I had my RV-10's first flight yesterday, and thought I'd share something interesting that occurred, mostly as a discussion point: My trim did not work in flight.
System: G3X controlled AP, fronted by a VPX Pro, wiring setup as per them and Garmin.
I tested the system on the ground multiple times, and also had another person sanity check my results. This is my first "electric trim" aircraft, having flown a 182 for the past decade and having built an RV-8 with manual trim. A few days ago I realized I had an error: I had the up and down trim buttons on the control sticks reversed - the more forward button should be "down" trim, I had it as "up" trim.
Not a problem, the VPX has a control for both "normal" and "inverse". As well, the G3x configuration mode system also lets you change between a normal and reverse setting. Whew, I can just change this setting and I don't have to fix my wiring, great.
Swapping the VPX value, I checked the system again, and it functioned as expected.
First flight is here, and one of my sage pilot friends suggests I have a little nose-up trim for takeoff since I'm fairly forward CG on the flight, it'll help a bit with getting off the ground. Ok, on my checklist I go ahead and take his advice and do that - trim system move and responds as expected. Trim is now slightly nose up.
Takeoff, everything is great, but man that climb is a bit aggressive - need a lot of forward stick to overcome that trim. No problem, attempt to trim nose down - and nothing happens. Multiple attempts, no movement. I can see the g3x screen indicator for trim turn from white to blue every time I push the trim button, but it is most definitely not moving. This is becoming a problem, I'm pushing really hard to keep relatively level if not modest climb. Nothing is working though. Luckily I had a chase plane to help with traffic and tower while I debugging. Tried the copilot stick - same results. Went into the VPX screen on my MFD and attempted to the push trim up/down from there, same results. It was getting the signal, but not moving the servo. Meanwhile I'm pushing extremely hard with my left arm.
Ended up circling back and coming in - luckily with less power and after applying flaps, the nose up trim was in a pretty good spot to make a nice landing. Luckily I didn't have any other major issues on that flight to deal with, as my attention was 100% focused on this problem.
Taxied back, and while doing so exercised the trim - and it worked fine!
First thought was maybe we had it on a really slow movement setting at airspeed, but checked the g3x config settings against my chase plane's equivalent, and they were basically the same. Also thought maybe something was just binding it up and airspeed pressure was just too strong to overcome, but putting pressure on it manually with our hands, it would still move fine.
I ended up going into the VPX configuration and changing normal back to inverse as it was before. Flew again, and this time it worked fine (albeit, the buttons on the stick were backwards). Used that as an opportunity to just rewire the sticks the correct way, and on a later flight verified it's working as expected.
Why this was an issue: I dunno! Why it worked on the ground but not in the air: I dunno! I suspect there is some kind of vpx/g3x logic that kicked in with airspeed at which they were fighting with each other and neutraling out the command, but that's just a pure guess.
Food for thought.
System: G3X controlled AP, fronted by a VPX Pro, wiring setup as per them and Garmin.
I tested the system on the ground multiple times, and also had another person sanity check my results. This is my first "electric trim" aircraft, having flown a 182 for the past decade and having built an RV-8 with manual trim. A few days ago I realized I had an error: I had the up and down trim buttons on the control sticks reversed - the more forward button should be "down" trim, I had it as "up" trim.
Not a problem, the VPX has a control for both "normal" and "inverse". As well, the G3x configuration mode system also lets you change between a normal and reverse setting. Whew, I can just change this setting and I don't have to fix my wiring, great.
Swapping the VPX value, I checked the system again, and it functioned as expected.
First flight is here, and one of my sage pilot friends suggests I have a little nose-up trim for takeoff since I'm fairly forward CG on the flight, it'll help a bit with getting off the ground. Ok, on my checklist I go ahead and take his advice and do that - trim system move and responds as expected. Trim is now slightly nose up.
Takeoff, everything is great, but man that climb is a bit aggressive - need a lot of forward stick to overcome that trim. No problem, attempt to trim nose down - and nothing happens. Multiple attempts, no movement. I can see the g3x screen indicator for trim turn from white to blue every time I push the trim button, but it is most definitely not moving. This is becoming a problem, I'm pushing really hard to keep relatively level if not modest climb. Nothing is working though. Luckily I had a chase plane to help with traffic and tower while I debugging. Tried the copilot stick - same results. Went into the VPX screen on my MFD and attempted to the push trim up/down from there, same results. It was getting the signal, but not moving the servo. Meanwhile I'm pushing extremely hard with my left arm.
Ended up circling back and coming in - luckily with less power and after applying flaps, the nose up trim was in a pretty good spot to make a nice landing. Luckily I didn't have any other major issues on that flight to deal with, as my attention was 100% focused on this problem.
Taxied back, and while doing so exercised the trim - and it worked fine!
First thought was maybe we had it on a really slow movement setting at airspeed, but checked the g3x config settings against my chase plane's equivalent, and they were basically the same. Also thought maybe something was just binding it up and airspeed pressure was just too strong to overcome, but putting pressure on it manually with our hands, it would still move fine.
I ended up going into the VPX configuration and changing normal back to inverse as it was before. Flew again, and this time it worked fine (albeit, the buttons on the stick were backwards). Used that as an opportunity to just rewire the sticks the correct way, and on a later flight verified it's working as expected.
Why this was an issue: I dunno! Why it worked on the ground but not in the air: I dunno! I suspect there is some kind of vpx/g3x logic that kicked in with airspeed at which they were fighting with each other and neutraling out the command, but that's just a pure guess.
Food for thought.