With no air pressure on the tilted air track and an appropriate counterweight, the glider will be held in place by friction. Start the blower and, if the counterweight is sufficient, the glider will move up the incline.
The pulley end of the air track is raised on one of the large wooden blocks. Using a small glider, as photographed, a 10-gram weight is insufficient to pull the glider up the track with the air on, and the glider moves down the incline. Adding the 20-gram weight (total of 30 grams) causes the glider to move up the air track with the air on.