R/C Tech Forums

Go Back   R/C Tech Forums > General Forums > Electric On-Road

Like Tree12Likes
Reply
 
Thread Tools Search this Thread
Old 05-10-2017, 01:20 AM   #16
Tech Master
 
gigaplex's Avatar
 
Join Date: Dec 2015
Location: Melbourne, VIC
Posts: 1,295
Trader Rating: 2 (100%+)
Default

Quote:
Originally Posted by DamianW View Post
Too much variation between the timing of one motor to the next. Typical variation was 5 degs with some up to 10 deg out when comparing motors of the same brand and batch.

Racers were buying multiple motors to find the ones with the highest timing.
How are the Muchmore GT motors with respect to this variability?
gigaplex is offline   Reply With Quote
Old 05-10-2017, 01:47 AM   #17
Tech Elite
 
Join Date: Jul 2010
Posts: 2,226
Trader Rating: 9 (100%+)
Default

Quote:
Originally Posted by gigaplex View Post
How are the Muchmore GT motors with respect to this variability?
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"
cplus is offline   Reply With Quote
Old 05-10-2017, 02:10 AM   #18
Tech Master
 
gigaplex's Avatar
 
Join Date: Dec 2015
Location: Melbourne, VIC
Posts: 1,295
Trader Rating: 2 (100%+)
Default

Quote:
Originally Posted by cplus View Post
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"
Thanks, they did look pretty even from a spectators point of view.
gigaplex is offline   Reply With Quote
Old 05-10-2017, 02:54 AM   #19
Tech Elite
 
Skiddins's Avatar
 
Join Date: Feb 2006
Location: Windsor, UK
Posts: 4,667
Default

Quote:
Originally Posted by xevias View Post
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.
ETS had fixed ESC's, handout motors and limited gearing for everyone (13.5 blinky class only), but there were still discrepancies in motors etc.
__________________
Xray T4'17, T4'14 (Wet Car)
Xray X12 2017
Xray X1'16
wlrc.co.uk (West London Racing Centre)
RCDisco.co.uk
Skiddins is offline   Reply With Quote
Old 05-10-2017, 05:39 AM   #20
Tech Regular
 
xevias's Avatar
 
Join Date: Feb 2006
Location: Shanghai, PRC
Posts: 341
Trader Rating: 1 (100%+)
Default

.

Last edited by xevias; 05-10-2017 at 06:56 PM.
xevias is offline   Reply With Quote
Old 05-10-2017, 06:21 AM   #21
Tech Elite
 
Join Date: Dec 2011
Location: Raleigh, North Carolina
Posts: 2,109
Trader Rating: 42 (100%+)
Default

This is a thread about fdr vs motor timing right?
ASM, mikeygar, Buckland and 3 others like this.
__________________
Aaron Moore

Serpent America/Desoto Racing, McFactory Motorsports, Team Trinity, Pro-Line/Protoform, Hobbywing North America/FalconSEKIDO, HRP Distributing, PTRC Racing, Ho B Max
Antimullet is online now   Reply With Quote
Old 05-10-2017, 09:51 AM   #22
Tech Master
 
IndyRC_Racer's Avatar
 
Join Date: Jul 2006
Location: Indianapolis
Posts: 1,814
Trader Rating: 9 (100%+)
Default

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.
RONAMYTH likes this.
__________________
I'm currently racing VTA. Check here for rules/info: http://www.usvintagetransam.com/
IndyRC_Racer is offline   Reply With Quote
Old 05-11-2017, 03:32 PM   #23
Tech Apprentice
 
Join Date: Aug 2010
Location: NJ
Posts: 99
Default

Quote:
Originally Posted by phatboislim View Post
get the motor tuned for the application and gear it to the track. way much simpler.

a team scream motor i had in my 12th i had tuned and geared it to the track, way easier. you dont have to worry about timing anymore. gear it to how it feels on the track and temp
What do you mean by get the motor tuned? I am new to brushless motors so not sure what you mean. Thanks again
RONAMYTH is offline   Reply With Quote
Old 05-11-2017, 04:53 PM   #24
Super Moderator
 
Marcos.J's Avatar
R/C Tech Elite Subscriber
 
Join Date: Sep 2003
Location: Semper Fi
Posts: 26,774
Trader Rating: 180 (100%+)
Default

Quote:
Originally Posted by RONAMYTH View Post
What do you mean by get the motor tuned? I am new to brushless motors so not sure what you mean. Thanks again
you can tune it by reshimming the rotor, polishing the rotor shaft, installing ceramic bearings, cleaning out the bearings and adding thinner oil, removing the metal or brass shims replacing them with plastics, changing the motor screws to aluminum screws. if the sensors are way off A B C , if you are patient and have a small tip solder you can actually try moving the sensors to get them closer together in degrees.

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 )
Marcos.J is offline   Reply With Quote
Old 05-11-2017, 06:17 PM   #25
Tech Addict
 
Join Date: Jan 2008
Location: Miami Beach
Posts: 741
Trader Rating: 6 (100%+)
Default

Marcos,

Where do you get the plastic spacers and or shims?

Last edited by Marcos.J; 05-11-2017 at 06:38 PM.
SouthFloridaApp is offline   Reply With Quote
Old 05-11-2017, 06:37 PM   #26
Super Moderator
 
Marcos.J's Avatar
R/C Tech Elite Subscriber
 
Join Date: Sep 2003
Location: Semper Fi
Posts: 26,774
Trader Rating: 180 (100%+)
Default

Quote:
Originally Posted by SouthFloridaApp View Post
Marcos,

Where do you get the plastic spacers and or shims?
pm sent
Marcos.J is offline   Reply With Quote
Old 05-12-2017, 07:47 AM   #27
Tech Apprentice
 
Join Date: Aug 2010
Location: NJ
Posts: 99
Default

Quote:
Originally Posted by Marcos.J View Post
pm sent
I would also like to know where you get motor tuning parts? Thx
RONAMYTH is offline   Reply With Quote
Reply

Similar Threads
Thread Thread Starter Forum Replies Last Post
Viper RC - mini-dub Radio and Electronics 12065 06-28-2017 04:51 AM
KARZ Calgary xrayroooahhhh Canadian R/C Scene 19109 05-12-2017 07:51 AM
Sean's RC articles. wingracer Rookie Zone 15 08-22-2013 02:47 AM
U.S. Vintage Trans-Am Racing squarehead Electric On-Road 14187 03-21-2012 01:43 PM
motor torque vs. hp question boosted 17.5 vs 10.5 TT_Vert Electric Off-Road 17 01-27-2012 06:56 PM



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off



All times are GMT -7. It is currently 09:00 AM.


Powered By: vBulletin v3.9.2.1
Privacy Policy | Terms of Use | Advertise Content © 2001-2011 RCTech.net