship for "Real Racers." If you intend to race the WLRC Winter Series please fill in an entry form (available at race control), since we will need to enter all your information on the Race Control Computer (we use a different program for the winter championship).

Apparently people do race at tracks other than West London. We have received details of a series of evening meetings at the new Buckmore Park track, near Chatham, Kent. These are outdoors, under floodlights (should be interesting) with 3 rounds plus finals. Unfortunately the start time is 6pm so it could be difficult for anyone west of London to get there on time.

We have also received a note from the Racal-Decca club, reminding people that in all classes they race stock motors only. Please note to avoid the possibility of a wasted journey. Further details and entry forms are available from race control.

Rain stopped play

Despite the vagaries of British weather we do not have to cancel many race meetings. Unfortunately the final round of the summer series on Oct 24th was one of those days. Since it had been persisting down most of the night and with no prospect of improving, it was reluctantly decided to cancel the meeting.

Our apologies to all to those of you that turned up, sorry for the wasted journey.

Rather than re-schedule another meeting, we have decided that the points for the final round of the summer series will be extracted from WLRC members scores for the first round of the winter series.

This will not be too difficult to do, so the final positions for the summer championship will be published after the first round of the winter series.

Battery developments

Most people will be aware that there is a new breed of battery becoming available, the so-called "3000" cell by Panasonic.

These are of different construction to the cells which we at present use for model car applications, being of Nickel-Metal-Hydride (NiMH) construction, as opposed to the Nickel-Cadmium (NiCad) types which are common at present.

These new cells are not yet approved by the BRCA for competition use. One of the motives for changing to a different type of cell construction is an environmental one. The metal Cadmium, used in NiCads, is an extremely toxic material, and poses many problems over its disposal.

By changing to an alternative technology, it is hoped that pollution problems will be reduced.

NiMH cells were developed for use in items such as lap-top computers and mobile telephones. In applications like these they are subject to a fairly constant, moderate discharge current.

In a model car application the demands on cells are extreme, varying from a few milliamps at rest, to peaks of 50 or 60 amps or more when the car is accelerating hard.

One of the drawbacks to NiMH cells (and most other alternative types) is that they have a higher "internal resistance" than NiCads.

What's this internal resistance thing then?

A perfect battery will deliver the same terminal voltage, regardless of the load placed upon it. In practice there is no such thing as perfection and every battery possesses an "internal resistance."

This internal resistance has the effect of reducing the battery voltage when current is drawn from it.

 The drawing shows the circuit of a battery with its internal resistance represented by the resistor R.

If no current is flowing the terminal voltage is V1

When a current I is drawn from the battery, a voltage drop will occur across the resistor R. It is easy to calculate the value of the resistor using Ohms Law.

Ohms Law states that:

Resistance = Voltage/Current (R = V/I)

In this case the Voltage V is the difference between the off load Voltage (V1) and the on load Voltage (V2) Suppose the off-load voltage is 7.2Volts (the nominal voltage of a NiCad racing pack)

Suppose we connect a load which results in a current draw of 10 Amps and the voltage falls to say 7 Volts, then the internal resistance can be calculated as:

(7.2-7.0)/10 which is 0.2/10 which equals 0.02 Ohms.

This is quite small, but suppose the current is increased to 20 amps.

Since the internal resistance is known, we can calculate the terminal voltage for any current, again using Ohms law. This time the formula is:

V = I x R (Where V is the Voltage Drop)

So V = 20 x 0.02, which is 0.4 volts, ie a terminal voltage of 7.2 - 0.4 = 6.8 volts

So the effect of internal resistance is to cause the voltage to fall in direct proportion to the current drawn. This is what is referred to when people say cells have good "punch" - they have a low internal

resistance. If the cells are losing their "punch" the internal resistance is higher and the voltage falls more as the current demand is increased, therefore the car doesn't accelerate as quickly as it did when the cells were new. As cells age, their internal resistance increases due to impurities in their construction and chemical changes in the electrolyte.

NiMH cells have an inherently higher internal resistance due to the materials used in their construction, and therefore will appear to have less punch than NiCads. Whether production techniques will improve

the performance of NiMH cells remains to be seen, but in the mean time NiCads remain the best performing source of power for R/C cars.

NiMH cells need much more care when charging and storing. Normal NiCad chargers can be used, but it is vital not to overcharge them, since any heating during the charge process spells death. For this reason the peak detect circuits in many chargers may not be adequate, since they allow a degree of "overcharge" before shutting off. This is probably where stories of exploding cells originate, if people are charging them like NiCads. For optimum results a special charger will probably be required, so this will mean even more expense.

NiMH cells do not have the so-called "memory" effect of NiCads, so they may be stored either charged or discharged, but not shorted or with a load connected. In fact it is emphasised that storing them

shorted will destroy them.

Despite rumours to the contrary, NiCad cells have not been banned in the USA, and Sanyo/Trinity have just announced the availability of 2400 mAh NiCads, alongside the new NiMH 3000 cells.

It may be that in the longer term, environmental considerations could lead to the banning of NiCads. If that should happen we shall just have to accept the differing characteristics of the alternative types.

BRCA Results

The highly competitive BRCA summer touring car series has ended and the results reveal mixed fortunes for West London drivers. Whilst the overall champion in the super touring class was (unsurprisingly) David Spashett, WLRC regular Glen Doman was 5th, whilst Adam Rogers

achieved 9th position and was also the 2nd highest junior. Top WLRC driver Westley Payne finished in 22nd spot, with Jason Butterfield 31st and Chris Kerswell 33rd.

The GT/open class was a different story however. The series was dominated this year by "Mad Mike" Haswell, with a perfect score of FTD + A final win in each round (804 points). An excellent 2nd with 791 points was Stuart Cann, with Dean Gibson 6th, whilst a creditable 7th place and the highest placed "rugrat" went to Paul Castle. Other WLRC drivers included Nick Holloway in 11th and James and Paul Pedrick in 13^th and 15th places (all juniors).

Well done everyone and keep it up for next year

Beat 'em up time (again)

A team including West London driver Guy Pickett has been accepted to take part in this years series of the BBC programme "Robot Wars." Recording takes place late October so keep a look out for broadcast dates. Good luck to Guy and his team.