R/C Tech Forums

Go Back   R/C Tech Forums > General Forums > Radio and Electronics

Reply
 
Thread Tools Search this Thread
Old 12-24-2014, 11:49 AM   #106
Tech Elite
 
Slapmaster6000's Avatar
 
Join Date: Sep 2004
Location: Edmonds, Wash.
Posts: 2,947
Trader Rating: 14 (100%+)
Default

Yep, yep. Dynos are probably only useful to the owner. To say I got this result with this set up is going to be challenging to duplicate on another piece of equipment.

I checked with Charlie at Novak, the Sentry data logger is no more. I would have to research other products for data logging. I haven't done that yet.

And I agree, being consistent with your test parameters is key. Voltage is a given!

I should get off the computer. I'm sure there is some wrapping I should be doing!

Happy holidays everyone.
__________________
Stay dialed my friends!
www.slapmastertools.com
Team Roche USA
Team Orca orcharc.com
Slapmaster6000 is offline   Reply With Quote
Old 12-24-2014, 12:34 PM   #107
Tech Adept
 
Join Date: Mar 2014
Posts: 144
Trader Rating: 1 (100%+)
Default

Quote:
Originally Posted by howardcano View Post
One useful thing about kV is it will let you calculate pretty close to the correct rollout for a new motor if you already have found the best rollout for a known motor with a known kV. Just multiply the known motor's rollout by known_motor_kV/new_motor_kV to give the rollout for the new motor.
Howard, this will seem like a silly question but you say you can re-calculate the "rollout" by calculating using the KV numbers. My question is does this also apply to FDR numbers?

I only ask, as, I also use both, the G-Force meter and a CE Dyno, and when I use the KV numbers it gives me a very different number than what the CE does. This is applying the calculation that is supplied in the "Little Black Book" by BJG. The KV number suggests a 5 pinion change where the LBL calculation suggests a 2 pinion change.

This is supported on the track as well, so I'm just wondering if there is a difference in RO versus FDR numbers?

Since I'm on the topic of Dynos, another interesting thing I've noticed is when running motors on upper timing settings, the motors seem to act a little different at the mid 8 to mid 9 amp loaded draw settings, this is also noticed when doing a inline no load test on the motors. Yet when the motor is at a lower timing setting it doesn't get the same "kick" feeling.

Also if your going to try to eliminate the bigger hard components (speed control) for a neater intermediate controller such as the ORCA BMD unit, I have found that this only works in lower amp draw applications, thus lower RPM as well. I only found this out as I was testing one motor and kept changing timing settings, but the RPM readings would never change during the dyno runs. But as soon as I went back to my test mule speed control changes began to show up again.

I also have been looking at sensor board variances. Since I'm using only one brand of motor, out of the 12 motors I've tested, the phase differences have been a best of 1 to 3 and the worst was 5. The 5 motor actually struggled to make good power and seemed to run warm. I changed out the sensor board on this one and it really woke up the motor.

Too bad about the Novak Sentry being discontinued. Glad I kept mine. Hard to believe that they where blowing them out for the fully loaded models for around 20 bucks. I think some of the guys have played with the Eagle Tree units, but no much talk about them either.
Rodney Racer is offline   Reply With Quote
Old 12-24-2014, 02:01 PM   #108
Tech Elite
 
howardcano's Avatar
 
Join Date: Jan 2012
Location: Olathe, KS
Posts: 3,278
Trader Rating: 35 (100%+)
Default

Quote:
Originally Posted by Rodney Racer View Post
Howard, this will seem like a silly question but you say you can re-calculate the "rollout" by calculating using the KV numbers. My question is does this also apply to FDR numbers?

I only ask, as, I also use both, the G-Force meter and a CE Dyno, and when I use the KV numbers it gives me a very different number than what the CE does. This is applying the calculation that is supplied in the "Little Black Book" by BJG. The KV number suggests a 5 pinion change where the LBL calculation suggests a 2 pinion change.

This is supported on the track as well, so I'm just wondering if there is a difference in RO versus FDR numbers?
I'm not familiar with the "Little Black Book" by BJG, so I can't comment on that. Could you please expound on the calculation (and its rationale) used there?

Yes, rollout and FDR would be affected equally, since FDR is just a simpler way of stating rollout when a fixed tire diameter is used. But keep in mind that FDR varies inversely to rollout, i.e., higher rollout is lower FDR.

The rollout change using kV is a first approximation based on gearing for peak power output, and is better suited to low-power motor/battery combinations. When the motor is thermally-limited-- so one is gearing to not exceed a temperature (rather than for peak power output)-- as is the case for high-power combos, then the calculation will be less valid, since the results are affected very much by the efficiency of the motor.

As you stated, on-track results give the final answer.

By the way, I have been doing some testing on the Analyzer itself, and will post results when done. Oh, and I should mention that delivery from EA was incredibly quick, especially given the holiday season!
__________________
Howard Cano
When race results are re-calculated using the IOF (Index Of Fun), I always win.
1993 ROAR 1/8 Pan National Champion
howardcano is offline   Reply With Quote
Old 12-24-2014, 03:38 PM   #109
Tech Elite
 
CraigMBA's Avatar
 
Join Date: Mar 2003
Location: Valley of the Dirt, CA
Posts: 2,832
Trader Rating: 22 (100%+)
Default

The oval guys have used this datalogger for years:

http://www.eagletreesystems.com/inde...&product_id=54

All the oval dynos are very similar in output readings.
__________________
* Cee Lo Dizzle, the Secizzle * Red Bull * Team Homies * Pintura de Negro Mate * USVTA #152
CraigMBA is offline   Reply With Quote
Old 12-24-2014, 09:39 PM   #110
Tech Addict
 
Join Date: Aug 2008
Location: Floresville, TX
Posts: 747
Default

Quote:
Originally Posted by CraigMBA View Post
The oval guys have used this datalogger for years:

http://www.eagletreesystems.com/inde...&product_id=54

All the oval dynos are very similar in output readings.
Not sure what dynos you are referring to, but the most popular one when I was oval racing was the Fantom dyno and it wasn't and still isn't similar between dynos.

BTW I'm told the eagle tree data logger is really great outside with the GPS feature.
John Wallace2 is offline   Reply With Quote
Old 12-24-2014, 11:04 PM   #111
Tech Elite
 
CraigMBA's Avatar
 
Join Date: Mar 2003
Location: Valley of the Dirt, CA
Posts: 2,832
Trader Rating: 22 (100%+)
Default

Quote:
Originally Posted by John Wallace2 View Post
Not sure what dynos you are referring to, but the most popular one when I was oval racing was the Fantom dyno and it wasn't and still isn't similar between dynos.

BTW I'm told the eagle tree data logger is really great outside with the GPS feature.
I've not seen a Fantom dyno in 20 years.

West Coast Oval guys use a Blazer dyno, Bryan made the first one. This is a copy, but it's got some other features.

http://www.mcpappyracing.com/dyno.php
__________________
* Cee Lo Dizzle, the Secizzle * Red Bull * Team Homies * Pintura de Negro Mate * USVTA #152
CraigMBA is offline   Reply With Quote
Old 12-25-2014, 02:29 PM   #112
Tech Adept
 
Join Date: Mar 2014
Posts: 144
Trader Rating: 1 (100%+)
Default

Quote:
Originally Posted by howardcano View Post
I'm not familiar with the "Little Black Book" by BJG, so I can't comment on that. Could you please expound on the calculation (and its rationale) used there?

Yes, rollout and FDR would be affected equally, since FDR is just a simpler way of stating rollout when a fixed tire diameter is used. But keep in mind that FDR varies inversely to rollout, i.e., higher rollout is lower FDR.
The "Little Black Book" by Big Jim Greenmeyer was pretty much the bible about brushed motor tuning. The information is based on results found using the CE Turbo Dyno. He tried several different dynos and this was the one he ended up using. From that he came up with the same theory as you, once a good known motors FDR was established, the dyno RPM number multiplied by the FDR number and divided by the new unknown motors RPM number could be calculated to get similar on track performance. Very much what you are saying.

Like I stated previously, when I do it with this method, using the DYNO RPM numbers, the re-calculated FDR numbers work. BUT when I use the G-Force KV numbers, the re-calculated FDR number is considerably different, and on track doesn't work. Although the new number is very safe as far as FDR numbers go, I think the performance of the re-calculated FDR suffers on the track.

Of course these are just my findings, but I think the KV number from the G-Force being based on a no load number could be skewing the re-calculation.
Rodney Racer is offline   Reply With Quote
Old 12-25-2014, 04:54 PM   #113
Tech Elite
 
CraigMBA's Avatar
 
Join Date: Mar 2003
Location: Valley of the Dirt, CA
Posts: 2,832
Trader Rating: 22 (100%+)
Default

The loaded chassis dynos like the ones oval guys are awesome for getting your motor package totally sorted out - if you have a powerband limited application like running an oval car.

What road or off-road racers should be looking for is consistency between motors. Sensor boards that are functioning properly and aligned right. Free spin amp draw. Ect.
__________________
* Cee Lo Dizzle, the Secizzle * Red Bull * Team Homies * Pintura de Negro Mate * USVTA #152
CraigMBA is offline   Reply With Quote
Old 12-27-2014, 09:35 PM   #114
Tech Addict
 
Join Date: Aug 2008
Location: Floresville, TX
Posts: 747
Default

Quote:
Originally Posted by CraigMBA View Post
I've not seen a Fantom dyno in 20 years.

West Coast Oval guys use a Blazer dyno, Bryan made the first one. This is a copy, but it's got some other features.

http://www.mcpappyracing.com/dyno.php
I saw that one when I was looking for a dyno. Too many pieces to put together and too easy to have my son send me the Fantom sitting in his attic. Just had to buy new software that worked on Windows. Greg Green made a chassis dyno years ago, but having one set up with sensors and connected to a computer to get FANTOM like dyno data is a great way to go.
John Wallace2 is offline   Reply With Quote
Old 12-27-2014, 09:45 PM   #115
Tech Addict
 
Join Date: Aug 2008
Location: Floresville, TX
Posts: 747
Default

Quote:
Originally Posted by Rodney Racer View Post
The "Little Black Book" by Big Jim Greenmeyer was pretty much the bible about brushed motor tuning. The information is based on results found using the CE Turbo Dyno. He tried several different dynos and this was the one he ended up using. From that he came up with the same theory as you, once a good known motors FDR was established, the dyno RPM number multiplied by the FDR number and divided by the new unknown motors RPM number could be calculated to get similar on track performance. Very much what you are saying.

Like I stated previously, when I do it with this method, using the DYNO RPM numbers, the re-calculated FDR numbers work. BUT when I use the G-Force KV numbers, the re-calculated FDR number is considerably different, and on track doesn't work. Although the new number is very safe as far as FDR numbers go, I think the performance of the re-calculated FDR suffers on the track.

Of course these are just my findings, but I think the KV number from the G-Force being based on a no load number could be skewing the re-calculation.
I'm surprised that any no load values would work. Since I don't have a chassis dyno, I use the next best thing- my car on the track (or the street in front of my house) and take the RPM numbers from the ESC. These RPM numbers work well to come up with a FDR for a different motor to get similar performance.

While the Little Black Book certainly provided a lot of tricks for getting brushed motors to scream, not all of them were legal for ROAR sanctions races.
John Wallace2 is offline   Reply With Quote
Old 01-01-2015, 04:23 PM   #116
Tech Adept
 
Join Date: Sep 2001
Location: Cali
Posts: 185
Trader Rating: 1 (100%+)
Default

Quote:
Originally Posted by godzukihop View Post
Just got my GFORCE MOTOR analyer and have been playing around with it, but had a few questions. Can anyone advise on good or max #'s for amp draw, RPM, timing and noise. I am in need of help with a 25.5 Novak for VTA.
Any advice on ballpark numbers? I'm really wondering on the amp draw as that seems to be independent of the others.
damo is offline   Reply With Quote
Old 01-02-2015, 03:48 AM   #117
Tech Master
 
EDWARD2003's Avatar
 
Join Date: Jan 2003
Location: Kagoshima, Japan
Posts: 1,918
Trader Rating: 6 (100%+)
Default

I would say, anything higher than 4.0 amps then you're wasting valuable power
into heat. A 2.0 ~ 4.0 range is a good range in my opinion.

The motor dynoed is a Speed Passion MMM 21.5 with a stock rotor and a green timing board. Nice dyno results indeed
Attached Thumbnails
G-Force Motor Checker-image.jpg  

Last edited by EDWARD2003; 01-02-2015 at 06:09 AM.
EDWARD2003 is offline   Reply With Quote
Old 01-02-2015, 05:31 AM   #118
Tech Fanatic
 
Join Date: Feb 2014
Location: Kirkland, WA
Posts: 871
Trader Rating: 6 (100%+)
Default

Quote:
Originally Posted by EDWARD2003 View Post
I would say, anything higher than 4.0 amps then you're covering valuable power
into heat. A 2.0 ~ 4.0 range is a good range in my opinion.
Wow that's a nice motor there. Is that a novak 25.5? 12.3 rotor?
__________________
-Mike B.
Carnage9270 is online now   Reply With Quote
Old 01-02-2015, 06:10 AM   #119
Tech Master
 
EDWARD2003's Avatar
 
Join Date: Jan 2003
Location: Kagoshima, Japan
Posts: 1,918
Trader Rating: 6 (100%+)
Default

Speed Passion MMM 21.5 with stock rotor and green timing board.
EDWARD2003 is offline   Reply With Quote
Old 01-09-2015, 06:12 AM   #120
Tech Elite
 
howardcano's Avatar
 
Join Date: Jan 2012
Location: Olathe, KS
Posts: 3,278
Trader Rating: 35 (100%+)
Default

As promised, here are some observations on the GForce Motor Analyzer:

First, some photos of the circuit board:





The power jack is screwed to the side panel for support, which makes it more rugged-- a nice feature. The sensor jack is through-hole, which is much more rugged than surface-mount. (I have broken a surface-mounted sensor jack off the circuit board on at least one ESC I used to own!)

The microprocessor is a C8051F410, apparently using its internal oscillator (specified at 2% accuracy). It has an on-chip 12-bit ADC (4096 counts).

The Analyzer measures sensor board timing while running in sensorless mode, but kV in sensored mode, so any timing adjustments made on the motor will be reflected in the kV measurement.

I compared readings from the Analyzer with my own tachometer and voltmeter (both with much better accuracy than the Analyzer, and with NIST-traceable calibration). Here they are:

Reference GF Analyzer Difference
26970 RPM 26530 RPM 1.6%
8.13V 7.9V 2.8%
3317 kV 3422 kV 3.2%

The manual claims a kV accuracy of 3%, and my results are pretty much in line with that. None of the measured accuracies are good enough to compare readings from one Analyzer to another, except only as "ballpark" values. When comparing motor readings, using only one particular Analyzer will give more meaningful conclusions.

It is disappointing that the voltage readings have a resolution of only 0.1V (84 total counts), as the microprocessor is certainly capable of reading to 0.01V. But to be fair, there is no spec for voltage resolution and accuracy in the manual. Ditto for the current measurement, which could easily go to two decimal places.

The RPM (and therefore kV) readings are quite noisy, and require some "eyeball averaging" to get a reasonable result. This was in stark contrast to the tachometer that I normally use; it dithered only +/-30RPM (which is its resolution) during a simultaneous measurement. It would also have been nice to have more accuracy on the RPM measurement, and adding the required crystal or resonator to clock the microprocessor would have added little to the cost. But again, there is no spec for RPM accuracy in the manual.

For me, all of the above is just secondary functionality; I already have the necessary equipment to accurately perform these measurements. My main use for the Analyzer is to measure sensor timing with a minimum of fuss. Here are the Analyzer readings compared to those calculated from measurements made with my oscilloscope (which has much greater accuracy than the Analyzer), with the motor set to 30 degrees (per the Analyzer average display):

Oscilloscope Analyzer
Sensor A 29.0 29
Sensor B 30.5 29
Sensor C 29.2 31

The manual gives a specification for timing accuracy as "+/-4%", which is vague at best. Is this 4% of the displayed value, 4% of 360 degrees, or something else? Fortunately, the measured accuracy (at least for the test, above) is quite good, and definitely better than my eyes can read some little hash marks on an endbell (which may not be very accurate, either).

The timing check takes a bit of time, so one can't make real-time adjustments to set a motor to a desired point. It's an iterative process. Real-time measurement would be nice, but considering the number of simultaneous measurements and number of calculations required, and considering the low price of the Analyzer, I can accept the tradeoff. The best part is it is much simpler and quicker to use than other methods available to me. I like it!
__________________
Howard Cano
When race results are re-calculated using the IOF (Index Of Fun), I always win.
1993 ROAR 1/8 Pan National Champion
howardcano is offline   Reply With Quote
Reply



Currently Active Users Viewing This Thread: 2 (1 members and 1 guests)
fordohio
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 10:41 AM.


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

SEO by vBSEO 3.5.0