Ted...thanks for the reply....appreciate your time.
The reason for selecting the "Imitation" with the radial mount nose, was to have a plane capable of easily using a variety of different engines, to include 2-stoke,4-stoke, and possibly electric.
One of these engines is a ST46 which I believe requires 5+oz of fuel, and the battery packs are rather long, so I would prefer not to cut 1" off the nose which would reduce the tank compartment.
Would it be an acceptable alternative to lengthen the tail instead? The fuselage is already built, and it would be an easy operation to graft on 1",2", or 3" of fuselage, and then move the tail assembly back a corresponding amount. What would be the correct amount?
Warren, I think you'd be better off to leave the tail as is and accept a little higher wingloading with the engines that need to be mounted further ahead. You'll note the plans show a hatch in the back for adding tail weight. That's where I put it when I flew the original with the four stroke. Brett's ship flies OK with the longer moments but you'll note his last three airplanes didn't copy the idea.
I think you might be better off to sheet the tail to increase its rigidity and add a bit more built in tail weight, leaving the moments as is. I would couple that with the earlier suggestion to increase the span of the tail to get the total area up around 25%, which will give even greater flexibility in terms of acceptable CG range
As to stiffening the rear of the fuselage, I have several options, including 0.5 oz. carbon fiber, 1/64" plywood, and 3/4 oz. fiberglass cloth, as you suggested. I'm in the process of making test samples of these three material to try and get a more objective idea of their relative characteristics.
With the length of the tail the plywood still scares me. I'd still prefer to see the aft fuse "ovalled" as much as possible and covered with something reasonably rigid like 3/4oz fiber glass applied with the minimum amount of thinned epoxy.