Canterbury Sailplanes: F-20 Tigershark

Model Airplane News, Nov 2003 by Bogenschild, Norm

CANTERBURY SAILPLANES F-20 TIGERSHARK Scale sourer with striking appeal!

If I had to choose one word to summarize the Canterbury Sailplanes F-20 slope glider, it would be "striking." Its aggressive look and smooth flight characteristics make this plane a joy to own and fly. The F-20 is easy enough for a beginner to fly, but it will still hold the interest of experienced pilots.

The EPP-foam kit was easy to assemble and has proven to be extremely durable. Some combat action put the plane's durability to the test, and it came out completely unscathed!

KIT CONTENTS

When I opened the box, I was pleasantly surprised that almost everything needed to build the plane is included. The 16-page instruction manual is very complete but lacks illustrations that would have been very helpful in a few key steps. A separate diagram shows the radio installation.

The majority of the aircraft is constructed of precision-cut EPP foam. The fuselage comes in four pieces-two cut to the outline of the side view and two cut in the shape of the intake ducts.

The EPP wing-cores come with precut spar reliefs that are some of the best I've seen. The package also includes four fiberglass wing spars and aluminum spar joiners. The precut tail surfaces are constructed of Corflute material, and the cuts are all very clean and uniform. The hardware package contains everything you need to complete the F-20.

ASSEMBLY

Wings. Following the instructions, I started with the wing. I glued the two wing-cores together using 3M 77 spray adhesive and joined the two sets of fiberglass spars with the prebent aluminum joiners and the supplied glue. The angles of the prebent joiners needed a slight adjustment to fit properly, so I bent them to the correct angle using pliers.

Although the wing-cores come precut for the spars, you must remove additional material in the center of the wings to accommodate the aluminum joiners. I have found that by installing a paper clip in the tip of my electric soldering iron, I can form a foam-cutting tool in a number of different shapes. I used my improvised foam cutter to relieve the center of the wing.

After I had test-fit the spars and ensured that everything was flush, I glued the spars into the cores following the instructions. They must be allowed to dry for 24 hours before any more work can be done.

Next, I applied the nylon-reinforced strapping tape to the wing according to the pattern on the outline drawing. I then covered the wings with Top Flite EconoCote. I chose this material in place of the provided red packing tape because it provides a much nicer finish and is specifically designed to be applied at low temperatures.

I cut the ailerons to length and then covered and attached them using a strip of covering material; this is very similar to the suggested method outlined in the instruction booklet. At this point, I set the wings aside to begin construction of the fuselage.

Fuselage. To assemble the fuselage, I first glued the two center sections together and applied a strip of nylon-reinforced strapping tape to each side. This allowed me to shape the center section. I used a wood rasp and some 80-grit sandpaper to round the edges and create the F-20's smooth contours. The directions suggest that you do this with a hobby knife, but I don't recommend that; it's too easy to cut off more than you bargained for.

After I had shaped the center of the fuselage, I installed all the radio gear. This was out of sequence, but had I followed the instructions, 1 would have had to cut through the covering material to install the gear.

I glued the two intake ducts to the sides of the fuselage and carefully sanded them into shape. Then I applied the nylon tape to the entire fuselage according to the instructions. I used a hot covering iron to smooth the tape over the compound curves and applied EconoCote covering over the nylon tape to produce the finish shown. Black automotive pin-striping tape separates the red and white color scheme.

During the covering process, I accidentally melted a small section of the canopy by allowing my covering iron to become too hot. To repair it, I removed the affected material, applied some spackling putty then reshaped and recovered the damaged area.

Tail surfaces. The tail surfaces come precut from Corflute material. The vertical fin was white and the horizontal stabilizer was red, but the color scheme I desired required the vertical fin to be mostly red. Because Corflute cannot withstand the temperatures required for iron-on covering to adhere, I used a sheet of self-adhesive covering material from Top Flite that matched the color of the EconoCote to make the vertical fin red. The horizontal stabilizer and elevator required little more than installation of the provided hardware. I glued both tail surfaces to the fuselage using the supplied Bostik glue.

Radio installation. The F-20 requires only a 2-channel radio to operate the ailerons and the elevator; I chose the glider version of the Hitec Flash 5 computer radio because I wanted to try its flaperon function with the F-20. The package includes three microservos, a mini Hitec 555 receiver, a power switch and a 27OmAh flight pack.