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My Riser V-Tail

Here I want to show you my version of the SIG-Riser sailplane.

This year, the idea came up in our club, to organize a competition of the R.E.S. class. R.E.S. stands for “Rudder Elevator Spoiler”. This class for simple 2-meter sailplanes has become extremely popular in Germany. As I wanted to participate in this contest, I had to build an appropriate model. My choice was the “Riser” offered by the SIG company. One reasson for this was the extremely low price for the kit.

The building instructions were straight foreward, so I put the plane together in very short time. When it was time to build the tail, I decided to make a change. I was convinced that the normal cross tail would be to heavy. So I changed it to a V-tail. I set the opening angle between the two sides to 120 degrees and  extended their length by 15 percent to get enough area in the vertical projection. I hoped that nevertheless enough controllability was given. The maiden flight should show it.

The plans for the model included an extra sheet for the installation of spoilers. Unfortunately, the material for this was not included in the kit. As I wanted to use two separate servos for the two wing sides, I had to think about a different way how to control the spoilers. Now they are hinged at the front edge with plastic tape and pushed up directly by the servo horns. Small magnets hold them down in the retracted position.

The wing and the tail feathers were covered with transparent OraLight. White on the top and red and blue on the bottom. The fuselage was just painted with clear lacquer. Despite of the lighter tail, a lot of ballast was still needed in the nose of the model to get the right center of gravity. I decided to use a 2-cell LiPo of 2000 mAh combined with a UBEC-device. Now, the total flight weight came out at 630 g (~22 oz). So, this model seems to be more suitable for stronger winds.

For the high start a special rubber is required, which is extended with a fishing line. For this I made a wooden drum from a kit which was provided by Modellbau Claus Thiele.