I don't recall any plans with my mayhem just some hand written sketches and some typed out written instruct's pretty basic stuff.
There are several plane's out there that are very close to the Mayhem but unfortunately all of them are arf type models too.
As far as i can see the easiest way to get some plans is to get some masking paper and some good straight edges and a tri square and start to work.
Honest it will take longer to make the plane than the plane.