[Dr_C]

The RPM's reached will obviously depend on the length of the straight, you'd need a big track to get the max theoretical revs...or small diameter tyres.

Indeed, and a whole bunch of other traction related factors too.

And, just to add, this is not an attempt at any kind of speed record. I have two simple objectives here:

1/ to build test-cars which are capable of reliable 10m/s, 12.5m/s and (hopefully) 15m/s performance over a 5meter acceleration lane from a standing start, followed by controlled deceleration. This is for a new digital slot car system evaluation.

2/ to explore whether, with proper design of the performance envelope, that brushless motored slot cars can perform competitively with brushed motored slot cars across a wide range of slot track designs that are currently in use (i.e. home, local club, national and international).

Maybe 1 and 2 are mutually exclusive, let’s see.

c

[Kevan]

NSR are current ISRA world champions...using brushless motors a couple of months ago... first worlds for brushless.

[Kevan]

Here's a good graphic showing how well brushless motors fared internationally in 2024...
...it's safe to say that list will only get longer

   

[Dr_C]

The last two posts nicely capture progress of brushless motors across international competitions - which is great to see - thanks for these posts.

Unless I am mistaken all of these results are achieved in the analog racing domain using sensorless motors. Please correct me if I am wrong on these two points.

The focus of this threat is digital racing and the potential application of ‘sensored’ brushless motors.

As I say, the previous two posts are helpful reference points - so again thanks.

c

[Kevan]

Yes, analogue, non magnet, sensorless brushless outrunners.

RC cars used sensorless before sensored was available.  Sensorless were 'coggy' at low speed whilst sensored were smooth from a standstill.

[Dr_C]

Yes, my approach is aimed at:

digital, sensored, in-runners.

I wonder if the reduction of ‘cogginess’ will help in digital racing?

Perhaps…

• Better control in lining up on the starting grid?
  
• Better control on R1 curves?
  
• Better control when navigating pit lanes?
  
• Parade laps?
  
• Lane-changing?
  

It’s going to be interesting exploring this digital performance space. But that will require a sensored brushless digital decoder (stage 3 of the plan I outlined in the initial post on this thread)… so plenty to be getting on with in 2025!

c

[Dr_C]

The recent discussion on this thread has helped me to shape the details of my ‘so-called’ stage 1 experimentation. I now realise I should include some sensorless motors in the trials too. This should help to answer the questions I pose in my previous post relating to ‘cogginess’.

Recap: stage 1 uses commercially available in-runner brushless motors plus a commercial ESC (electronic speed controller). Wireless control is via a commercial Spektrum DSMR transmitter/receiver combination. Track power is either 7.5V DC or 12V DC with step-down to 7.5V via a commercial high efficiency buck converter. A smart LED as discussed elsewhere will provide stay-straight/lane-change commands to the in-track lane changer electronics.

My next post will show the hardware configuration for ‘stage 1’ plus, hopefully, some on-track results. This may take a few weeks!

Meanwhile, I'm happy for the debate to continue on this thread - that’s the way we all learn from each other :)

c

ps the unloaded max wheel RPM for the 5500KV sensored brushless motor running at 7.5V is 18,200 RPM as measured by tacho. Transmission ratio is 31:13.

[Dr_C]