The next step called out in the instructions involves sanding the entire horizontal tail assembly. It helps to remember that “sanding” in this case involves two different jobs…shaping, and smoothing. Shaping comes first, and it can be scary if the plans don’t show exactly what the finished part is supposed to look like. In the case of this Stinson, they do…you just have to study the drawings until you’re sure you understand every detail.
This part is important, and I’ll say it again in the future. The biggest mistake new model builders make when sanding to shape is failing to take off enough material…leaving lumps and bumps, or sort-of-round edges when they should be neatly radiused. The trick is to take your time, and don’t quit until it’s as good as you can make it.
Shaping the stabilizer and elevator leading edges and tip to blend smoothly together. I have pinned and taped the two parts together in their finished position, and used the plan drawing to confirm exactly what material needs to be removed. Always use a sanding block for jobs like this.
Here's the same tip assembly with all the surfaces and outside edges sanded to shape and blended together. I used a long, straight block and 320 grit paper to get to this stage, where the structure is ready for covering.
According to the plans the trailing edge of the stabilizer should be squared off and the leading edge of the elevator should be wedge shaped. The model will fly OK this way, but that's not what the control surface gap on the full scale SR-9 looks like.
On the full scale Stinson, the stabilizer trailing edge and the elevator leading edge are both round-section steel tubing. This is one of the things that makes building SCALE model airplanes interesting...the model plans are not always accurate in terms of scale accuracy, and is is up to YOU to get things like this right.
I made a compromise here. In order to replicate the round trailing and leading edge cross sections accurately it would be necessary to make significant design changes in the entire horizontal tail assembly. If I intended to use this model in TOP GUN level competition I would do just that, but as it is going to be a sport-scale model to fly for my own enjoyment that extra work would not be justified. What I HAVE done is to radius the surface edges enough to give the impression of round tubing structure beneath the covering.