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ESC brownout after gyro addition

#21
Looks nice. I'm getting ready to scratch build my 4th Arrow, bringing this one to FliteFest this year. Will be my first trip.
Anyway, you may wanna add some color to your arrow. That solid black is hard to keep orientation, trust me!! Lol Good luck on the maiden.
Good advice. I'm going to attempt a maiden tomorrow I think. Still having a bit of trouble getting the throws symmetric and correct. Having the gyro in the picture makes it a tad more complicated. Strangely was getting preferentially too much left elevon when I pull back straight. Trimming to the right seems to have fixed it mostly.

I took out the Linkage Stoppers because they seemed to stress the control arms too much, but now my default elevon level is too low. Have it trimmed at 100% =/ Guess I need to put the control arms on the next notch and see if that fixes it. Lots of tweaking with this plane before the maiden.
 

kdobson83

Well-known member
#22
Good advice. I'm going to attempt a maiden tomorrow I think. Still having a bit of trouble getting the throws symmetric and correct. Having the gyro in the picture makes it a tad more complicated. Strangely was getting preferentially too much left elevon when I pull back straight. Trimming to the right seems to have fixed it mostly.

I took out the Linkage Stoppers because they seemed to stress the control arms too much, but now my default elevon level is too low. Have it trimmed at 100% =/ Guess I need to put the control arms on the next notch and see if that fixes it. Lots of tweaking with this plane before the maiden.
For more throw you want the control rod farther out on the servo arm and lower down on the control horn. The arrow doesn't need a lot of throw tho, it's fairly touchy on the roll axis.
Just remember, low rates for the maiden. I usually do dual rates. I launch at 50% rates with 30% expo with my 2nd rates up to 75% and expo at 30%. And then once I get a feel for it I dial it in.
 
#23
I've got dual rates set up per the recommended angle card on the plans. Should be good. I was able to fix the trim problem by zeroing out my transmitter trims and letting the A3 adjust the center point trim and do all the elavon mixing.
 
#24
Maiden went well once I got the elavons trimmed right. LOVE the gyro, makes landing and launching in wind a breeze. One bad crash ended the day.
IMG_4252.JPG
 

Brett_N

Well-known member
#25
I just solder a 4S balance plug on my BEC and use the common ground and the 3S (4th pin) for power. That gives me ~12V and draws from all 3 cells. Can run 3S or 4S batteries and not worry.

Also - in planes with a Gyro - the external BEC (I use the hobbyking 5/6V 4A ones) - that goes to the GYRO which powers the servo's. The 2A or 3A from the ESC then goes to the RX. I use S.BUS between my RX and Gyro so there is no power wire anyway.

You CAN run the ESC AND Ext BEC to the RX if you don't have a gyro in the middle. Just make sure both are 5V (some ext BEC's are 5 or 6V) and you have the polarity the same.
 
#26
Hello FT community! Long time reader, first time poster.

I just put together an FT Tiny Trainer with the recommended power pack A, and have had a blast flying it in a local park. It has been amazingly resilient to crashes. The park where I have been flying is located on a large hill that seems to be frequently gusty, so I decided to install an A3 Pro v2 6 axis gyro to give me some more stability on the worst days. Install and setup went smoothly, and I added the included 3300uF/16V capacitor to the bind plug on my OrangeRx r620x receiver to smooth out the BEC voltage. Here's the rundown on the equipment:

  • Motor - EMax - MT1806
  • EMAx BLHeli - 12A
  • Servos - 4x EMax ES9051 5g Servos
  • Gyro - HobbyEagle A3 Pro
  • Battery - Tattu 3s LiPo Battery 75C
  • Receiver - OrangeRx r620x
  • Transmitter - Spektrum dx6 g3

First flight: the plane flew 5 feet and the ESC browned out. Lost communication, and motor cut out. As I approached the plane, I can hear it reconnect as if I've just turned it on. Subsequent flights revealed the same result, all done with the 4 servo setup (sport wing). Dropping the A3 gyro gain to as low as 20% gave the same result at the default servo refresh of 50Hz. If I put the gyro into disable mode it all works normally, no cut-outs. Additionally, with the motor off I can get the ESC to brown out by shaking the gyro in stabilization mode. Moving the capacitor to the various ports on both the gyro and receiver does not fix the issue. The ESC hangs loose in the front of the plane, just behind the motor and is getting plenty of ventilation, and the brown out happens suddenly and early ruling out overheating.

This seems to narrow down the problem to the 1A BEC on the BLHeli. After reading from several well written threads on this forum, I suspect that the 1A BEC is unable to handle the load when all 4 servos are twitching around to compensate for multidirectional wind gusts despite the the capacitor helping. Some have even written that 500mA is probably closer to the capacity this ESC can handle.

Which of these solutions would you recommend:
  • Get a bigger ESC - If this is your rec, which one?
    • BLHeli 20A gets a 2A BEC
    • HobbyKing 40A gets 4A UBEC
    • other option where the rated BEC is closer to reality
  • Get a dedicated BEC and battery - this seems like overkill
  • Get a bigger capacitor - this seems like a bandaid solution to a larger problem
  • Return the A3, noobs shouldn't use a gyro
I'd prefer to actually get this working rather than calling it quits with the gyro, and I hesitant to test the setup much more for fear of damaging my current ESC.

Penny for your thoughts, thanks in advance.
Ben

I have had the same exact behavior with a FR Sky S6R, however interestingly enough it only seems to happen when I use a 3S battery rather than 2S battery on the 12A ESC.

I find this strange because I can even reproduce the brown out when the motor has no throttle when using a 3S battery. I already have a 20 amp flitetest ESC, so I'm going to give that a try. Nevertheless it is good to see this post because I was a bit baffled why this was happening. I actually would expect a 2S battery to have a higher amperage draw at a lower voltage than the 3s battery. And since it worked so well with a 2S battery, I didn't really know what to make of it.

For what it is worth, I decided to use separate channels for the ailerons on my tiny trainer sport wing, rather than a Y-cable so I can have flaperons (which works really well at low speeds.)
 

FDS

Well-known member
#27
If you are using the same propeller with 3s then the extra load is coming from the motor, spinning a large prop slower is more efficient.