Hello Philip,

A couple of thoughts...

What prop are you using? Many of my friends use very low pitch props with their hover planes.

How is your lateral balance?

The firewall looks to have a bit of right thrust already in it. Check to see that your engine thrust line is perpendicular to the firewall. If you inadvertently canted it to the left it may have counteracted the right thrust in the firewall.

Good luck,

-Michael