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Diagnosis help request

#1
Hi folks! If I missed the obvious location for help requests, please point me in the right direction.
I am having difficulty with my first twin engine plane. I have successfully flown the Explorer, Bushwhacker, and Versa. I am getting the Sea Duck ready and having difficulty with the throttle. When it reaches about 30-40% the port engine starts stuttering badly. It will continue stuttering if I leave it there, or get worse and then stop if I keep increasing the throttle. More info and a summary of my diagnostics in the image.
IMG_20200327_220752723.jpg
 

Hai-Lee

Old and Bold RC PILOT
#2
Did you remember to disconnect the 5 volt wire from one of the escs? As you are playing with 3 ESCs use one as a separate Rx supply and disconnect the red wires from both motor ESCs.

Sometimes the battery voltage/BEC voltage can couple motor generated spikes through to the other ESC and even the Receiver itself.

Just something to try!

Have fun!
 
#3
3 ESCs? There are only two in the build video. I don't understand. Is it possible or desirable to use a third just for the BEC to power the receiver?

I did remove the positive lead from one ESC. The motor seemed to stutter and cut out sooner, perhaps 25% throttle. I will try the other to see what happens.

Thank you.
 

FDS

Well-known member
#4
Have you tried a different motor? Check that you didn’t put a motor screw through a winding. Any motor will do for testing.
Use one ESC with all 3 wires on like normal, that will do the BEC if it’s a decent power level, as long as there aren’t 5 digital metal gear servos on there most up to 3A BEC should be fine, then take the red or + 5v wire out the other esc wire, you always need to do this on twins. You don’t need a third ESc or BEC.
 
#5
I removed the positive wire from the other ESC, and that didn't work either. I removed the positive wire from both ESCs and powered the receiver on the B/VCC port with a separate battery and ESC. One motor just twitched and it's ESC beeped repeatedly while the other acted as if I were cycling the throttle from 0 to 20, back and forth.

I swapped the port and starboard motors earlier, and have independently driven each motor/ESC combo to 95%. They work fine alone, it's only as a twin configuration that I start setting problems. I will double check that I didn't get too close to a winding.
 

quorneng

Well-known member
#7
I can only suggest that you set up the motors , ESC and rx 'on the bench' with short connections. Test them individually and together. With the red wire disconnected from one ESC it should all work. If it doesn't then it is down to substituting one item at a time to find out which it is that is causing the trouble. If both motors work together properly on the bench then there must be something in the connections actually in the plane that is at fault.
It is probably something simple. The tricky bit is finding out what it is.
 

BATTLEAXE

Well-known member
#9
I removed the positive wire from the other ESC, and that didn't work either. I removed the positive wire from both ESCs and powered the receiver on the B/VCC port with a separate battery and ESC. One motor just twitched and it's ESC beeped repeatedly while the other acted as if I were cycling the throttle from 0 to 20, back and forth.

I swapped the port and starboard motors earlier, and have independently driven each motor/ESC combo to 95%. They work fine alone, it's only as a twin configuration that I start setting problems. I will double check that I didn't get too close to a winding.
I am not sure if you done this yet but have you calibrated both ESC's at the same time. I am sure you know both ESC's need to be matching
 
#10
poor solder job at the motor/ESC leads causes a motor to stutter & stop, I have had to resolder the bullet connectors on a few motors and ESC's over the years for similar reacting Motors/ESC issues......... fast elec boats experience this as they get frequently HOT enough to melt the solder joints
I thought it was a bad motor the first time and as I disconnected the bullet connectors to swap out the motor, the wire pulled right out of the bullet.....maybe this is something you could look at .
if you have swapped both the esc and motor its most likely not the issue but you never know..... check them anyways
just a thought
 
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Sero

Well-known member
#12
While it's odd that this happens only on the port motor regardless of which motor ESC you use ( <--- is that correct?) but I have had that same thing happen to me when I throttled up with no prop on. Some ESC's can't figure out the timing when the motor has no load.
 
#14
Update: I took out the electronics to fly other planes for a while. I then went and put the Duck back together to try again. This time it seemed stable up to about 95% throttle. I thought I had done everything exactly the same as the first time and wasn't sure why it worked this time.

I have one theory, and it's pretty much the only thing I did differently. Instead of using extensions for the signal cables from the ESCs to the receiver (they are a tad short on my absolute-cheapest-thing-I-could-find components), I stuck each ESC partly into the wing channel so the signal cable connected directly to the receiver. It might have reduced the cooling to the ESCs somewhat, but the bird flew through two batteries, and man, was it fun!

Looking forward to strapping a glider on top one of these days. Happy flying, all!
 
#15
When she loses all control midair--maybe an ESC overheat or undervolt?--she's a tad heavy dropping to the ground. I was too low to try to glide her down. I wonder if reinforcing the spar is worthwhile. If that's where it broke, then likely reinforcing would only move the break point elsewhere. The nose (bow?) was easily pushed out from the inside and ready to go in seconds.
 

Attachments

cranialrectosis

Well-Known Member
Mentor
#17
Update: I took out the electronics to fly other planes for a while. I then went and put the Duck back together to try again. This time it seemed stable up to about 95% throttle. I thought I had done everything exactly the same as the first time and wasn't sure why it worked this time.

I have one theory, and it's pretty much the only thing I did differently. Instead of using extensions for the signal cables from the ESCs to the receiver (they are a tad short on my absolute-cheapest-thing-I-could-find components), I stuck each ESC partly into the wing channel so the signal cable connected directly to the receiver. It might have reduced the cooling to the ESCs somewhat, but the bird flew through two batteries, and man, was it fun!

Looking forward to strapping a glider on top one of these days. Happy flying, all!

These stories are the best!

Thank you for posting and letting us know that you were able to get this one flying. :)
 
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