Found first issue. A connection in the XT90 kill switch was not sound so could only carry so much power before it maxed out. On the ground the motors pulled more current so they stalled.

There is still a tone from somewhere. I think the ESC but seems ok.

Running up the motors at higher speeds the chain jumped. I need to fit a tensioner, I thought I may need to. I have some ideas.

Also played with the trim. Not really sure what I am doing here but moving channel 1 to the right of centre seems to have aligned the drives a bit better. Once the chain tensioners are fitted I'll give test it on the ground.

Still need to fit the wedge ramp too