Ran across this article on a HiMax review, indicating some yaw stability concerns.  Ultimately mitigated by adding a dorsal fin or a turtle deck.

http://www.lightaircraftassociation.co.uk/2012/Magazine/April/HiMax.pdf

Any HiMax flyers run across this before, or is it really not an issue?

I cannot speak specifically to yaw stability in the Hi-Max in terms of adequacy.  However I can mention that when you have "wrap around windows" instead of a fastback a great many designs have found they needed to add a low fin, often called a "rake", forward of the vertical fin to which the rudder is attached.  

There was also a very interesting NASA report translated from a French study, NASA TTF-17, 446, which tested spin resistance and recovery for various fuselage section shapes.  You can find a copy of this on the Internet.  If you have trouble and want a copy, I can private message or email attach a PDF file of it, for anyone who wants one.  The most spin resistant fuselage shape turns out to be rounded on the bottom and square edged on the top.  This works well with a type like the Hi-Max in that you can build a fastback version in which the wings fair into the top squared off edges and if you want you could add a small rounded fairing on the bottom of the fuselage.

So there are really two solutions, if indeed one finds there is a problem, either just add a "rake" forward of the vertical fin, or go with a fastback version.

Tom

Many years ago met a HiMax flyer who had a crash upon landing. He believed that the cabin structure blanked out the rudder on final.

I wonder if some Vortex generators would help with the airflow. (until one gets the turtle-deck completed).

This is something I never experienced with my Hi Max. I built one in 91 and found it to be a great flyer, straight and true in all aspects. I have built 3 mini max and a hi max.  One Mini Max had a 503 and weighed 325 pounds and the hi Max had a 503 and also weighed 325 pounds, the one thing I noticed with the same power and weight was that the hi Max stall speed was lower.  I assume that’s because of the added 2 feet of airfoil lift created over the cockpit. The stall speed in the hi Max was about 30 mph and this was tested numerous times and even next to another airplane to confirm. The mini max of equal weight had a stall speed of about 34 mph.
This was the Hi Max model 1700.
Great Fun...

Jim

My observation with my hi-max is that upon landing rudder effectiveness is nearly non-existant without a blast of power.

Jimwing,
Did you go with the plans version of the aft fuselage, or a fast-back?

Ironnerd,
I followed the plans 100%.  I was a dealer at the time so it was important that I stuck with the plans. I’ve flown a bunch of mini maxes and the best flying in my opinion are the ones that follow Wayne’s ideas as close as  possible.

Quoted from Jimwing

Ironnerd,
I followed the plans 100%.  I was a dealer at the time so it was important that I stuck with the plans. I’ve flown a bunch of mini maxes and the best flying in my opinion are the ones that follow Wayne’s ideas as close as  possible.

Weird how that works...  

Thanks. You just got my plane in the air about a year faster.