Then you might have something else in mind. Buzzard bait and BMatthews both explained what many consider it to be. They'd both qualify as "ANY" for sure.

I guess it depends on what most guys at the field would see a model do and say, "look at that sucker penetrate". In every case I can remember something like those words, they were marveling at a model that was flying back upwind better than other models had that day.

When it was a glider, it was one that was what you'd call a fast one, and usually carrying ballast. Gliders get their speed from energy that comes from their weight. They turn their potential energy into forward motion. More forward from more energy from more weight.

Nowadays I don't get to fly gliders but have heard comments about penetration. They were usually mumbled by guys who were sitting out the breeze because they had basically slow airplanes that had little chance to hurry back against the wind due to their lack of speed and abundance of drag.

Two things especially benefit "penetration", lower drag and higher speed. Of course, you usually see both in a single model. But with a glider, you can give it more potential for the higher speed deal.

Perhaps you'd describe again what you'd point out as penetration if you observed it?