Tightening up my downwind turns?

I was out flying today in approximately 50kph winds - at least that is the differential between my upwind and downwind ground speeds. I’m trying to get my wing tuned to fly a tight survey grid. I flew a couple different grids with different lead-ins. Waypoint radius is 10m.

My upwind turns are nice and tight, in fact they are overshooting my lead-in waypoint but lining up nicely with my actual grid.

Downwind turns, on the other hand, wash way out resulting in missing almost the entire pass.

I have set my LIM_ROLL_CD max bank angle to 60 degrees, confirmed that I can bank at 60 degrees in FBWA, but the plane is not exceeding 45-50 degrees in AUTO.

I increased PTCH2SRV_RLL to 1.25 with good results as it was initially not applying enough yank in the “bank and yank” to cut a tight turn. I also significantly decreased the rudder mix as it was pulling so much differential brake that it was dropping the nose.

Is this just NAVL1_PERIOD being too high at 15? I’ve never set it below 15 before so was hesitant to decrease it further. This is an 80" flying wing and my first Arduplane delta. I can still fly this plane far more aggressively in MANUAL than in any auto mode.

Logs attached - they cut off mid flight, an eternal problem. Most of the time it works, sometimes an entire mapping flight is wasted. Tried different SD cards, it’s a problem for another day…

I use a wing for mapping as well. Tight turns are an issue. I’d suggest trying the option in Mission Planner to do every other lane in one direction and then the other lanes on the way back. That way you have a lot more room to make the turns.

Lower your Nav L1 period. I run 9. That should allow the 60-degree turn easily. If you reduce your max bank angle, you may have quite a bit of overshoot. L1 period and LIM_ROLL_CD go hand-in-hand and are inversely related.

Further note about mapping… always turn into the wind if possible for the reason you are talking about. On a windless day, my aircraft can achieve about a 35m turn diameter at 18m/s and 60-deg LIM_ROLL_CD. I use a 35m waypoint radius and the turn stays as a full bank all of the way around to 180-degrees with minimal overshoot of the next flight line.

Thanks guys, I usually use alternate lanes while mapping. I was flying with no alternation just to test my turning radius here. Still, sometimes I have issues turning tight enough for alternate lanes when the wind is blowing. Which is almost always, as this is Saskatchewan, Canada.

I usually try to work out a grid that I can work upwind, but the wind shifts so rapidly here that what I’d really like is to get everything tuned tight enough that I can handle any wind.

I have never quite understood the relation between waypoint radius and turning radius. It seems wider waypoint radius also results in more sweeping turns for some reason - but also more probability of passing wide on waypoints when the wind is blowing.

I usually run long lead-outs and short lead-ins to allow my plane to come around and line up. Unfortunately, that means Mission Planner as QGroundControl doesn’t support adjusting lead-ins. What I’d really like is one of the grid planners to have an option to set waypoints at the peak of the turn, rather than both ends and trusting the bank angle to line up. It often seems the plane turns too tight or too wide as it aims for the end of the lane, resulting in over/undershoots.

Either that or an option to plan tight turns like you would fly them manually - by initially turning the opposite direction to allow room for the bank.

I will tighten up NAVL1 and see if I get my bank angles, at least.