Trouble shooting help needed with iosd data log

Pumpkinguy

Member
I have been having a hell of a time with my hex build I started in December.

I will be as brief as possible.

1100 hexacrafter, A2, kde 4215-465, 75+ esc, Tmotor 17" props. Aircraft 8kg

I have been testing with various props and payloads and she has been running great.

Last week I tested with a 6.5kg payload. AUW of 14.5kg.

480 seconds into the flight she shuttered in the air a bit. Like a big gust of wind hit her only there was no wind. She then started into a slow yaw clockwise. Like she would if she lost a rotor only all 6 appeared to be running fine. I immediately landed. I took off the payload and brought her up in the sky again. Yaw was gone. Back to flying great.
Here is the data log. https://www.dropbox.com/s/f661obey86romn7/FLY053.DAT?dl=0
And a screen shot of the area in question. I have enlarged the yaw so you could see when it takes place. View attachment 24625
Another screen shot when it was flying great. Is it normal for 1, 3 and 5 to have a slightly different output than 2, 4 and 6? The graph is like a mirror image. View attachment 24626

Thanks
 

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Pumpkinguy

Member
Common folks. Please help a brother out. Lots of wicked smart guys here. Do I need to start mailing out cases of beer?
 

Hexacrafter

Manufacturer
Pumpkin
This is an easy one. Frame tuning motor alignment. It is very easy with our frame and permanent unlike round arms with clamp on mounts. There are two ways to do it, the more labor intensive is on our website under pro tips. The easy way is to shim the mounts. Please call me and I will walk you through it. Thanks. Andrew
 

Pumpkinguy

Member
Pumpkin
This is an easy one. Frame tuning motor alignment. It is very easy with our frame and permanent unlike round arms with clamp on mounts. There are two ways to do it, the more labor intensive is on our website under pro tips. The easy way is to shim the mounts. Please call me and I will walk you through it. Thanks. Andrew

I can always count on you andrew. I've watched kloners video on alignment. You suspect that will cure my second question but do you have any idea about the main issue?
 

Hexacrafter

Manufacturer
The difference in CW vs CCW motor amps is due to the misalignment. Most would never notice the degree of misalignment in our frames as it is usually less than 0.1 degree out of the box. Hence you are not having the traditional issues that most with round tubes have where misalignments of 1.0 degree are common where the CCW or CW motors will come down hot with the others cool. Additionally, at 0.1 degree it flies awesome. But there are those who like the added efficiency that comes with perfect alignment.... longer flight time as the motors do not have to work as hard. So some spend the extra time to "tune" the frame to "perfect". The advantage is, once it is done, it is fixed forever.... no rotational clamps to misalign.
As far are the loss of yaw authority, to the extent you describe, no .... I do not believe you can attribute this to the slight misalignment you obviously have.
I have seen the loss of yaw authority with a more severe misalignment and a severely underpowered aircraft, but it will usually be a HARD 90 degree yaw when hit by a strong gust of wind. It was more like a right or left face for you military guys. Not a continual yaw rotation.
Did you happen to check the motors/ ESC for higher temps..... this sounds to be more like a motor bearing starting to go or some other mechanical motor/ ESC issue, but honestly it is really hard to know without more information. Based on the graph, I do not like the look of #2 at 485. #5 also at the same time, but #2 is really weird....

I hope this helps.
 

Pumpkinguy

Member
Esc temps were good. 115-120f
Motors were 140 ish. #2 and # 5 were 170-177f.

I was thinking bearings. They feel good and have low hours. Actually less than 2 hours but they do have a crash. It's possible once they heat up they bind, reducing rpm thus giving the symptoms of a motor loss.
I noticed they are just standard nmb brand (China) and they have standard clearance. "C3" rating would give them a tad more internal clearance for use with higher temps.
I just priced out new bearings. I refuse to put Chinese back in. Top tier like NSK will cost me $200.
 

hjls3

Member
Hey buddy - given you are using one of andrews frames i doubt this is the issue - however, thought id mention - way back when the s800 first came out and i was dumb enough to be early adopter...i had that weird 90 degree yaw on occasion and tracked it down to vibes getting to the IMU - again - doubt that is your issue but thought id mention.
 


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