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May 17, 2016, 06:39 PM
Fun until flying robots attack
carcynic's Avatar
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Help!

Lost 2 Planes Due to ESC Failures


I have lost 2 planes due to ESC failures -- Need some advice.

This is what was left after the 5th flight of my E-Flite FJ2 Fury:



... And this happened on the 3rd Pass (Maiden Flight) of my WingsMaker J-11, Converted to an SU-35s:



In both cases, they were 70mm EDF's, with 60A ESC's, and the crash was due to ESC failures.

The FJ-2 Fury fire was due to the ESC, not the battery. The battery was thrown clear, and was not hot or burned at all. It had to be destroyed, however due to impact damage.

I believe the ESC was on fire before impact. I lost thrust, and all control. While I did not see smoke on the way down, one person who witnessed the crash said they did. It was a 100% Factory set up, using the factory E-Flight ESC, but an earlier version than this plane ships with now.

I had checked ESC temperature after almost every flight, and it was warm, but never hot -- certainly not hot enough to cause any worry. The crash happened on the 2nd flight of the day, and after the first flight that day, I did not check the ESC temperature.

---

The SU-35 crash was similar. I realized the plane was slowing, and increased throttle. There was no response. It then jerked or flipped violently, momentarily was in stable inverted flight, and then hit the ground. It as on the 3rd time around the pattern of the maiden flight.

Both ESC BEC's showed obvious failure signs:



This is especially interesting since the 2 ESC's were set up separately. Each was powered from it's own 4S 3200mah 30C battery. Each EDF drew 56A Max (full throttle, full battery.) The BEC in ESC #1 (left engine) drove the receiver and all servos except the NLG Door servo. The BEC in ESC #2 (right engine) drove the Landing gear.

I had planned to run the receiver from a separate BEC, but I never received the 5V/5A BEC I ordered from an eBay seller. I made the decision to connect the Rx to the ESC BEC.

I had retracted the landing gear after take-off, and it operated nominally. It was just after I lowered the landing gear that I noticed a lack of thrust. I lowered the landing gear after only 3 passes specifically so that I could land and check the ESC temperature, battery level and temperature, etc., since this was the maiden flight. It never made it.

I now believe that the ESC's I purchased for the SU-35 are counterfeit HobbyWings.
(See my post in the WM J-11 forum for more details).

I had done numerous ground power-ups for servo installation and setting, and many for landing gear installation, door alignment, etc. I probably did well over a dozen landing gear cycles on the ground. We also did numerous full-throttle motor runs, but no long-duration (full battery) motor run on the ground.

The ESC's were installed in the intake ducts for cooling. (suggested WingsMaker location.)

Upon recovery of the wreckage (several minutes after the crash), the ESC's were hot, but not burning or painful to the touch.

With the exception of not doing a full battery run on the ground of the SU-35s, I feel I have been doing due diligence in building and testing my aircraft. I set them up to avoid things like a stalled retract causing a receiver brown-out.

---

What could cause 2 separate ESC BECs to fail at the same instant, or within seconds of each other?

Am I doing something wrong? Something to cause transients or something else that causes sudden and violent failures of ESCs?

How can I choose good ESC's with out paying $150.00 each? Even if I did pay more would it help? Prices on ESC's vary significantly.

How much current margin do I need? I assumed I would be safe since the motors could never get into the ESC's reserve (80A for 10s advertised, in this case).

The SU-35 is already partially repaired, and while the nose will probably never be 100% straight, and certainly not pretty, it will hopefully fly again. What ESC's do you recommend?
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May 17, 2016, 06:53 PM
http://www.sgvhumane.org/
cmdl's Avatar
Seems like it is the ESC. I have an E-flite 60 A in my warbird, 4s, full throttle 53 A. 2.5A BEC. Does fine with retracts (total 5 ch). I fly full throttle through whole flight on 2200 and 3300 lipos. People will recommend a larger BEC but I'm just pointing out that your BEC specs may have been sufficient (I assume yours were also 5/6ch since you wrote that only nose LG was not driven by the ESC BEC).
Turnigy Plush and Hobbyking brand have worked well for me.
May 17, 2016, 07:20 PM
Retired Electronics Specialist
vollrathd's Avatar

Castle Creations 90 Amp Talon ESC


Quote:
Originally Posted by carcynic
The SU-35 is already partially repaired, and while the nose will probably never be 100% straight, and certainly not pretty, it will hopefully fly again. What ESC's do you recommend?
IMHO, you can't go wrong with the Castle Creations ESC's. They are more $$$$, but with my pile of them, I've only had one failure with some 6 plus years of flying with them. (Connecting reverse polarity to its DC input might have had something to do with it. )

Check out CC's Talon series of ESC's. I've got two of them, their 90 Amp unit, and their 120 Amp HV unit. I'm running the HV unit right up to its maximum 120 Amp rating with no issues. They do have plenty of air cooling. They're pretty much bullet proof.

The 90 Amp unit has a 9 Amp Switch Mode BEC, with a 20 Amp momentary current rating.

Tower Hobbies has them. The CC ESC's come with a voucher for a free CC ESC computer USB programmer.
http://www3.towerhobbies.com/cgi-bin...&I=LXCYNG&P=ML
Last edited by vollrathd; May 17, 2016 at 07:27 PM.


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