14LikesTrying to understand FDR vs. Motor timing
05-10-2017, 01:47 AM
#17
They vary a little bit. But it's not massive. The speed on track has been shown to be very equal and that's what really matters. Not what figures they show on a zero load tester.
What you also need to understand also when people say something varies by 5,10,15 degrees or whatever it doesn't mean enough if you don't know the base.
The difference in kVA/rpm with motor A vs motor B at 20 vs 25 degrees is much, much less than the same pair of motors at 55 vs 60 degrees. Hell, you will find 20-30degree spread can be less than a 3degree spread at 60deg on many motors.
Accuracy of the poles is also a factor, a sensor showing, say 45-50-55, will perform way worse than one that has 49-50-51.
It's not quite exactly the case, but you tend to get the rpm performance of the lowest reading, but all the heat of the highest reading.
Yet both are set at "50"
What you also need to understand also when people say something varies by 5,10,15 degrees or whatever it doesn't mean enough if you don't know the base.
The difference in kVA/rpm with motor A vs motor B at 20 vs 25 degrees is much, much less than the same pair of motors at 55 vs 60 degrees. Hell, you will find 20-30degree spread can be less than a 3degree spread at 60deg on many motors.
Accuracy of the poles is also a factor, a sensor showing, say 45-50-55, will perform way worse than one that has 49-50-51.
It's not quite exactly the case, but you tend to get the rpm performance of the lowest reading, but all the heat of the highest reading.
Yet both are set at "50"
05-10-2017, 02:10 AM
#18
They vary a little bit. But it's not massive. The speed on track has been shown to be very equal and that's what really matters. Not what figures they show on a zero load tester.
What you also need to understand also when people say something varies by 5,10,15 degrees or whatever it doesn't mean enough if you don't know the base.
The difference in kVA/rpm with motor A vs motor B at 20 vs 25 degrees is much, much less than the same pair of motors at 55 vs 60 degrees. Hell, you will find 20-30degree spread can be less than a 3degree spread at 60deg on many motors.
Accuracy of the poles is also a factor, a sensor showing, say 45-50-55, will perform way worse than one that has 49-50-51.
It's not quite exactly the case, but you tend to get the rpm performance of the lowest reading, but all the heat of the highest reading.
Yet both are set at "50"
What you also need to understand also when people say something varies by 5,10,15 degrees or whatever it doesn't mean enough if you don't know the base.
The difference in kVA/rpm with motor A vs motor B at 20 vs 25 degrees is much, much less than the same pair of motors at 55 vs 60 degrees. Hell, you will find 20-30degree spread can be less than a 3degree spread at 60deg on many motors.
Accuracy of the poles is also a factor, a sensor showing, say 45-50-55, will perform way worse than one that has 49-50-51.
It's not quite exactly the case, but you tend to get the rpm performance of the lowest reading, but all the heat of the highest reading.
Yet both are set at "50"
05-10-2017, 02:54 AM
#19
There is another solution that is looking very good. I will probably implement it in my race series next year.
Scorpion has introduced a stock/spec ESC that has an RPM limiter built into the software. Scotty is currently using them in F1 for his ETS series with great success. When you load the software, you simply pick the max RPM like any other setting. It then blinks a specific color and pattern to confirm.
Using these will almost eliminate certified stock motors and complaints about inconsistent fixed timing handout motors.
I see these ESCs (whoever manufacturer) becoming the standard for VTA, USGT, F1, and 17.5 blinky in the near future.
Then you just gear for infield or race organizers set an FDR limit too.
Scorpion has introduced a stock/spec ESC that has an RPM limiter built into the software. Scotty is currently using them in F1 for his ETS series with great success. When you load the software, you simply pick the max RPM like any other setting. It then blinks a specific color and pattern to confirm.
Using these will almost eliminate certified stock motors and complaints about inconsistent fixed timing handout motors.
I see these ESCs (whoever manufacturer) becoming the standard for VTA, USGT, F1, and 17.5 blinky in the near future.
Then you just gear for infield or race organizers set an FDR limit too.
05-10-2017, 09:51 AM
#22
I look at the original question this way...
Timing allows me to adjust the motor so that it runs in a more efficient manner, depending on application. The same motor may need to be set differently when running in a 1/12 pan car vs. 1/10 4wd vs. off-road car. Also because of the manufacturing differences of motors, adjustable timing allows me to set the motor where I want for my application.
Most motor manufacturers set the timing from the factory at a safe point where it won't be damaged. The manufacturers may offer recommended settings based on application or class.
Racers will often used different devices to find exactly how many amps the motor is drawing (with or without a load) to find the point of diminishing return. That is to say as a motor has more timing it will draw more amps from the battery. At a certain point, the amp draw will actually hurt the performance of the car on track because a discharge voltage graph will look more like a steep curve than a flat or gradually sloping line. Also excessive timing might not be very efficient and cause the motor to heat up. Hot motor/magnets tend to work less efficiently, so while the motor may be faster in the beginning of a race it might actually be slower at the end.
FDR or gearing allows me to choose a gear ratio that works best at a particular track and/or layout. For example I may want to use a "slower" FDR on a small technical track because it should allow my car to accelerate to its potential maximum speed in a shorter amount of time. In other words, on a small track there is no need to gear a car to go 100mph when the car will never get over 20mph.
----------
Thankfully there are a lot of people out there who have done a lot of the work trying to figure out timing and FDR for specific tracks and/or classes. Most often they will gladly share that information. But it is best to consider any of that information to be a general starting point as there are many variables that affect how a car performs on the track. Be prepared to changes your settings and take notes to see what changes you make to your car improve your performance.
Timing allows me to adjust the motor so that it runs in a more efficient manner, depending on application. The same motor may need to be set differently when running in a 1/12 pan car vs. 1/10 4wd vs. off-road car. Also because of the manufacturing differences of motors, adjustable timing allows me to set the motor where I want for my application.
Most motor manufacturers set the timing from the factory at a safe point where it won't be damaged. The manufacturers may offer recommended settings based on application or class.
Racers will often used different devices to find exactly how many amps the motor is drawing (with or without a load) to find the point of diminishing return. That is to say as a motor has more timing it will draw more amps from the battery. At a certain point, the amp draw will actually hurt the performance of the car on track because a discharge voltage graph will look more like a steep curve than a flat or gradually sloping line. Also excessive timing might not be very efficient and cause the motor to heat up. Hot motor/magnets tend to work less efficiently, so while the motor may be faster in the beginning of a race it might actually be slower at the end.
FDR or gearing allows me to choose a gear ratio that works best at a particular track and/or layout. For example I may want to use a "slower" FDR on a small technical track because it should allow my car to accelerate to its potential maximum speed in a shorter amount of time. In other words, on a small track there is no need to gear a car to go 100mph when the car will never get over 20mph.
----------
Thankfully there are a lot of people out there who have done a lot of the work trying to figure out timing and FDR for specific tracks and/or classes. Most often they will gladly share that information. But it is best to consider any of that information to be a general starting point as there are many variables that affect how a car performs on the track. Be prepared to changes your settings and take notes to see what changes you make to your car improve your performance.
05-11-2017, 03:32 PM
#23
What do you mean by get the motor tuned? I am new to brushless motors so not sure what you mean. Thanks again
05-11-2017, 04:53 PM
#24
want to try to get the timing as close as possible if you get lucky you can get them perfect.
in theory the closer they are the more efficient the motor is.
then is the fine balance at the track trying to find the combination of timing and gearing. (if you have a chassis Dyno then you can get it almost spot on before hitting the track )
05-11-2017, 06:17 PM
#25
Marcos,
Where do you get the plastic spacers and or shims?
Where do you get the plastic spacers and or shims?
Last edited by Marcos.J; 05-11-2017 at 06:38 PM.
05-12-2017, 07:47 AM
#27
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
