Kitfox (oz14482)

About this Plan

Kitfox. Radio control sport-scale model, for electric power with geared Astro 15 motor. Wingspan 70 in, wing area 598 sq in.

Quote: "Electric Powered RC Scale. The Kitfox. An attractive, easily built, all-wood model of the popular two-place homebuilt, designed for the Astro 15. By Laddie Mikulasko.

The full-size Kitfox came on the market as a kit in the mid-1980s and has since become a leader in the kitplane business. The demand for it just keeps growing. With its good looks, simple assembly and good flying characteristics, the appeal of this aircraft is not surprising.

When I first saw a picture of the Kitfox I knew I wanted to build a scale model of it, but it was several years before I came across a three-view in the Czechoslovakian model magazine Modelar. Looking at the three-view, I formed a clear picture of how I was going to build it. The only decision I had to make was how large to make the model for an Astro 15 geared electric power system.

For the last several years I have been designing and building models for electric power, and the knowledge I have gained has helped me in determiningwhat will work and what won't. The full-size Kitfox is a cross between an ultralight and a more typical homebuilt, and was designed to be a relatively slow, easy-to-fly, relaxing plane. I wanted to keep these features in the model, so I went with a wingspan of 70 inches - close to the limit for the power available from the Astro 15 geared motor.

The plan was drawn up in short order. I kept an accurate outline on the whole model and tried to design it to be as simple as possible. For this reason the cabin area is sheeted with 1/16 balsa and the cowl is not removable. Access to the motor is through the front opening of the cowl. Again, for the sake of simplicity, access to the motor batteries is from the top, which requires removing the wing. I find this to be no big deal. Undoing the two wing screws and the two wheel collars holding the struts to the fuselage takes less than a minute.

The model went together quickly and easily and was soon ready to be test flown. I did not expect any major problems and got none. The model took off beautifully andclimbed nicely. In the air, the model is stable with all control surfaces being just right.

The rudder is very powerful on takeoff and in the air. The stabilizer and elevator surfaces are relatively small in comparison with the wing, but are more than enough to make the model stable in pitch. The model does very nice loops. The ailerons are sluggish, but are capable of rolling the model.

Because I like to fly in a scale-like manner, I don't like to roll the Kitfox; the full-size aircraft wasn't designed for rolling or flying inverted anyway. As expected, the glide ratio is good and the model can be flown for a considerableperiodof time at a low power setting because of its large wing.

Before you start construction, study the plan. Use the lightest balsa you can find, cut out as many parts as possible beforehand, and drill andcut out lightening holes intheplywood parts as shown. Be sure to use liteply and not regular birch aircraft plywood, it's much heavier!

Wing: Begin by cutting out all of the wingribs. Note that theW1 ribs are shallower than the W2s to allow for the center section sheeting.

The wing is built in two halves, which will be joined later. To build the first half, mark the locations of the ribs on each of the spars. Slide all of the main ribs onto the upper spar. Pin the bottom main spar, rear spar and bottom trailing edge strip to the building board over the plan. Position all oldie ribs and glue them in place. Glue on the top trailing edge strip. Glue in all of the false ribs and the leading edge. Glue on the wingtip and its support gussets. Where shown on the plan, glue in the 1/8 plywood plates that hold the eyes for the wing struts. Punch holes in the ribs and install the aileron Nyrod tube as shown. Sand the wing panel and put it aside.

Build the other half of the wing to the same stage. Before you join the two halves together, pin the center section bottom sheeting to the budding board. Pin the W1 root ribs to the s heeting and the building board. Place the proper size blocks under the wingtips to get the specified dihedral. Glue the plywood and balsa dihedral braces in place. Glue in the two hardwood blocks for the wing bolts. Glue the top sheeting to the cente r of the wing. Mark the location of the wing strut eyes onto the plywood plates and drill the 1/16-inch holes..."

Direct submission to Outerzone.

Scan by MarkD, cleanup by Circlip.

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