Tern-V (oz16943)

About this Plan

Tern-V. Free flight towline glider model. Wingspan 72 in.

Uses Ritz wing construction.

Quote: "TERN-V Towline Glider. Through 1957 and 58, I worked hard to develop an all-weather Nordic towline glider that would have good still-air duration, and yet could stand up under the worst punishment that Old Man Weather could dish out. By the end of 1958 the test program was nearly complete. The model would do about 2:45 in calm air, and adjusted for turbulent air, it would ride out nearly any wind. Best of all, it would thermal at the drop of a hat, and never seemed more in its own element than when it was tearing around crazily in a tight circle riding some really turbulent thermal air.

I won the 1958 King Orange Contest with this model, and since then it has won 14 straight firsts, including the 1959 Central States Semi Finals for an International team place. It has never been beaten in any contest. Of course it will be, but so far it sure has a doozer of a record. The only two Nordic contests I lost during these two years was when I foolishly flew my 'Continental' design in air that was just too rough for it.

In the 1959 FAI Semi-finals, there was a gale of about 40 mph, and I think that of all the flyers I was the only one that didn't bust a wing (although I did break a new 25 lb towline). I attribute this mainly to the sparless non-rigid construction in which I ute only the leading and trailing edges a la 'Ritz wing' as I have been doing for many years. On some of the tows the wings flexed to about 90° dihedral (some of the flyers swore the tips nearly touched) but the construction held up without trouble.

Since the fuselage is the base to which all the components are attached, let's start by gluing this important structure together. Select some hard 1/4 in sheet 48 in long and cut 2 pieces for the top and bottom 1/2 in wide tapered to 1/4 wide, with the taper starting 14 in from the front. The backbone is cut of rock-hard 1/4 in stock to 1/2 in width x 14 in long. Glue this in place, centering it between the top and bottom strips. Now glue and pin the front 14 inches of the fuselage together, binding with 1/8 rubber to make sure all joints are tight.

When thoroughly dry, glue and pin the rest of the fuselage, again binding with rubber for tight joints. When binding, use two strands spiraling in opposite directions, so that your fuselage will not be twisted. Align the fuselage carefully and set aside to dry. You will need to mount the wing tongue and tow bar before you go any further on the fuselage, so get them ready.

The wing tongue is cut and filed from .072 aluminum 75 ST. Bend the 28° dihedral in the center of the tongue before cutting out the centers and tapping the mounting holes. The tow bar is made out of a 3/16 x 1/4 strip of magnesium or soft aluminum. The holes are bored and tapped - be careful to maintain exact 1/4 in centers so that the tow hook will fit in any position.

Fit the wing tongue onto the fuselage, using a base of hard balsa trimmed to fit the dihedral and give the 4° incidence. This block is glued on top of the fuselage. The tow bar is recessed into the bottom of the fuselage, holes for the tongue mounting screws are drilled through the backbone, and the tow bar and tongue are fastened into place with the mounting screws..."

Direct submission to Outerzone.

Supplementary file notes

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