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Old Dec 10, 2012, 09:22 PM
Teddy Ong
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Wow that sounds serious. And did you follow all the instructions in the book? I have no idea. It could be: Battery problem. (Have you found the same thing on other models)
2.ESC (the 45a seems large enough. Did you forget the heat sink? Or a bad solder joint of something?
3. Motor (faulty motor? Not the right one? Drawing too much power? A faulty one?)
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Old Dec 10, 2012, 10:12 PM
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Originally Posted by flybyjohn View Post
This was a turnigy trust 45a with sbec that never seemed to get hot before. Has anyone had a problem with a esc like this before. I am new to electric flight and I don't know where to start. Could it be the motor or motor wires that caused this or am I just looking at a new esc and call it good? My motor wires are 16 gauge.
The Trusts are my ESC of choice and I've not had an issue with them before, however, you still need to consider that it is a very cheap ESC (and from Hobbyking) so you will occasionally get a dud one. Personally I'd just check the motor and all of the wiring that you can see to make sure there wasnt a short somewhere, get a new ESC and see how she goes. It does sound to me like it was the ESC was playing up, not a wiring, battery or motor issue.

Well done on the deadsticks BTW, a polaris with a 2200 mah is reasoanbly heavy and can be a handful to land smoothly without power.
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Old Dec 10, 2012, 10:42 PM
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I have had about 7 trouble free flights and after that sometimes when I plugged the esc in, it would take sometimes up to 7-10 seconds for the motor to start beeping the startup process which was longer than normal. This thing where it got stuck at half to full throttle confused me and the only way to turn it off was to disconnect the battery. I did spray this esc down with corrosion x before use and so that may have had an effect on it but not sure. I thought corrosion x was safe for esc's.
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Old Dec 10, 2012, 10:48 PM
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Joined Jul 2008
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On my XL when I am above half throttle all is fine.
But if I drop below, the motor will cut out intermittently. If it does, a quick shot of power will get it moving again.
Corroded connectors? Bad solder joints? Esc timing?
Need to get her ready for snow!
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Old Dec 11, 2012, 12:16 AM
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Melbourne, Australia
Joined Apr 2009
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Originally Posted by flybyjohn View Post
I have had about 7 trouble free flights and after that sometimes when I plugged the esc in, it would take sometimes up to 7-10 seconds for the motor to start beeping the startup process which was longer than normal. This thing where it got stuck at half to full throttle confused me and the only way to turn it off was to disconnect the battery. I did spray this esc down with corrosion x before use and so that may have had an effect on it but not sure. I thought corrosion x was safe for esc's.
CorrosionX is fine, sounds like the ESC overheated for some reason. I suspect a bad solder joint on one of the phases or simply the ESC is a dud. Back when Pushlaris was young it used to go all quiet then I'd get the startup tones and all would come good for a bit. The problem was that if I didn't retard the throttle during this restart the ESC would note the throttle's current position and call it FULL and when I brought the throttle back to zero that was ZERO. The ESC was a Grayson 30A with a linear BEC on board and it simply wasn't good enough. 40A switching BEC ESC is a minimum in my books.

Yours sounds like the opposite problem but a problem in and around the ESC regardless. Do some elimination fault finding and reflow the solder joints if that's possible. Otherwise go for a straight out ESC swap.

What cooling system do you have for the ESC?
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Old Dec 11, 2012, 12:25 AM
Aus
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If you've let the magic smoke out, I would suspect it is dead. To confirm, can you see any burn marks on the ESC? If you've still got the heat shrink on the ESC you may have to remove it to have a good look at it. If there are any burn marks, I would throw it out and get a new one. 40/45 Amp is a good size and worth purchasing a spare or two if you are able. Good luck and I hope you get airborne again very soon.
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Old Dec 11, 2012, 07:32 AM
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I have plastic spoon scoops front and rear for cooling and have been flying in temps below 40 deg F. The capacitors sticking out of the end look like they could be swelled a bit. I have left the shrink wrap on just in case hobbyking will warranty it. I have another one on the way, had to cancel an order that was just about to be shipped just to add another esc to it so I wouldn't have to pay for the extra shipping on one esc. It was odd that two times the motor just quit in the air and then when testing on the ground it was like the motor forgot where low throttle was and wouldn't shut off.
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Old Dec 11, 2012, 07:36 AM
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United States, TX, Kingsland
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Originally Posted by flybyjohn View Post
I actually had a dead stick landing after about 2 minutes of flight on the 2200 pack. It glided down nicely and I landed very smooth. the sbec was working as I had all control surfaces working but the throttle did not work. I unplugged the battery and replugged it and it took a few extra seconds to play the motor tunes and it fired up again so I put it back in the air for about 45 seconds and the throttle died agian. Another deadstick but all goes well.
Up to this point, it sounds like a classic case of low voltage cutoff. Did you check the pack for individual cell voltage under load at this point? You can hook up a volt meter or a volt watch to the balance lead of the battery and power up the motor to check on the battery individual cell performance under load. Sometimes a cell will drop voltage under load.

You also didn't mention the temperature of the packs when you were flying. Lipos don't like to fly when they are cold. They should be kept at about body temperature before flying in cold weather. I keep mine in an inside shirt pocket under my coat in cold weather.

McD
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Old Dec 11, 2012, 09:24 AM
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The packs temp was above 40 deg F as the outside temp was this and the battery was in the car for 1 hour prior to flying and the car was warmer than outside. I did not check the under load current of the battery, the pack was however just charged and balanced. I did plug in a second pack when I got home and had the same symptoms so I think the battery was not at fault. I am a little concerned about something else being wrong that caused this problem like motor wires to motor or motor itself. I may just replace the motor extension wires from 16ga. to 14ga. to make sure that I don't fry another esc right off the bat.

Another thing is I do use a foam ear plug to reduce the front scoop intake area in colder weather so that the battery doesn't get too cold when flying below freezing. Battery always feels warm after about 5 minutes of flight.

What would cause the speed control to jump to half throttle in the off position to wide open throttle in the full on position while it was currently being run? Could this be a timing issue or a short somewhere, in wires or motor?
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Old Dec 11, 2012, 10:53 AM
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Canada, ON, Ottawa
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Originally Posted by bob93447 View Post
The Model Aero heat sink works very well and is easy to install. I put one on my 100% Polaris with no vents. I've done 12 minute flights with no problems using a 2200 mah battery and the esc is barely warm at the end of the flight.

Bob
I agree. Heat sinks work well and they don't need to be huge.

It's surprising how little exposure to outside air is needed to keep an ESC within the safe temperature range. Either a heat sink or even a fairly small flow of air through the fuselage will prevent the steady build-up of heat you get with a sealed hull.

By the way, there's no harm in the ESC getting fairly warm. As long as you can touch it comfortably immediately after flight, it's not too hot. The problem comes if you have an uncooled ESC that's OK for 5 minutes but keeps on getting hotter and you fly for 7 or 8 (or 12) minutes. I originally flew Polaris with sealed hull and let things cool between flights, but it was a nuisance and a constant worry. Ever since I've used either vents or a heat sink.

One more point. The maximum ESC heating occurs not at full throttle but somewhere in the middle of the throttle range. So it's no use saying "I'll fly gently and it will stay cool."

Battery heating, by contrast, increases rapidly at high throttle. You can't do much to cool a battery in flight as the heat can't escape fast enough. So the answer is to use batteries with the ability to deliver the current without straining. I always figure to use a battery at about half or two thirds its rated current for long life. A 2200 20C will theoretically deliver 44A but I don't normally run them over about 25-30A (and well under that in Polaris). A 1500 20C is theoretically good for 30A but I don't run them at more than about 20A. I'm also very careful about not running a 3s battery below 11.1v (resting voltage, measured after landing). As a result, my batteries last a long time. I have several that have had four seasons of extensive use and a couple that are five years old. I ALWAYS time flights and check voltages.

The other thing about battery temp is to keep them cool before use. (Except in our part of the world, where right now the problem is to keep them warm!)
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Last edited by Daedalus66; Dec 11, 2012 at 11:27 AM.
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Old Dec 11, 2012, 11:32 AM
59 years of RC flying
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Originally Posted by flybyjohn View Post
Has anyone found that in high speed fast rate multiple rolls, the polaris gets "off balance" or starts to look like a snap roll? I don't know exactly what happened but on about the 3-4th roll, instead of looking like a football spiral, it was a real wobbler. Two in a row look great. It got so bad that it took a few seconds falling to recover, I had plenty of altitude to correct. I also found out that it will track perfectly in an outside loop but does not track well at all in an inside loop.
Sounds like just running out of speed in the rolls. If the speed is kept up the Polaris will roll indefinitely. But of course, the Polaris is not an ideal design for precision aerobatics. With all that weight and area up top it's never going to do truly axial rolls. I find the AquaJet does better in such maneuvers.

As for the tracking issue, it's not an inherent characteristic as far as I can see but something about your setup. My current Polaris (which is not very true after numerous repairs) can be trimmed to track well through a reasonably large inside loop but then corkscrews in an outside. Very tight loops, either way are not precise.
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Old Dec 11, 2012, 11:42 AM
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Originally Posted by Jeffrey Matthews View Post
I want to build the 133% version and does it need the k2 or k4 foils? Does someone have the plans for these foils and are willing to share them with me?

One other question, will the Grayson hobby supermega motor fly this well?

Incisal
The Polaris doesn't need anything other than a flat plate airfoil. It flies great at any size from 75% to 150% with just one layer of 6mm Depron.

The motor should be fine. It has high KV so probably needs about 7x5 prop.
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Old Dec 11, 2012, 11:57 AM
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Originally Posted by flybyjohn View Post
I have had about 7 trouble free flights and after that sometimes when I plugged the esc in, it would take sometimes up to 7-10 seconds for the motor to start beeping the startup process which was longer than normal. This thing where it got stuck at half to full throttle confused me and the only way to turn it off was to disconnect the battery. I did spray this esc down with corrosion x before use and so that may have had an effect on it but not sure. I thought corrosion x was safe for esc's.
ESCs do fail. I saw or heard about several incidents of roughly this kind during the past season at our club field. The initial behavior was classic overheating -- let it cool and it works again. But as long as the ESC had decent cooling, the overheating was abnormal and a symptom of something else amiss inside the ESC.

A further sign that it's an ESC problem is that it wouldn't shut down.

It's highly unlikely that the wires, battery, CorrosionX, etc were to blame. The wires at 16g are more than big enough -- I often use 18g. Anyway, they would not cause the problems you had. Nor would the battery (cold batteries just don't put out). It's clearly time for a new ESC.
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Last edited by Daedalus66; Dec 11, 2012 at 12:07 PM.
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Old Dec 11, 2012, 12:02 PM
59 years of RC flying
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Originally Posted by AeroRecon View Post
On my XL when I am above half throttle all is fine.
But if I drop below, the motor will cut out intermittently. If it does, a quick shot of power will get it moving again.
Corroded connectors? Bad solder joints? Esc timing?
Need to get her ready for snow!
One way or another it's likely an issue of an ESC that's faulty or doesn't match the motor. I would experiment with timing and if that doesn't do it, go to a different ESC.
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Old Dec 11, 2012, 12:52 PM
When pigs fly rc
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Any new news on the ultra? Can't wait for a video...
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