An interesting discovery on the box of the imp shows it "suitable for combat" same with the super ring so I built the souper and Barrie is building the imp. Might as well since neither were very suitable for stunt.

In doing so, he's discovered the plans show one control horn for the flaps........it has a tapered trailing edge!
Does anyone know if the functional ones used two horns, as I can't imagine any other way to get operational flaps.

Ken,

You can use "lucky boxes". Search on this site and you will see illustrations of how these work.

I have seen a few and they all used one horn.Don't use two
Ed

the original question seems to have been lost. With a tapered trailing edge and a straight flap horn, if it is bent to accommodate the taper, it will bind, or at the very least provide a very limited range of movement.

OK, it depends on what you call "performance".  The tapered swept forward TE *will* hinder the flap movement.  Lucky boxes help but don't make it great.  Just because Bob Palmer hadn't "invented" the dual horn set up yet doesn't mean you can't use it.

Remember my Freedom 45? It had a single horn and it was impossible fly a competitive pattern, especially in any sustained wind.  The flaps would start binding at about 8~10 degrees and want to spring back to neutral. Two years ago I cut into the turtle deck and replaced the controls with a dual horn set up.   The new set up makes it much better.  Incidentally, Jack Sheeks original plans showed a dual horn set up.  Upon bad advice I didn't follow the plans and paid for it later. The first one died an early death.  The second one is still around.  I don't fly it much but I wouldn't hesitate to take it to a contest.

So, back to the performance issue.  What do you want?  Personally I would put a dual horn in it, but I would fly combat with it