First flight using 3.1 a couple of concerns

Over the New Years holiday I was able to test out my FW550 with the new AC3.1.
Previously I was running I think 2.6 and had problems with it. This new 3.1 is soo much better than the previous FW. The alt hold, loiter, drift and RTL worked really well. I did have a couple of anomalies though.
The RTL was fantastic. It would consistently land within inches of its takeoff point.
However, first interesting thing. I made quite a few flights and executed the RTL just for fun. At one point the battery had run low and it went into the RTL routine on its own. However, on subsequent flights, it would not initiate RTL upon low battery. The only thing that I know was different was that the first time it happened (initiated RTL) I had a 4s 5000 battery on board. The other flight where it wouldn’t go to RTL on its own I was running a 3s 5000 battery. I was using an external voltage annunciator and it was sqealing but the copter didn’t RTL. The last flight it was a ways out and it started descending. I tried to recover in stabilize mode but it kept descending. I switched to RTL and it just kept descending until it hit the ground. It popped the landing gear and brushless gimbal off the frame.

Any ideas?

At another time while flying in Alt Hold mode abt 6 feet above ground. As I flew it away from me it started to descend. I let it go to see if it would recover. I finally stopped it when it was abt a foot off the ground.

The last little bug was after several flights I landed, put in a new battery and took off. It would start to twitch like it was trying to bank to the right. It would do this several times then stop. It was in stabilize mode at the time.

Has anyone else seen these little things?

All in all it is a lot better than it used to be. Thanks to the Devs for all of their work. I was ready to scrap the APM for a KK2.1 board. Now I’ll keep the APM.

[color=#00bf00]Please refer to the instructions on how to use this forum![/color]
Without a logfile, nobody will be able to analyze your problem.

Sent from my Ainol Novo 7 Fire using Tapatalk

[quote=“StefanG”][color=#00bf00]Please refer to the instructions on how to use this forum![/color]
Without a logfile, nobody will be able to analyze your problem.

Hi Stefan,

I show 16 logs. Which ones should I send?

Heres the log file from the last flight where it didnt go into RTL upon low voltage.

Thanks for looking at this.


Hi Don !

-Battery Failsafe Problem:
Did you rhink of changing the “trigger voltage” different when moving form 3S to 4S ?
If not that would be an easy fix :slight_smile:

-Alt Hold descending:
Did you see the loads of posts on how to correctly shield the Barometer from unwanted pressure changes such as pressure bubbles and prop wash ?
(Not sure if that is the reason for your specific problem but it greatly helped MY Alt Hold behaviour)

best post is here:

I used the last method and its perfect…

-angle after switching batteries:
An easy explanation would be that the new battery was not properly attached and shifted back and forth, are you sure that its not something easy like that ?



Thanks Ender,

I did not change the settings and I wondered if that was an issue.
As far as the alt hold goes, the APM is mounted on the top of the 550 in its case. It is not an exposed board.
I’d thought it would be fine it’s its original case.
As far as the twitch goes. That’s another good point. There isn’t a good place to mount batteries on the thing. Especially since the cg changes depending upon the size of battery. I usually Velcro strap them. They appear to be tight but that’s something to review.

Thanks for the input.