In slope soaring the pilot needs a slope. Wind pushes against the slope and forms a vertical wind current off the lip of the slope. You use this current to stay aloft. The current will come at an angle and it is at that angle at which you will get the best lift. For slope soaring you need a slope or tall hill and winds of at least 6 mph. Slope soarers are often heavier than thermal birds and usually have ailerons. Thy are much faster and can do many more maneuvers than thermal models. You can hand launch off a slope or use a winch. Read my post Slopes in Peru (In Response to Evan-RCU) and you can see some slopes and sloper models.