This is the Apex. It was a .25-size glow-powered pure delta sport model that was published as a construction article in Radio Control Modeler in the mid-1980s.

In the article, the author says this was the second Apex he built. The first used a simple built-up plate wing that did not incorporate the drooped leading edge. He said that because of the drag, the model slowed down in the turns. He also said that the drooped leading edge eliminated this undesirable characteristic.

I used his wing design in my original F-106 model. I modified it by rounding the top of the drooped leading edge to soften the appearance and so that the trailing edge of the wing tips would have the 'curl' that is a defining characteristic of the F-106.

Here's a peek at his original plans.