Stinson 108-3 Voyager (oz14354)

About this Plan

Stinson 108-3 Voyager. Radio control scale model, for electric power with Speed 400 motor.

Quote: "Sport scale electric, for geared Speed 400 power. Stinson 109-3 Voyager, by Pat Tritle.

For many years, I've had a soft spot for scale 1/2A R/C airplanes. The problem was trying to keep one of those temperamental oil-dripping little buggers running long enough to get a good flight.

Well, not long ago, Craig Wagner of Aerocraft Models approached me about designing a series of Texaco Class airplanes for Speed 400 electrics. I've been designing airplanes for a long time but my experience with electrics was limited to the kitchen can opener, so I figured a crash course in things electric was in orde. I read all the magazine articles I could find and spent many hours discussing parameters with my good friend, Gary Kyle. I soon came to realize that, with the off-the-shelf equipment available nowadays, building a 300 sq in airplane under 20 oz with six cells was not going to be that difficult.

Much of my modeling experience has been in rubber free-flight so the designs really went back to the roots. Since electrics are clean and virtually free of vibration, the airframe didn't have to be overbuilt to survive, which lends itself well to a very strong and very light model.

The Stinson Voyager seemed like the perfect subject for the project. So, I ran the numbers at a 48 inch span to achieve the goal of around 300 sq in wing area and the proportions were great. The horizontal stab was increased 10%, the vertical fin was reduced 10%, and the movable rudder was increased 40%. I reduced the fuselage cabin width by one inch and shortened the nose by 3/4 in. Don't worry though, the overall Stinson look was not lost and up until now, no one has even noticed the changes and, boy - does it fly! Of the ten geared Speed 400 designs over the last two years, the 48 in Stinson is still my favorite for weekend sport flying. It's honest and stable but has a really 'spunky' feel.

For thermal duration, my 60 in Stinson is hard to beat. With the wing loading around 6-1/2 oz/sq ft, it'll go right up even in very light lift and at that size is still visible at high altitudes. That model is being considered for a possible construction article later on, if we get enough requests for it.

Construction: Hand-selecting and weighing each stick isn't necessary for building a good weekend sport flier but, for a seriously lightweight model, contest grade balsa should be selected. The 48 in Stinson was built using off the shelf aircraft balsa and flew at 17.9 oz on six cells, 18.6 oz on seven. Either way, performance is quite good and you can shoot landings for almost ten minutes. I personally like the performance better on six cells, as I prefer a lighter wing loading.

Tail Section: Start by making up the bowing patterns from cardboard or artists' foam board, and laminate the outlines. When dry, remove the bows from the form and build the stab using the wood sizes shown. When building the vertical fin and rudder, shim the leading and trailing edges as shown. Remove from the plans and sand to an airfoil shape.

Remove the horizontal stab from the plans and sand the edges round. Hinge the rudder and elevator using 1/8 wide sections ef Radio South hinges. Don't glue the hinges in until final assembly.

Wings: Cut the bowing patterns and build up the wingtip bows. Cut the wing ribs from light 1/16 sheet wood and the dihedral braces from 1/8 lite ply. Starting with the center section, glue the upper and lower center section spars to the dihedral braces as shown. Cut the sheeting and assemble the center section over the plans..."

Direct submission to Outerzone.

Scan by MarkD, cleanup by Circlip.

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