[NSRCA-discussion] Braking question

Tue Mar 1 16:42:34 AKST 2016

Most modern ESCs use dynamic timing….based on how the motor is responding to the ESC, the ESC adjusts the timing.  In the case of Castle ESCs, using low timing does not specifically limit the amount of timing advance (max is typically 24 degrees), but it makes the ESC more cautious / conservative about advancing the timing.  With other ESCs, setting them to 15 or 20 degrees is typically limiting them to a maximum advance of the specified number, but they are still using dynamic timing.

In practice, set the ESC for the timing recommended.  Running milder timing MAY slightly reduce power, improve efficiency, and drop operating temperatures.  Running more advanced timing MAY slightly increase power and increase operating temperatures.  With the modern ESCs and brushless motors, the differences are rarely substantial.  With geared low pole count inrunners (like Neu 1513-xx, Hacker C50-xx), motors with “D” winds are not going to benefit from high timing.  Motors with “Y” winds may show slightly more RPM with advanced timing, but, the power consumption will also increase (likely not as efficient).

Braking….take a motor with the 3 motor wires “bare”.  Spin the motor and note the resistance.  Pinch 2 of the 3 motor leads together and spin the motor again…the resistance will be increased.  This is effectively what the ESC does in brake mode….and the motor has effectively become a generator – if you use an Eagletree data logger you can see the current spike when the brake is engaged – that is current flowing back into the battery.  When the ESC is in “brake” mode, it is “blind” to the rotational position of the motor, so when the brake is disengaged, the ESC has to “restart” the motor, and that is when problems can happen.  If the ESC badly mis-times the motor, it is like a backfire, and it can be strong enough to pitch the prop/spinner loose or off the plane.  In my experience, mis-timing is more likely to occur when higher brake percentages are used – the more current generated by the motor, the more “noise” there is to confuse the ESC, and the noise does not dissipate as quickly.

I’ve run brake setups on Castle, OS, and Jeti (Mezon).  In my experience, all can mis-time the motor on a restart (after the brake was engaged).  With Castle ESCs, no delay, medium or fast ramp, and 30% brake strength is what I run on just about everything….and it is very rare to have a mis-timing on restart.  On the OS, I found about 50-60% brake provided the same downline braking as the Castle at 30%, and at values over 80%, mis-timing could occur.  Depending on the prop used, and the drag of the plane, some setups can use (and benefit) from slightly higher brake settings.  On smaller motors (<40 sized), substantially more brake strength can be used, to the point that the prop is rotating so slowly that the plane actually starts to speed up in a downline.  The effective brake strength is greater with geared motors, and higher pole count motors.

On Brenner’s V4 contra, the combination of the high pole count Kontronik Pyro and the 7:1 gearing of the Contra results in very strong braking – I had to drop the Castle brake strength to 15% to keep the props spinning fast enough to provide maximum downline braking.  With the Mezon on the V4, 26% brake provided the same downline braking as the Castle at 15%, however, I was getting mis-starts until I dropped the brake strength to 16% - mis-start meaning the throttle would simply fail to respond after a downline with the brake on – sometimes it would throttle up after a brief delay, or after .5 – 1.0 seconds, or after cycling the throttle stick.

I’ve only run 1 sample of the OS ESC and 1 sample of the Mezon, so I consider those data points less definitive (~50 flights each) than Castle (1,000s of flights).

Regards,

Dave Lockhart

Team Castle Creations

From: NSRCA-discussion [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of John Pavlick via NSRCA-discussion
Sent: Tuesday, March 01, 2016 4:52 PM
To: 'General pattern discussion' <nsrca-discussion at lists.nsrca.org>
Subject: Re: [NSRCA-discussion] Braking question

This is my first year flying electric. I DO have an Eagletree logger and I plan on taking some measurements with it when I set up my VF3-E. I’ll share any data with you guys that I think might be meaningful.

John Pavlick

Cell: 203-417-4971

Integrated Development Services

From: NSRCA-discussion [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of David Harmon via NSRCA-discussion
Sent: Tuesday, March 01, 2016 4:28 PM
To: 'John Fuqua'; 'General pattern discussion'
Subject: Re: [NSRCA-discussion] Braking question

Hi John….

I have flown the same motor, ESC and batteries in the same airplane trying to determine of there is any noticeable difference in the air and I cannot tell any difference.

Perhaps a timed ground run at partial throttle could determine how much MAH is used from the same battery if the test was repeated at various timing settings.

That would be interesting to see how that turns out.

I have used the same equipment at I believe 24 and 20 degrees as well and I could not determine any difference.

Perhaps any performance change would only be seen at full throttle…but then…we almost never use full throttle.

An Eagletree unit might be needed to really look into this.

Does anyone have any test data on varying the timing on these motors??

David Harmon

Sperry, OK

From: John Fuqua [mailto:johnfuqua at embarqmail.com] 
Sent: Tuesday, March 1, 2016 2:11 PM
To: 'David Harmon' <k6xyz at sbcglobal.net <mailto:k6xyz at sbcglobal.net> >; 'General pattern discussion' <nsrca-discussion at lists.nsrca.org <mailto:nsrca-discussion at lists.nsrca.org> >
Subject: RE: [NSRCA-discussion] Braking question

David

We have been running the Pletty at 20 degrees timing.   Can you tell me if there is any difference in performance?

John

From: NSRCA-discussion [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of David Harmon via NSRCA-discussion
Sent: Tuesday, March 01, 2016 12:35 PM
To: jpavlick at idseng.com <mailto:jpavlick at idseng.com> ; 'John Pavlick'; 'General pattern discussion'
Subject: Re: [NSRCA-discussion] Braking question

Hi John….could be but the OS 1100HV and Futaba MC 9100A work great without screeching or any other operational problems.

The brake is very effective and I have had the brake setting adjusted between 50 and 90 on various 2 and 3 blade props as large as a Mejzlik 22 x 12 2 blade and Mejzlik and Falcon 3 blades.

The hand held ‘loader’ is small enough to put into the transmitter case and you can make quick changes at the field between flights without a computer or other hardware.

Both ESC are clones to each other…they look exactly alike except for the mfgrs sticker.

The loader is also clone across both mfgrs and operationally are exactly alike….in fact I have only one loader and use it on both ESC.

All available at RC Japan….tower does not have them anymore because they said sales was too slow…arrgh

I am using the Plettenberg Advance motors at 15 degrees timing.

73

David Harmon

K6XYZ

Sperry, OK

From: NSRCA-discussion [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of John Pavlick via NSRCA-discussion
Sent: Tuesday, March 1, 2016 12:19 PM
To: 'General pattern discussion' <nsrca-discussion at lists.nsrca.org <mailto:nsrca-discussion at lists.nsrca.org> >
Subject: Re: [NSRCA-discussion] Braking question

The reason this is so touchy BTW is because you guys are using sensor-less brushless motors. Commutation takes place in the speed control. This works fairly well when the speed controller is driving the motor. When it’s the other way around however – not so much. I bet if someone came out with a motor that had position sensors and a really expensive speed controller to drive it, more people would get  interested in Pattern again… LOL

John Pavlick

Cell: 203-417-4971

Integrated Development Services

From: NSRCA-discussion [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of David Harmon via NSRCA-discussion
Sent: Tuesday, March 01, 2016 10:28 AM
To: 'Jon Lowe'; 'General pattern discussion'; 'Jamie'
Subject: Re: [NSRCA-discussion] Braking question

This is exactly my experience as well.

David Harmon

Sperry, OK

From: NSRCA-discussion [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Jon Lowe via NSRCA-discussion
Sent: Tuesday, March 1, 2016 7:48 AM
To: Jamie <jstrong49923 at gmail.com <mailto:jstrong49923 at gmail.com> >; NSRCA <nsrca-discussion at lists.nsrca.org <mailto:nsrca-discussion at lists.nsrca.org> >
Subject: Re: [NSRCA-discussion] Braking question

ESC dependent. Castle ESC braking doesn't work well over 30% in my experience, without screeching. I set my OS controller at 65%, and it works fine. Jason goes as high as 90% with an OS. Some other controllers don't work well with braking at all, such as the YEP controllers from HobbyKing.

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