All about RC soaring!

Model Airplane News, Dec 2003 by Garwood, Dave

The lighter the model, the weaker the lift it needs to sustain flight. It's a rare day when there's too much wind because when the wind increases, we fly smaller, heavier and faster models. If you can stand up in it, you can fly in it. The best way to determine whether there's enough lift to fly is to watch other sailplanes; second best is to watch gulls or hawks soaring at the slope. If no other fliers, human or bird, are working the slope, test the lift by firmly holding the model out in front of the slope in the lift. If it wants to rise out of your hand, there's probably enough lift to fly.

When you're ready to launch, step confidently to the overlook, and give the model a firm toss in a slightly downward direction-yes, downward, because at this point, you'll need airspeed more than altitude. The model may balloon upward suddenly, so be prepared to quickly push the elevator stick forward to prevent it from stalling. If the lift is sufficient, the model will soon be back above the hill, but if you don't have enough airspeed for solid control, it will crash. After a few seconds to build up speed, turn 90 degrees so that the plane is flying parallel to the slope. It will continue to gain altitude and will be flying above and out in front of the hill. Before it gets too small to see, make a 180-degree turn away from the hill and pass in front of the launch position. At the other end of the circuit, make another 180-degree turn, again turning away from the hill. You're now flying a basic slope-soaring pattern. Seen from above, it's a figure-8, always turning into the wind. We turn into the wind to keep the airspeed up and the ground speed down in the turns and to avoid being blown back over the hill, which is just about the worst thing that can happen because behind the hill, lift decreases rapidly and turbulence increases sharply.

Once you've launched and established a flight pattern, you may want to explore the limits of the lift zone. Generally, lift is strongest just above and slightly out in front of the overlook. Lift tapers off as the plane goes higher and decreases as it goes farther out. Usable lift can range from a few feet up to three times the height of the hill and from the overlook to 200 feet or more out in front. Finding the limit of the lift zone out in front of the hill is not difficult because it tapers off gradually. Just fly out until your model gently begins to settle, and then bring it back into stronger lift to keep it aloft. Flying behind the hill is hazardous, so take pains to stay out in front. We gain altitude by flying in the strongest part of the lift. In strong lift, you can get up to twice the height of the hill in two or three passes. In weaker lift, it may take many passes, gaining a few feet with each one, to get to a happy cruising altitude. We reduce altitude mainly by intentionally flying into areas of weaker lift.

ADVANCED TECHNIQUES

What do you do once you've got the basics? Aerobatics! Almost anything that can be done with a powered model can be done with a slope model. Those with long-wing thermal-glider experience may try loops first. Former powered-model pilots may prefer rolls as their first departure from straight and level. For either maneuver, gain some altitude, enter a shallow dive to build up speed, and then perform the maneuver. Inverted passes are cool, and flying the whole figure-8 pattern inverted is super-cool. Immelmann turns, split-S's and Cuban-8s are well within the performance envelope of fast aileron and elevator slope ships.