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Dec 14, 2002, 09:08 PM
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Ben74's Avatar
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Logo 20 crashes again - ESC failure.


grr. my logo 20 crashed again today, this time due to the failure of the schulze 35ho speed control. a few minutes into the second flight of the day, the motor suddenly stopped with no warning. i was about 80 feet up, but i did not realize what was happening until i had already lost about 30 feet. i tried to auto in the last 50 ft, but couldn't get the head speed up enough before she hit the ground. i did have radio control the whole time, so i was able to hit flat on the skids, but there was a boom strike, which resulted in a broken boom, and a few small plastic parts lost. blades look ok. upon inspection, we found that the ESC was much hotter than usual. normally, it barely even gets warm after a full flight, but this time it was pretty toasty. the pletti seemed abnormally hot as well. the batteries were ejected upon impact, so i don't think the heat was built up due to a stalled motor after the crash. the esc smelled slightly burnt though. the motor still turns freely, so i doesn't look like it threw a magnet or anything.

when i got the heli home, i removed the tail, blades, and flybar, and tried to see if the esc was still working. i got some strange results. first, i plugged in a 24 cell pack. the motor twitched slightly after i connected the pack, then nothing. no arming beeps, no LED. the esc did start to get warm though. so i disconnected the battery, and disconnected the motor from the esc. next i plugged in a 12 cell pack. the LED came on this time, but moving the thottle switch, did not change the LED. i was puzzled. so i unplugged the 12 cell pack, plugged the motor back in and plugged the 24 cell pack in again. this time, there were arming beeps, but the esc immediately began to smoke. i disconnected the battery right away. so it looks like the ESC is a loss.

i can't understand why this happened. i haven't changed anything on the heli recently. the esc never got hot before, i so didn't think it was being pushed too hard. it's only rated for 35A continuous, 45A peak, but a lot of people use this esc on their logo 20s without problems. about 10 seconds before the motor stopped in flight, i had done 4 consecutive flips. i've done this before without a problem though. i wonder if the current during those flips was just too much for the esc. the esc has over current protection though, so if there was too much current going thru it, it should have shut down during the flips, not afterward. it could have shut down due to over temp, but if that were the case, i'd expect the esc to still function ok.

i bought this esc with the heli from a previous owner. i don't know how old it is, and i don't have the receipt. i hope schulze will replace it, or give me a good deal on a new one. i'm not sure if i want to buy another schulze after this though.
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Dec 14, 2002, 09:12 PM
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Ben74's Avatar
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btw, i don't think this was a case of the dreaded ESD. there was no flash and no popping sound. rain was forecast for this weekend, so the air was very humid today too.
Dec 14, 2002, 09:53 PM
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What is your throttle percentage Ben?

I have a theory, if your are doing heavy aerobatics like you are with an ESC with a slightly marginal amp rating you should not run under 80% governor setting.
Dec 14, 2002, 09:59 PM
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Ben74's Avatar
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it's at 83%
Dec 14, 2002, 10:57 PM
1.21 Gigawatts!
Steph280's Avatar
Arg! Not another crash! Sean had his Schulze 45Ho cut out on his Logo last weekend as well.

What timing mode was your ESC set to?

Motormike also warned me about running below 80% throttle.

Hope you'll have it back soon.

Stephen
Dec 15, 2002, 02:21 AM
-Flight enthusiast_
gpeden's Avatar
Hi Ben,

Sorry to hear this news. Crashes close together like this really stings, I know. I hope that you get it back in the air soon......

FYI, I had my Future 35Ho shut down in flight (overheating I think) for a few moments after some hard flying at sea level (for a change) on a hot day this summer. It restarted during the autorotation. Your ESC's shutdown sounds like a failure of some sort as you suggest.

Do you think that your ESC could have been damaged from the earlier crash? The reason that I ask is that after I experienced the 3rd bad crash in 4 flights in 2001, I reviewed the "mental video tape" a bit and realized that although I thought that I was trying to regain orientation and control as the heli plummeted, I was instead trying to fly a heli that should have been autoed because it had lost almost all power under load as I pulled out from inverted with a half loop. I feel that The ESC had been damaged in the earlier crashes and finally died when pressed to full capacity.

I am presently flying the same ESC after repair and software upgrade and certainly am pressing it harder with the 100/70 rotor head and the 28mm increase in rotor diameter it gives. It will be interesting to try it at sea level in Chilliwack this May, especially if the weather is hot.

All the best during this sad time,,,,

Glen
Dec 15, 2002, 04:30 AM
My 35Ho with the Pletti motor on 24 cells and the 9 tooth pinion overheated and SPLIT the shrink tubing a few months back! It was 90 degrees outside and I was hovering at 75%.

Re-shrunk the ESC, and all is well. I now fly 85% all the time. With the cooler temps, the ESC is running cooler than ever.

BUT, the Pletti motor and 24 cells is REALLY pushing the 35Ho to the MAX! Mark Mercer (Mikado/RC direct sponsored pilot who lives in San Diego) told me that his ESC tended to overheat and shut down all the time. He added a 5 volt cooling fan on top of the heatsinks, plugged into a spare channel on the Rx, and it keeps the ESC MUCH cooler. Im installing one this week!

Gary Wright had his 35Ho fail as well. He was using the B50-14XL motor though and 20 cells at 95% govenror I believe. He has since switched to the new Hacker Master HM-H48-3POPTO heli ESC. It is rated for 10-30 cells, 48 amps continuous and a much higher surge than that. Gary doesnt seem to have any problems with this ESC yet!

I have one of these ESCs on hand for my Raptor 50 conversion. Since it can handle so many more amps continuous, Im thinking of ordering another to use in the Logo 20. The 35Ho is certainly an EXCELLENT ESC, but maybe when using 24 cells we are pushing it to the max - 8 or 9 tooth pinion.

The new Hacker Mater ESC is about $155 shipped from Aircraft-World.com, or about $175 I believe from Aero-Model in the US. I think this should be your replacement ESC.

Sucks when we crash due to failure. I dont mind pilot error (Well, of course I do to some extent), but when we have no control over it at all, there's no worse feeling.

Jason
Dec 15, 2002, 04:55 AM
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Ben74's Avatar
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yeah, the crash hurts extra bad when it's not your fault. i don't get too upset over crashes though. it's part of the hobby. you have to factor it into your overall costs. it's still worth the enjoyment i get out of it.

i was thinking about going with the hacker master too. seems like a great deal for all those features. i'll probably just order one now, and if i get the schulze fixed or replaced, i'll just sell it. it's apparently cramping my style
Dec 15, 2002, 05:08 AM
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Ben74's Avatar
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hey stephen, why did sean's schulze die? was he able to figure out the cause?
Dec 15, 2002, 05:30 AM
I would highly suggest picking up a Hacker ESC now to use while the Schulze gets repaired. Once it gets back to you it will be as good as new with an upgrade so selling it then would be a good idea. Or just keep it as a back up!

I learned this week that you cant have enough brushless ESCs. I was flying a new motor on an old plane that was pulling 36 amps. It was cutting out my Phoenix 35 after a few seconds so I installed a spare Kontronik 40-6-12 and I was up and flying in the time it took to do some soldering!

From now one I plan to keep 2 of these ESCs on hand as spares. They work for all my e-helis - JR Voyager E, Logo 10, Logo 20 and the Raptor!

Jason
Dec 15, 2002, 11:24 AM
Overall I have been somewhat disappointed with my Schulze 35HO. It doesn't run hot since I use no less than 80% throttle, and I have a cooling fan that directs air on to the motor and ESC. But it is unstable. It has on several occasions for no obvious reasons, lost it's programming and returned to default. It almost always at some time durring the day spontaneously speeds up about 200 RPM when you least expect it. I believe this may occur because of thermal effect on the circuitry. And as has been pointed out repeatedly it is highly susceptable to ESD, as is my 18HE on my Hornet. It shut down once when my anntena touched the carpet it was hovering over.

I finally got a Hacker Master that I ordered 3 weeks ago. We'll see if it solves these problems. the only thing that I can see that is worrisome about them is No Warranty. They are warranteed to work out of the box and that is it. If it is not returned within 7 days of purchase, your screwed.

I haven't tried it yet, but I've heard the Hackers start up harder than a Schulze, which in my opinion are very hard starters. You should see how a Joker starts with an Actro controller. Nice smooth inital start with a steady pulse free build up to the desired speed. The Schulze is unstable here also.

I must stress that my version 35HO is the older software/firmware, supposedly recently upgraded. I don't know if the new units are as bad, but I should because they sold me the old version well after they had released the new one. When I install this Hacker Master I'm going to see if Schulze will make it right and upgrade mine. I'll report the results good or bad.


Al
Dec 15, 2002, 06:47 PM
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ScotY's Avatar
Quote:
Originally posted by Albig
But it is unstable. It has on several occasions for no obvious reasons, lost it's programming and returned to default. It almost always at some time durring the day spontaneously speeds up about 200 RPM when you least expect it. I believe this may occur because of thermal effect on the circuitry. And as has been pointed out repeatedly it is highly susceptable to ESD, as is my 18HE on my Hornet. It shut down once when my anntena touched the carpet it was hovering over.
Funny you should mention this, because my 18He occasionally defaults back to the original settings too! And, it will occasionally speed up in flight as well! Very strange behavior that I have not been able to track down. I am using the 18He in a Hornet with a Hacker motor. I may have a combination of problems as occasionally the motor will shut off in flight, for just a split second, but enough to scare me and lose a bit of altitude. I suspect the BEC in this case but the other problems, the ones that you are experiencing, are probably not related. It's quite humid here so I doubt ESD has anything to do with it, at least for me.

What's this about the Hacker's warranty? Why won't they warrant anything beyond 7 days? I am hoping that the dealers will help with this should a problem arise.
Dec 15, 2002, 07:55 PM
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pgoelz's Avatar
While it has not happened recently, I have had several inflight shutdowns with a Schulze 18be and an AF010 in my Piccolo. Lately, the shutdowns have given way to extremely brief and extremely rare glitches that show up on random channels including the throttle. I never considered ESD. Anyone know what the possibility is of an ESD buildup on a beltless heli? The symptoms fit.

And yes, my 18be also very rarely reverts to default programming.

Paul
http://www.pgoelz.com
Dec 16, 2002, 02:19 AM
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ScotY's Avatar
Hi Paul,
When you say "shutdowns", do you mean complete shutdown or just momentary? Can you list the equipment you are using?
Dec 16, 2002, 07:49 AM
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pgoelz's Avatar
I have had both total shutdowns with accompanying plummet from the sky and momentary throttle glitches. Recently I have also observed an occasional servo twitch.

I am not at all convinced it is a radio issue given the very close receiver / transmitter proximity.

It also NEVER repeats..... not even on the same day. These events are spaced far apart. I sometimes go a month between incidents.

The last one I had was a total shutdown of my Phoenix 25 in my brishless fixed pitch Piccolo.

Before that I have had shutdowns of my Schulze Future 18be in my fixed pitch Piccolo and more recently throttle and servo twitches in the same Piccolo upgraded to collective pitch. All that changed was the rotor system, and the shutdowns stopped and were replaced by milder glitches.

I never considered ESD until now. Maybe the plastic and/or wood rotor can generate enough static to arc through the head and mainshaft to something else?

Paul
http://www.pgoelz.com


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