I'm a novice with APM and have great difficulty doing what seems to be a walk in the park for most others. I can't get my Skywalker to Fly !
I have spent several days over the last three weeks trying to fly and several nights trying to figure out why it didn't, tweaking and carrying out repairs - thankfully the Skywalker is a tough plane. To explain my problem I will outline the spec, describe what is happening and what I have tried so far.
The Specifaction -
Skywalker 1.68m wingspan.
40A ESC
BEVRC 2814 kv980 motor
APC 9x6 prop
APM with Arduplane 2.28 installed
Main Battery 4S 5000mAH
Second battery for servo and also FPV - 2S - 2.2Ah
The overall weight including the FPV gear is a little above 2Kg (i.e. 2080g). I know this is on the heavy side but I've seen several people flying at about this weight.
What it's doing ......
I have been trying to launch it in stabilize mode and I am launching from hand. I feel I have to give it full throttle or close to full so that it will build up airspeed - if I use less throttle it touches down before building enough speed to fly . The problem is that within about 100m of launch (within a few seconds of launch) the aircraft tends to bank either left or right and rather than correct with the stabalise function it continues to climb a bit but rolls and heads for terra firma. The severity of the decent depends on altitude achieved and if I cut power before it comes down. Although I can see the aerilons trying to bring it back it seems to have no impact on the way the plane flies. Unfortunately the behaviour varies a little so I can't pin point what is happening - e.g. it sometimes banks left and sometimes right. I have tried more than 20 launches while changing many little things and I still seem to get the same..... I'm now pulling my hair out and feeling particularily stupid as I guess it's something obvious.
What I have tried.
In all the pre-flight checks everything seems fine - the aerilons etc respond as they should when still on the ground.
I have adjusted the PID and specifically increased P on the roll so that it might correct more seriously before the plane rolls too far for recovery - no change. I was already using the Skywalker config off the DIY drones site and the P roll is already set to 3 which I think is already very high. I haven't changed anything else on the PIDs from the Skywalker template on DIYDrones.
The trim on the plane is fairly good - I have moved things around a little to make it slightly nose heavy for some attempts and then fairly balanced for others - no noticeable impact. My aerilons, and rudder are trimmed Ok also and generally I have the elevator trimmed slightly up to help with the launch.
On one occasion I did get it up high enough to change to Auto but on that occasion it simply flipped up side down and continued to fly upside down but didn't climb to the assigned waypoint. Because it didn't climb it clipped a tall hedge in the next field and came down. I discovered I had dip switches wrong which had an impact in Auto (i.e. made it fly upside down) - I corrected this but no improvement on the launches haven't managed to get high enough to get into auto again since.
I have always had a well charged main battery and it seems plenty of power. One observation is that the motor seems a little stiff to turn by hand and not sure if it might have taken a knock on a rough landing but seems to run fine when powered up.
I have adjusted the horns on the servos to get more movement on the surfaces but no difference.
As you might imagine my Skywalker is now a little battered but apart from a bit of tape all repairs have been fairly clean and it has kept it's shape. I have a new replacement Slywalker body but don't want to start using it until I figure out what's going on.
I also wondered if I had a problem with the APM (e.g. a faulty sensor) but can't see what and as I said it works Ok in pre flight.
I guess that because of my inexperience I am doing something very silly and basic but for the life of me I can't think what it is - any help / suggestions would be greatly appreciated.
Many thanks
John
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Replies
Hmm, it sounds like we're all having some trouble with our planes not believing in those waypoints. When my team runs hardware-in-the-loop simulations our plane flies fine, so we believe our PIDs are perfect. However, we're having the same issue with physical Auto flight not wanting to go to the waypoints. The difference is that our plane doesn't just go through the waypoints at all. Instead, it decides to fly around in circles for a bit, and progressively decline until we switch to Manual and right the plane (sometimes the throttle cuts out so we end up having an emergency landing).
Our HK Bixler is definitely more beat-up than that. I'm surprised it can fly at all.
First, don't launch in stabilize mode. Launch in manual and only switch to stabilize once you're at a safe height, to tune it. Second, if it's flipping upside down, you almost certainly have your aileron direction reversed. Click the reverse checkbox in the MP RC setup.