Going Brushless: Report from 1/12th Scale 2006 Euros
During the 2006 European 1/12th Scale Championships in Gran Caneria, I had the chance to test out the new LRP Sphere Competition Brushless ESC in combination with the LRP 4 Star Vector Brushless Motor.
For more information on the 2006 1/12th Euros see http://www.ec2006.org/
For background spec and technical info on the LRP Sphere/Vector Brushless system see http://www.lrp-electronic.de
Currently in the UK 2005/2006 season, BRCA sanctioned events for 1/12th scale do not allow the use of Brushless systems. As a result of this not many UK 1/12th racers have gained any significant brushless experience so the Euros were going to be a watershed.
The Base Modified setup
I arrived for the Friday practice sessions with my standard setup for modified loaded into the car. I use a KO VFS Competition ESC with various motor options. My most used motor has to be the Corally Black Series 10*2. This motor seems to have the best run time for me when timed around 11 degrees and pulling 40mm/rev.
As you can see, the brusless setup is 28 grams heavier than my modified brushed setup.
Drive Smooth
By nature I am a smooth driver. I tend to not throttle jam and being a bit of an “old man” I like to allow the car to roll around for the first 2 mins at least. I will use the sweeper at the end of the straight to save energy and try not to feel the end of the sick too much until the last 4 mins.
End of Season Cells
We all know that cells loose capacity as they age with charge/discharge cycles. I must admit that I aimed to compete with “end of season” GP3700 cells. These cells have lasted me the whole UK BRCA national series running both 19T and modified events.
I do keep an eye on things and I know that from testing all my packs prior to the event , they charge to around 4200 mAh (4.5A charge 0.04 pack delta on a ProTrak charger). Discharge capacity for the 20A cycle on the Protrack is in the order of 3600 mAh (0.9V per cell cutoff). Hence these cells are not the best but they are not garbage either.
Run Time Issues
As the grip came up during Friday practice and by the 4th round with my brushed setup I started to dump! It became obvious to me that run time was going to become a major stress for me.
After the first grading round I was 21st overall (this was not going to last! I am one of those drivers cursed with the ability to drive a new track reasonably quickly but then not improve!)
The Euros track was as large as we see on the UK scene with the top pace being around 37 laps.
I realised that my duration situation was just going to get worse…….
LRP to the Rescue!
I had already arranged the possibility of testing the LRP Sphere/Vector system in association with Helgar Racing (the UK distributor of LRP) and LRP. The LRP Company had Reto Konig (R&D Manager at LRP) in attendance giving technical support to drivers at the meeting.Reto hooked me up with the Sphere Competition ESC and the 4 Star version of the Vector brushless motor. I only had the time between adjacent timed practice rounds to fit the combo to my CRC Carpet Knife!
Fitting the System
Reto had already fitted a thinner 16 AWG wire loom more suited to 4 cell 1/12th scale cars. None of us would want to run the 13 AWG wire that the system is supplied with (suitable for TC racing), there would be too many tweak issues to the Motor pod on a 1/12th scale car.
The ESC also had a small 470uF 16V power capacitor pre fitted to small power wires coming from the side of the unit.
My first fitting attempt was a failure (!) mainly down to me rushing to get the car turned around for the next qualifying session. Less haste and more speed was required.In the end I settled for the layout you see in the pictures with the sense wire running under the tweak brace and the three motor power cables following the centre line of the car.
LRP make the sense wire in two lengths (Part no 81920 is 100mm and 81910 is 200mm). I had the shorter 100mm harness which is just right but only just long enough, you have to fit the ESC as I have shown or the short sense wire will not reach.
I made sure the motor wires did not obstruct the damper tubes, restrict rear pod movement or catch on the underside of the body in any way.
The LRP Sphere Competition controller is the lowest profile brushless unit available and does not need a fan or heatsink for 4 cell 1/12th cars. This is good news as it just fits under the Parma Zytek shell that I tend to use. This shell is one of the lowest shells at the sides so if this works for me it will work for any body I think.I just managed to turn the electrics refit around in time. The rest of my tyre and car prep was a bit of a disaster due to time pressure but I managed to do it all in the one hour available. To be honest, people have said that fitting brushless to a 1/12h car is a stress, I did not find this to be true. Give me two hours not under meeting pressure and I would have a neat job done and time for a cup of tea and a sandwich.
The Basic Settings
The Sphere programming user interface is similar to the Quantum QC3 and Nosram clones so it was familiar to me even without the manual.
Reto had preconfigured the speedo with the following settings which I did not change.
Mode 1: Auto Cell System Setting 2 = NiMH 4-7 Cell racing mode
Mode 2: ADPC Power Profile Setting 3 from 6 Levels increasing punch
Mode 3: Initial Brake Setting 2 from 6 Levels increasing initial brake
Mode 4: Automatic Break Setting 2 from 7 (0-6) Levels increasing drag break
I don’t use breaks in 1/12th scale so the Mode 3 setting was irrelevant to me. This is not true of the Mode 4 setting. Brushless motors do not magnetically “cog” so it is important to simulate the natural breaking of a modified motor to create the same weight transfer and slowing as you lift off the throttle. LRP (Reto) advised me that the Auto Brake setting of 2 would be like a “standard” modified motor so I went with that.
Gearing
I was advised to start at 30mm/rev (wow.. that’s low!) so I did exactly that. I had to buy a few new pinions and ended up on around 21/96 on 45mm dia tyres. Remember that this is the 4 Star motor here.
In Use
I took it easy for the first two laps…. Then started to push….. oh its fast! Feels like my 10*2 … more top end speed with a really smooth power delivery. The auto break felt no different to my brushed motor and I was straight onto my previous lap times.
So… after 4 laps I decided to “drive it like I stole it” just to see what would happen. I nailed the thing for the remaining 7 mins. It was not pretty and I am not proud of myself ;-) but I had a lot of fun.
The car just ran and ran to the end. I lifted it off the track and the motor was warm but not hot to touch. The post race discharge (now there is a novelty) showed me coming back with 300mAh left in the tank. Oh Joy.
Now…. through Saturday (qualifying) and Sunday (finals) I did not touch the motor or even think about it. I did not dump once and in fact, I won the first leg of my final (from 5th) in the last lap as the leader dumped in front of me ;-) I had legs to the end.
After 3 legs I was 3rd overall in the D final. Not bad seeing Marc Rheinard had come out to play with the CRC trinity and the 12 disciples thrown in for good measure.
In hindsight maybe increasing the Mode 2 power profile from 3 to 4 may have been interesting .. oh well, next time.
Conclusion
To my mind the LRP Sphere/Vector Brushless system is a total winner. I spent an enjoyable two days of competitive racing at the Euros without the anxiety of dumping and I did zero motor maintenance.
I was left in peace to think about racing lines, car setup and tyre choice.
It is true that the top three cars in the A final (Team CRC!) were running brushed motors and maybe it can be argued that with brand new top class cells and Oscar Jansen sat at your pit table brushed is very fast indeed. I am mature enough to realise that my failure to make B and A finals at this level has nothing to do with horsepower. I am simply not good enough, and this may never change. I just want to keep on learning and enjoying my racing. The Sphere/Vector combo just added to my enjoyment of the whole weekend.I really hope we pass Brushless for the 2006/2007 BRCA season. I know how I will be voting.
In preparation for the last UK modified national at Chesterfield I have taken the LRP system out again and it is sitting in front of me without a car. Oh well. Better charge the comm lathe pack again……
Many thanks and regards to
Helgar Racing http://www.helgerracing.com/
LRP Electronic http://www.lrp-electronic.de/
Reto Konig
David Splashett
