Brushless Slot cars

Brushless motors could go the same way as other changes in motor technology have got into slot cars past.
At first the standard new technology from some other application is applied to slot cars.
That doesn't provide much, if any advantage.
Then guys who understand what makes slot cars work start developing motors specially for slot racing using the new technology.
Extra power isn't necessarily the best way of using new technology - as with previous changes in motor technology slot cars often gained more from lighter, smaller, lower c of g motors than they did from extra power.
Of course just plonking a different sort of motor in an existing chassis isn't usually the best way to get the benefit of the new motor, chassis need to be developed to make full use of the new motors.
Then motor and chassis developments feed on one another to produce a better car.

A gain in efficiency is a huge advantage in planes or cars that have to carry their batteries around with them. In slot cars efficiency is much less significant as long as motor cooling is adequate.
Commutator and brush wear are an issue with brush motors (particularly the quick ones) so brushless would have an advantage there.
Bearing wear would be just as much of an issue with or without brushes.

Will brush less take over in slot cars?
With home set cars, every penny that can be cut from the production cost matters, so the very low production cost of basic brush motors is a big advantage.
With faster cars the customer is prepared to pay more for better performance. Is it worth investing in the development of brushless slot car motors for these? That's a decision for the guys who can afford to make the investment.

Dr_C said:

What about more cars per amp and smaller voltage drops along the track (I.e. more cars and more consistent power)?

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Agreed increased efficiency gives you that.

However, is the fluctuation of track voltage a problem in digital racing? Many digital experts seem to be of the opinion that IF the track wiring, connectivity between sections and power supply are up to the job , fluctuation of track voltage aren't big enough to be a problem. For sure there are many posts on how to get good enough track wiring, connectivity between sections and power supplies.

How much of an advantage is less amps for the same power (aka increased efficiency) in digital slot racing? The current needed for a couple of dozen digital cars with brushed motors can be supplied by readily available power supplies, indeed substantially higher current power supplies are in use on some non-digital slot car tracks.

Just supposing fluctuating motor power is the real concern, is there another way of solving it?
While the lower current of brushless motors would somewhat reduce the fluctuations in track voltage, it cannot eliminate it. Some electronics in the car could deliver pretty consistent motor power even though the track voltage was fluctuating. So although we are still stuck with a fluctuating track voltage that doesn't necessarily mean we are stuck with fluctuating motor power. The simplistic approach would be to put an off the shelf linear voltage regulator in the car, but that would add mass and produce heating in the car. Redesigning the control chip to adjust the PWM so the motor delivered consistent power should add very little mass or heat in the car.

Dr_C said:

On the subject of very fast slot cars...

When will be the next attempt at a slot-car land speed record...? any photos of the current record holder... was it brushless? what was the max speed achieved (actual and scale)? And over what distance?

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When? If and when somebody builds a suitable straight line track. A few attempts to do that apparently haven't got beyond the planning stage, the use of a long enough building and the cost of building a track long enough track seem to have been the main reasons they didn't get any further.

The fastest slot dragsters reach about 130-140mph for a very brief period.

Apparently the closed circuit record is 139.784 km / hr = 86.858 mph. This used a track with two 12 meter straights, one upside down (!), with 180 degree loops joining them.

The world record for a "King Track" is 1.286 seconds for the standard 155ft lap - that works out at just over 82mph average. In recent years the King Track record has been broken several times, most recently in early 2018. Obviously the maximum speed will be higher than the average, but there doesn't seem to be any reliable measurements of how much faster. Here's a video of the record lap
They all use brushed motors and are 1/24. They are all actual speeds.

There are some speeds recorded on long straight "line land speed record" type tracks, these are very much slower than the average speeds round circuits. Some of these times were set with severe restrictions on the type of car. They are records within those rules.

They all use brushed motors

Scale speed is something of a can of worms - it often sparks off a discussion about which of the different ways of calculating scale speed is correct, a discussion which rapidly ascends way of the heads of most contributors. Unless anybody really really wants to rerun that sort of discussion, I reckon sticking to actual speeds is good as it is both easy for everybody to understand and unambiguous.

Dr_C said:

1/ How much faster than a superfast brushed slotcar motor is a similar sized brushless motor... lets have some speed trap strobe photos please... the benchmark should be a NSR King46 motor... right?

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Comparisons between brushless motors with an NSR King46 motor would be interesting, I look forward to seeing the results. So would comparisons with superfast brushed slotcar motor

A King is an example of a "long can" (Mabuchi FK-180 size) motor, These are the largest and heaviest motors commonly used in slot cars these days. Superfast brushed slotcar motors are considerably smaller, around half the weight and rev to several times the speed.
Some while ago the average revs of a superfast brushed slotcar motor in the fastest sort of slot car ( a "wing car") were calculated from the lap time, gear ratio and tyre diameter, the result was.110k rpm. This was only average rpm for a lap, the maximum speed must surely have been higher.

The suppliers of high reving brushed motors warn against free running them at anywhere near full voltage. The problem is they will fail due to excessive revs. apparently the commutator is what usually goes first, figures in excess of 200k rpm are often quoted. Of course the revs in a car don't reach that so comm failures are rare.