Infraction data log help

[sleekone]

increased motor timing to Highest (20) setting and made 3 passes today. didn't really see any gains...what do you guys think from the logs?

115mph

119mph

119mph

 

[The Donut Man]

I think to compare these, you would have to overlay a 20° timing graph onto a 0° timing graph to see any trends. I will say that your throttle pulls are a bit exponential; the faster you go, the quicker you pull the trigger. That'll make your voltage drop worse than it needs to be. This is what you want your Motor Power Output to be (see below). I'm on the opposite side of the spectrum; as you can see, I take a whopping 9 seconds to get to WOT and because of that, I get less time (3.5 seconds) before I have to get on the brakes.

Btw I'm really surprised at your motor temps with such high timing; what are the external can temperature readings for those runs?

 

[sleekone]

I think to compare these, you would have to overlay a 20° timing graph onto a 0° timing graph to see any trends. I will say that your throttle pulls are a bit exponential; the faster you go, the quicker you pull the trigger. That'll make your voltage drop worse than it needs to be. This is what you want your Motor Power Output to be (see below). I'm on the opposite side of the spectrum; as you can see, I take a whopping 9 seconds to get to WOT and because of that, I get less time (3.5 seconds) before I have to get on the brakes.

Btw I'm really surprised at your motor temps with such high timing; what are the external can temperature readings for those runs?

View attachment 103058

I agree on my throttle pulls, I have a habit of pulling more as I speed up. I’m working on trying to even it out more. I’m pretty sure I’m running out of transmitter range by the end of the run too- using a DX3 with Spektrum SR315 receiver currently so will be looking to upgrade that next I think.
external motor temps are super low, like mid to high 90°s but nothing over 100° usually even after 3 runs maybe 105° tops.
what I find interesting are the motor temp drops right at 100% power..any thoughts?
I’m running dual NTF fans off a 3s lipo.

 

[sleekone]

i inverted colors on a run with highest timing (20) @119mph and then overlayed a run with normal timing (10) @127mph
kinda hard to read but i see my currant peaks a lot quicker on the higher timing - not sure if that's just my heavy trigger finger?
any thoughts on the timing comparison? 3 runs significantly slower than normal timing makes me wonder - do i just need a longer run/softer touch getting to WOT?

 

[LibertyMKiii]

Looking back at some of your other logs the RPMs and MPH don't exactly align between the 127 and 130 mph runs. Have you been changing the pinion also?

I can clearly see that with higher timing it was drawing more amps, didn't reach the RPM as before, and overall lost power/speed:

127 MPH - 32.2k rpms and 342A
130 MPH - 31.7k rpms and 330A
119 MPH - 30.3k rpms and 370A (20 degrees timing)

 

[The Donut Man]

Not accounting pinion changes, it sounds like you just don't want any timing

 

[LibertyMKiii]

Not accounting pinion changes, it sounds like you just don't want any timing

Agreed, I would actually love to see whatever the setup was on the 130mph run and decrease the timing to 5 and then 0 degrees and see what the results are.

 

[sleekone]

Looking back at some of your other logs the RPMs and MPH don't exactly align between the 127 and 130 mph runs. Have you been changing the pinion also?

I can clearly see that with higher timing it was drawing more amps, didn't reach the RPM as before, and overall lost power/speed:

127 MPH - 32.2k rpms and 342A
130 MPH - 31.7k rpms and 330A
119 MPH - 30.3k rpms and 370A (20 degrees timing)

No change in pinion. Running 35/34 for both.

Agreed, I would actually love to see whatever the setup was on the 130mph run and decrease the timing to 5 and then 0 degrees and see what the results are.

I can totally do that, today I think! I’ll go down to 5 and run a few passes then 0 and run again and share the log graphs. ??

 

[LibertyMKiii]

No change in pinion. Running 35/34 for both.

I can totally do that, today I think! I’ll go down to 5 and run a few passes then 0 and run again and share the log graphs. ??

I think there are variations in the graph details. We know the new SkrRC GPS is crazy accurate...

Based on the RPMs and gearing being the same your 127mph run should have been faster
127 MPH - 32.2k rpms
130 MPH - 31.7k rpms

If I plug in your gearing into a calculator with around 32k rpms and your gearing, it says that you need 4.65" (118mm) tires to be going 127-130 mph. It bugs me when math does not add up like it should. I know the calculator is accurate, so my suspicion is the RPMs in the data logs are off.

Either way I am looking forward to your results trying lower timing.

 

[The Donut Man]

I think there are variations in the graph details. We know the new SkrRC GPS is crazy accurate...

Based on the RPMs and gearing being the same your 127mph run should have been faster
127 MPH - 32.2k rpms
130 MPH - 31.7k rpms

If I plug in your gearing into a calculator with around 32k rpms and your gearing, it says that you need 4.65" (118mm) tires to be going 127-130 mph. It bugs me when math does not add up like it should. I know the calculator is accurate, so my suspicion is the RPMs in the data logs are off.

Either way I am looking forward to your results trying lower timing.

Maybe the gearing ratio was put into the Castle software differently on each graph? That's always the first thing I check.

 

[LibertyMKiii]

Maybe the gearing ratio was put into the Castle software differently on each graph? That's always the first thing I check.

These are calculations I am doing outside of the castle software. I am only taking the RPM from the castle data logs and then plugging in the 35/34 gearing and the 3.3 differentials. Motor KV is a factor that is variable but since we have an exact RPM it does not matter. We are just looking at motor rpms and the pinion it is driving at those rpms.

I can plug in what appears to be an odd voltage value, but this is to get the 32k rpms and the MPH is much less. I had to increase the tires size to get the speed to match up...

 

[jkflow]

Which GPS are you using for these runs?
If it's the SkyRC 015 you can go into it's datalog and get accurate measurements. Not instant gratification in the field but helps you compare the runs.

 

[The Donut Man]

These are calculations I am doing outside of the castle software. I am only taking the RPM from the castle data logs and then plugging in the 35/34 gearing and the 3.3 differentials. Motor KV is a factor that is variable but since we have an exact RPM it does not matter. We are just looking at motor rpms and the pinion it is driving at those rpms.

I understand, but I'm suggesting that maybe the RPM from the data log is wrong because @sleekone put in different gear ratio than 35/34 for one of the logs.

 

[LibertyMKiii]

I understand, but I'm suggesting that maybe the RPM from the data log is wrong because @sleekone put in different gear ratio than 35/34 for one of the logs.

My understanding is that the motor RPM is only effected by the motor pole options? Maybe I'm wrong.

 

[Mr.Duke]

Set raw data without smoothing for an accurate rpm reading. Even “smoothing low” for the data plotting will throw it off.

 

[The Donut Man]

My understanding is that the motor RPM is only effected by the motor pole options? Maybe I'm wrong.

So I just tried it with one of my graphs: at 30/34 gearing (which is the actual gearing of the run), max RPM = 37,626. Changing the gearing ratio to 34/34 on the same graph, max RPM = 42,641. I guess it does all make a difference!

 

[LibertyMKiii]

So I just tried it with one of my graphs: at 30/34 gearing (which is the actual gearing of the run), max RPM = 37,626. Changing the gearing ratio to 34/34 on the same graph, max RPM = 42,641. I guess it does all make a difference!

Wow that is so weird to me.... I cannot imagine why castle would do that!?
@robert@castle what setting do we use in the logs to see the true RPMs?

 

[robert@castle]

Wow that is so weird to me.... I cannot imagine why castle would do that!?
@robert@castle what setting do we use in the logs to see the true RPMs?

Much of the datalog viewer is based on the air controllers that first had datalogging before we pushed the feature into the car software. There is an option for the gearing because helicopters don't care about motor RPM they care about drops in headspeed. If you set the gear ratio to be FDR and set the motor poles correctly it should tell you wheel RPM. For cars, most people will set it to 4 pole motor and set the gear ratio to 1:1 so they get the motor shaft RPM, That is a more useful metric to drivers. The RPM recorded by the ESC is electrical RPM because it doesn't know how many poles the motor has. To the ESC every motor looks like a 2 pole motor so if you have a 4 pole motor and have it set to 2 pole, it's going to show double the RPM.

if you are setting the pinon/spur gears into the gear ratio setting, it will tell you RPM of the center drive shafts which isn't a practically useful metric.
We also recommend not using smoothing because it can hide some spikes in data.

 

[LibertyMKiii]

Much of the datalog viewer is based on the air controllers that first had datalogging before we pushed the feature into the car software. There is an option for the gearing because helicopters don't care about motor RPM they care about drops in headspeed. If you set the gear ratio to be FDR and set the motor poles correctly it should tell you wheel RPM. For cars, most people will set it to 4 pole motor and set the gear ratio to 1:1 so they get the motor shaft RPM, That is a more useful metric to drivers. The RPM recorded by the ESC is electrical RPM because it doesn't know how many poles the motor has. To the ESC every motor looks like a 2 pole motor so if you have a 4 pole motor and have it set to 2 pole, it's going to show double the RPM.

if you are setting the pinon/spur gears into the gear ratio setting, it will tell you RPM of the center drive shafts which isn't a practically useful metric.
We also recommend not using smoothing because it can hide some spikes in data.

Thanks Robert that is very helpful, and I appreciate the background on why it is this way.

 

[sleekone]

Set raw data without smoothing for an accurate rpm reading. Even “smoothing low” for the data plotting will throw it off.

I’ve got it set at no smoothing. ?

I understand, but I'm suggesting that maybe the RPM from the data log is wrong because @sleekone put in different gear ratio than 35/34 for one of the logs.

Nope, I’ve got the gearing set the same for both runs at 35/34. But I’ll double check just to make sure!